Amrix is a brand-name prescription medication. It’s FDA-approved for use with rest and physical therapy to relieve certain muscle spasms in adults. Muscle spasms are sudden, involuntary muscle movements.

Specifically, Amrix treats muscle spasms caused by acute (short-term), painful musculoskeletal conditions, such as a muscle strain or injury. And Amrix should only be taken for up to 2 to 3 weeks.

Note: Amrix isn’t effective for relieving muscle spasms caused by brain or spinal cord disease, such as cerebral palsy. See the “Amrix uses” section below for more information about how Amrix is used.

Drug details

Amrix works to relieve muscle pain, tenderness, and stiffness. It belongs to a class of drugs called muscle relaxants. A drug class is a group of medications that act in a similar way.

Amrix comes as extended-release (ER) capsules that you take by mouth once a day. (ER drugs slowly release their active drug into your body over time.) Amrix is available in strengths of 15 milligrams (mg) and 30 mg.

Effectiveness

For information about the effectiveness of Amrix, see the “Amrix uses” section below.

Amrix is a brand-name drug that contains the active drug cyclobenzaprine. This active drug is also available as a generic medication. A generic drug is an exact copy of the active drug in a brand-name medication.

The generic is considered to be as safe and effective as the original drug. Generics tend to cost less than brand-name drugs.

If you’re interested in using the generic form of Amrix, talk with your doctor. They can tell you if it comes in forms and strengths that can be used for your condition.

The Amrix dosage your doctor prescribes will depend on the severity of the condition you’re using Amrix to treat.

Typically, your doctor will start you on a low dosage. If this doesn’t work for you, they may increase your dosage. Your doctor will ultimately prescribe the smallest dosage that provides the desired effect.

The following information describes dosages that are commonly used or recommended. But be sure to take the dosage your doctor prescribes for you. They’ll determine the best dosage to fit your needs.

Drug forms and strengths

Amrix comes as extended-release (ER) capsules that you take by mouth. ER drugs slowly release their active drug into your body over time.

Amrix is available in strengths of 15 milligrams (mg) and 30 mg.

Dosage for muscle relaxant therapy

The usual Amrix dosage for adults is 15 mg, once a day. If this dosage doesn’t work well enough for you, your doctor may increase it to 30 mg, once a day.

Amrix should be taken at the same time each day. And it shouldn’t be taken for longer than 2 to 3 weeks.

What if I miss a dose?

If you miss a dose of Amrix, take it as soon as you remember, unless there are only a few hours until your next dose is scheduled. In this case, skip the missed dose and take your next dose as scheduled.

Don’t take two doses together to make up for a missed dose of Amrix. Doing this can increase your risk for serious side effects.

To help make sure that you don’t miss a dose, try using a medication reminder. This can include setting an alarm on your phone or downloading a reminder app. A kitchen timer can also work.

Will I need to use this drug long term?

No, Amrix isn’t meant to be used as a long-term treatment. It should only be taken for up to 2 to 3 weeks. It’s not known if Amrix is safe or effective for long-term use.

Amrix can cause mild or serious side effects. The following lists contain some of the key side effects that may occur while taking Amrix. These lists do not include all possible side effects.

For more information about the possible side effects of Amrix, talk with your doctor or pharmacist. They can give you tips on how to deal with any side effects that may be bothersome.

Note: The Food and Drug Administration (FDA) tracks side effects of drugs it has approved. If you’d like to notify the FDA about a side effect you’ve had with Amrix, you can do so through MedWatch.

Mild side effects

Mild side effects* of Amrix can include:

Most of these side effects may go away within a few days or a couple of weeks. But if they become more severe or don’t go away, talk with your doctor or pharmacist.

* This is a partial list of mild side effects from Amrix. To learn about other mild side effects, talk with your doctor or pharmacist or visit Amrix’s prescribing information.
† For more information about this side effect, see “Side effect details” below.

Serious side effects

Serious side effects from Amrix aren’t common, but they can occur. Call your doctor right away if you have serious side effects. Call 911 or your local emergency number if your symptoms feel life threatening or you think you’re having a medical emergency.

Serious side effects and their symptoms can include:

  • Serotonin syndrome (a dangerous condition caused by a buildup of the chemical serotonin in your body). Symptoms can include:
    • fast heartbeat
    • sweating
    • tremor (uncontrolled shaking) or twitching
    • stiff muscles
    • loss of coordination
    • confusion
    • hallucinations (seeing or hearing something that’s not really there)
  • Heart problems (such as a fast or irregular heartbeat) that could lead to a heart attack or stroke. Symptoms can include:
    • chest pain when exercising
    • dizziness
    • fainting without a clear cause
    • feeling that your heart is pounding, racing, or skipping a beat
    • severe pain, pressure, or tightness in your chest, arm, throat, neck, or jaw
    • shortness of breath
    • nausea or vomiting
    • cold sweats
    • drooping on one side of your face
    • sudden weakness or numbness in one arm
    • slurred speech or trouble speaking
  • Allergic reaction.*

* For more information about these side effects, see “Side effect details” below.

Side effect details

You may wonder how often certain side effects occur with this drug. Here’s some detail about certain side effects this drug may cause.

Allergic reaction

As with most drugs, some people can have an allergic reaction after taking Amrix. It’s not known how often this may have occurred in clinical studies of Amrix.

Symptoms of a mild allergic reaction can include:

  • rash
  • itchiness
  • flushing (warmth, swelling, or redness in your skin)

A more severe allergic reaction is rare but possible. Symptoms of a severe allergic reaction can include:

  • swelling under your skin, typically in your eyelids, lips, hands, or feet
  • swelling of your tongue, mouth, or throat
  • trouble breathing

Call your doctor right away if you have an allergic reaction to Amrix, as the reaction could become severe. Call 911 or your local emergency number if your symptoms feel life threatening or you think you’re having a medical emergency.

Sleepiness

Amrix may cause sleepiness. In clinical studies, sleepiness occurred in 1% to 2% of people who took Amrix, depending on their dosage of the drug. In comparison, sleepiness wasn’t reported in people who took a placebo (a treatment with no active drug).

You shouldn’t drive or operate machinery until you know how Amrix affects you. And if taking Amrix makes you feel sleepy, don’t drive or operate machines. If you have questions about this, talk with your doctor.

Dizziness

Dizziness is one of the most common side effects of Amrix. In clinical studies, dizziness occurred in 3% to 6% of people who took Amrix, depending on their dosage of the drug. In comparison, dizziness occurred in 2% of people who took a placebo (a treatment with no active drug).

If you feel dizzy while taking Amrix, lying down might help reduce this side effect. Also, you should avoid driving or operating machinery if taking Amrix makes you feel dizzy.

Rarely, dizziness can be a symptom of a heart problem. Heart problems are a possible serious side effect of Amrix. (See “Serious side effects” above for details.) If you feel dizzy and experience any of the following symptoms, contact your doctor right away:

  • chest pain
  • a change in your heartbeat
  • fainting

Dry mouth

Dry mouth is the most common side effect of Amrix reported in clinical studies. Specifically, 6% to 14% of people who took Amrix had a dry mouth, depending on dosage. In comparison, 2% of people who took a placebo (a treatment with no active drug) had a dry mouth.

Note: If you have a dry mouth with Amrix, sipping water may help relieve this. Also, if you take medications that dissolve in your mouth, the medications may not dissolve as well if you have a dry mouth. This can make these medications less effective. So, if you need to take this form of medication, you should rinse your mouth with water first.

If you have dry mouth that’s bothersome or causes problems with taking other medications, talk with your doctor.

Digestive problems

Amrix can cause various digestive side effects. The most common ones include constipation, nausea, and indigestion.

In clinical studies:

  • Constipation occurred in 1% to 3% of people who took Amrix, depending on dosage. This side effect wasn’t reported in people who took a placebo (a treatment with no active drug).
  • Nausea occurred in 3% of people who took Amrix, compared with 1% of people who took a placebo.
  • Indigestion occurred in 0% to 4% of people who took Amrix, depending on dosage. In comparison, indigestion occurred in 1% of people who took a placebo.

If you have nausea or indigestion while taking Amrix, taking the medication with food may help. And if you have constipation with Amrix, this may be helped by drinking plenty of water. Eating high fiber foods (such as fruits, vegetables, and whole grains) can also help relieve constipation.

If you have digestive side effects that are bothersome, talk with your doctor or pharmacist. They can suggest ways to help reduce these side effects.

Blurry vision

It’s possible to have blurry vision while taking Amrix.

Blurry vision didn’t occur in clinical studies of Amrix. But this side effect has been reported in people taking immediate-release (IR) forms of cyclobenzaprine. Cyclobenzaprine is the active drug in Amrix.*

In one study, blurry vision was reported in 1% to 3% of people taking IR cyclobenzaprine.

If you have blurry vision with Amrix, you should avoid driving or operating machinery. If you have questions about this, or if you have blurry vision that’s bothersome or severe, talk with your doctor.

* Amrix contains an extended-release form of cyclobenzaprine. This means that Amrix slowly releases its active drug into your body over time. But IR drugs release their active drug into your body all at once.

Other drugs are available that can be used to treat muscle spasms caused by acute (short-term) musculoskeletal conditions.* Some of these drugs may be a better fit for you than others. If you’re interested in finding an alternative to Amrix, talk with your doctor. They can tell you about other medications that may work well for you.

Examples of other drugs that may be used as muscle relaxants for certain muscle spasms include:

* Muscle spasms are sudden, involuntary muscle movements. See the “Amrix uses” section below for more information about how Amrix is used.

You may wonder how Amrix compares with other medications that are prescribed for similar uses. Here, we look at how Amrix and Flexeril are alike and different.

Ingredients, forms, and administration

Amrix and Flexeril are both brand-name medications that contain the active drug cyclobenzaprine. Flexeril has been discontinued and is no longer available.

But generic forms of Flexeril are still available. A generic form of Amrix is also available. A generic drug is an exact copy of the active drug in a brand-name medication.*

Amrix is a long-acting form of cyclobenzaprine. Amrix and its generic form come as extended-release (ER) capsules that are taken by mouth once a day. ER drugs such as Amrix release their active drug into your body slowly over time.

Flexeril was a short-acting form of cyclobenzaprine that was typically taken three times a day. Flexeril and its generic forms are immediate-release (IR) tablets that are typically taken three times a day. IR drugs release their active drug into your body all at once.

* Generic drugs are prescribed for the same uses as the original drug. And they’re considered to be as safe and effective as the original drug.

Uses

The Food and Drug Administration (FDA) has approved Amrix, Flexeril, and the generic forms of Flexeril to treat certain muscle spasms in adults. Muscle spasms are sudden, involuntary muscle movements. All of these drugs are muscle relaxants, which help relax the muscles without affecting your ability to control and use them.

Specifically, these drugs are approved to treat muscle spasms caused by acute (short-term), painful musculoskeletal conditions. These conditions include muscle strains or injuries.

For this use, Amrix and Flexeril are prescribed along with rest and physical therapy. And it’s important to note that these drugs should only be used for 2 to 3 weeks. They’re not effective for relieving muscle spasms caused by brain or spinal cord disease, such as cerebral palsy.

Side effects and risks

Amrix, Flexeril, and generic cyclobenzaprine all contain the same active drug. So, these medications can cause very similar side effects. Below are examples of these side effects.

Mild side effects

This list contains up to 10 of the most common mild side effects that can occur with Amrix, Flexeril, and generic cyclobenzaprine:

Serious side effects

This list contains examples of serious side effects that can occur with Amrix, Flexeril, and generic cyclobenzaprine:

Effectiveness

A clinical study has compared the effectiveness of Amrix with that of IR cyclobenzaprine. This study found that these drugs were similarly effective as muscle relaxants.

Specifically, both drugs relieved pain and helped improve movement of people’s affected body area within about 5 days. Amrix also caused less sleepiness than IR cyclobenzaprine.

If you have questions about the effectiveness of these drugs, talk with your doctor about which treatment is right for you.

Costs

According to estimates on GoodRx.com, Amrix costs much more than the generic form of Flexeril, cyclobenzaprine. (Brand-name Flexeril is no longer available). The actual price you’ll pay for either drug depends on your insurance plan, your location, and the pharmacy you use.

You may wonder how Amrix compares with other medications that are prescribed for similar uses. Here, we look at how Amrix and Soma are alike and different.

Ingredients

Amrix contains the active drug cyclobenzaprine. Soma contains carisoprodol.

Both Amrix and Soma are muscle relaxants. Muscle relaxants help relax the muscles without affecting your ability to control and use them.

Uses

The Food and Drug Administration (FDA) has approved both Amrix and Soma to treat certain muscle spasms in adults. Muscle spasms are sudden, involuntary muscle movements.

Specifically, these drugs are approved to treat muscle spasms caused by acute (short-term), painful musculoskeletal conditions. These conditions include muscle strains or injuries.

For this use, Amrix and Soma are prescribed along with rest and physical therapy. And it’s important to note that these drugs should only be used for 2 to 3 weeks. They’re not effective for relieving muscle spasms caused by brain or spinal cord disease, such as cerebral palsy.

Drug forms and administration

Amrix comes as extended-release (ER) capsules that are taken by mouth once a day. ER drugs release their active drug into your body slowly over time.

Soma comes as immediate-release (IR) tablets that are taken by mouth three times a day, and when you go to bed. IR drugs release their active drug into your body all at once.

Side effects and risks

Amrix and Soma both contain a muscle relaxant drug. For this reason, these medications can cause very similar side effects, but some different ones as well. Below are examples of these side effects.

Mild side effects

These lists contain up to 10 of the most common mild side effects that can occur with either Amrix or Soma, as well as mild side effects that both drugs may share.

Serious side effects

These lists contain examples of serious side effects that can occur with either Amrix or Soma, as well as serious side effects that both drugs may share.

* With dependence, your body needs a drug in order for you to feel normal. Dependence can lead to misuse, which refers to using a drug for non-medical reasons or in a way that’s not approved.

Effectiveness

Amrix and Soma haven’t been directly compared in clinical studies. But studies have found both Amrix and Soma to be effective as muscle relaxants.

If you have questions about which drug is best for you, talk with your doctor.

Costs

According to estimates on GoodRx.com, Amrix costs more than Soma. The actual price you’ll pay for either drug depends on your insurance plan, your location, and the pharmacy you use.

Amrix and Soma are both brand-name drugs. They’re both available in generic form. Brand-name medications usually cost more than generics.

The Food and Drug Administration (FDA) approves prescription drugs such as Amrix to treat certain conditions. Amrix may also be used off-label for other conditions. Off-label drug use means using a drug for a purpose other than what it’s been approved for by the FDA.

Amrix for muscle relaxant therapy

Amrix is approved to treat certain muscle spasms in adults. Muscle spasms are sudden, involuntary muscle movements.

Specifically, Amrix is approved to treat muscle spasms caused by acute (short-term), painful musculoskeletal conditions. Acute musculoskeletal conditions affect the muscles and skeleton. They develop suddenly and last for a short period of time, typically a few days or weeks. They’re usually caused by an injury, such as a muscle strain.

Symptoms of a musculoskeletal injury may include:

  • muscle pain or tenderness
  • muscle spasms
  • muscle stiffness
  • trouble moving the affected area

Amrix is a muscle relaxant. It works to reduce muscle spasms and symptoms of musculoskeletal conditions. It’s commonly prescribed for acute back pain.

For this use, Amrix is prescribed with rest and physical therapy. And it’s important to note that Amrix should only be used for 2 to 3 weeks. It isn’t effective for relieving muscle spasms caused by brain or spinal cord disease, such as cerebral palsy.

Effectiveness for muscle relaxant therapy

Amrix was effective for treating muscle spasms caused by acute painful musculoskeletal conditions in two clinical studies. In these studies, adults took either Amrix or a placebo for 2 weeks. (A placebo is a treatment with no active drug.)

People in these studies rated the helpfulness of their treatment after 4 days and after 14 days. The percentage of people who rated the helpfulness of their treatment as excellent, very good, good, or fair is shown below:

Helpfulness of treatment was rated as:In people who took Amrix, after 4 days:In people who took a placebo, after 4 days:In people who took Amrix, after 14 days:In people who took a placebo, after 14 days:
Excellent3% to 5%2%21% to 23%16% to 19%
Very good19% to 20%8% to 16%30% to 33%14% to 19%
Good33% to 34%22% to 23%14% to 23%16% to 20%
Fair27% to 31%25% to 38%16%22% to 25%

People who took Amrix were more likely to have relief from pain and an improved ability to move their affected body area, compared with people who took a placebo.

People in these studies also rated the effect of treatment on their ability to carry out daily activities and their quality of sleep. For these factors, there were no significant differences in people’s ratings between the two groups.

Off-label use for Amrix

In addition to the use listed above, Amrix may also be used off-label for other conditions. Off-label drug use is when an FDA-approved drug is used for a purpose other than what it’s approved for. Below is an example of off-label use for Amrix.

Amrix for fibromyalgia

Amrix is not FDA-approved to treat fibromyalgia, but it might be prescribed off-label for this condition.

Fibromyalgia is a chronic (long-term) condition that causes widespread soft tissue pain and stiffness. Other symptoms can include sleep problems, such as irregular sleep patterns and feeling unrefreshed after sleep. Many people also have fatigue (lack of energy), problems with memory and concentration, anxiety, or depression.

The American College of Rheumatology recommends cyclobenzaprine (the active drug in Amrix) as an option for treating fibromyalgia. Specifically, cyclobenzaprine may help improve sleep in people with fibromyalgia. But recent research has found that cyclobenzaprine doesn’t seem to help with pain caused by fibromyalgia.

If you’re interested in taking Amrix for fibromyalgia, talk with your doctor. They can determine whether or not this treatment would be appropriate for you.

Amrix and children

Amrix isn’t approved for use in children. It’s not known if this brand-name form of cyclobenzaprine is safe or effective for treating children.

Some generic forms of cyclobenzaprine that are low-dose and immediate-release (IR)* are approved for children ages 15 years and older. (A generic drug is an exact copy of the active drug in a brand-name medication.)

* Amrix contains an extended-release form of cyclobenzaprine. This means that Amrix slowly releases its active drug into your body over time. But IR drugs release their active drug into the body all at once.

Amrix is approved to treat certain muscle spasms (sudden, involuntary muscle movements).* For this use, Amrix is prescribed with physical therapy and rest. These other treatments may also help reduce muscle spasms and associated symptoms.

Your doctor may also prescribe over-the-counter pain-relieving medications to take with Amrix. Examples of these medications include:

* Specifically, Amrix is approved to treat muscle spasms caused by acute (short-term) musculoskeletal conditions, such as a muscle strain or injury. See the “Amrix uses” section just above for more information about how Amrix is used.

Amrix and alcohol are both central nervous system (CNS) depressants. This means that they slow down the activity in your CNS. For this reason, drinking alcohol with Amrix can increase your risk for CNS depression.

CNS depression is when the body’s neurological functions slow down. This can cause effects such as sleepiness, dizziness, slurred speech, lack of coordination, and confusion. In serious cases, CNS depression may lead to slow, shallow breathing, loss of consciousness, coma, or even death.

Due to the risk of CNS depression, you should avoid drinking alcohol while you’re taking Amrix. If you have questions about the safety of drinking alcohol with Amrix, talk with your doctor.

Amrix can interact with several other medications. It can also interact with certain herbs and supplements.

Different interactions can cause different effects. For instance, some interactions can interfere with how well a drug works, while others can increase side effects or make them more severe.

Amrix and other medications

Below are lists of medications that can interact with Amrix. These lists do not contain all the drugs that may interact with Amrix.

Before taking Amrix, talk with your doctor and pharmacist. Tell them about all prescription, over-the-counter, and other drugs you take. Also, tell them about any vitamins, herbs, and supplements you use. Sharing this information can help you avoid potential interactions.

If you have questions about drug interactions that may affect you, ask your doctor or pharmacist.

Amrix and Vicodin

Vicodin is a brand-name pain-relieving medication that contains a combination of acetaminophen and hydrocodone. Vicodin has been discontinued and is no longer available. But generic versions of Vicodin are still available. (A generic drug is an exact copy of the active drug[s] in a brand-name medication.)

You shouldn’t take Amrix with Vicodin or generic versions of Vicodin. All of these drugs are central nervous system (CNS) depressants. This means that they slow down the activity in your CNS. Taking Amrix with Vicodin can increase your risk for CNS depression.

CNS depression is when the body’s neurological functions slow down. This can cause effects such as sleepiness, dizziness, slurred speech, lack of coordination, and confusion. In serious cases, CNS depression may lead to slow, shallow breathing, loss of consciousness, coma, or even death.

If you have questions about taking Amrix with Vicodin or generic forms of Vicodin, talk with your doctor.

Amrix and tramadol

Tramadol (Conzip, Ultram) is a type of pain-relieving medication called an opioid.

Amrix and tramadol are both CNS depressants. This means that they slow down the activity in your CNS. Taking Amrix with tramadol increases your risk for:

  • CNS depression. CNS depression is when the body’s neurological functions slow down. This can cause effects such as sleepiness, dizziness, slurred speech, lack of coordination, and confusion. In serious cases, CNS depression may lead to slow, shallow breathing, loss of consciousness, coma, or even death.
  • Serotonin syndrome. This is a dangerous side effect caused by a buildup of the chemical serotonin in your body. This can develop because both Amrix and tramadol can increase serotonin levels.*
  • Seizures (changes in the electrical activity of your brain).

Due to these risks, Amrix shouldn’t be taken with tramadol. If you have questions about this, talk with your doctor.

* See the “Amrix side effects” section above for more information about serotonin syndrome.

Amrix and MAOIs

Amrix shouldn’t be taken with drugs called monoamine oxidase inhibitors (MAOIs). MAOIs are a type of antidepressant drug. Antidepressants are used to treat depression.

Taking Amrix with MAOIs can cause serious side effects. These include seizures (changes in the electrical activity of your brain) and serotonin syndrome. Serotonin syndrome is a dangerous side effect caused by a buildup of the chemical serotonin in your body.*

Examples of MAOIs that you shouldn’t take Amrix with include:

  • linezolid (Zyvox), an antibiotic
  • methylene blue (Provayblue), which is used to treat certain blood disorders
  • phenelzine (Nardil)
  • isocarboxazid (Marplan)
  • tranylcypromine (Parnate)
  • selegiline (Emsam, Zelapar)
  • certain drugs used to treat Parkinson’s disease, such as rasagiline (Azilect)

You shouldn’t take Amrix if you’ve taken an MAOI during the last 14 days. If you currently take or have recently taken any of the drugs listed above, talk with your doctor about other treatment options.

* See the “Amrix side effects” section above for more information about serotonin syndrome.

Amrix and drugs that increase serotonin

Taking Amrix with drugs that increase levels of the chemical serotonin in your body can increase your risk for serotonin syndrome. Serotonin syndrome is a dangerous condition caused by a buildup of serotonin in your body. (See the “Amrix side effects” section above for more information about this.)

Examples of drugs that raise the risk of serotonin syndrome if taken with Amrix include:

If you take any of these drugs, talk with your doctor before taking Amrix. They may prescribe a lower-than-usual dosage of Amrix for you. Or they may recommend other treatment options.

Amrix and CNS depressants

CNS depressants are drugs that slow down the activity in your CNS. Amrix is a type of CNS depressant.

CNS depressants typically make you feel drowsy and less alert. Taking Amrix with another CNS depressant increases your risk for CNS depression.

CNS depression is when the body’s neurological functions slow down. This can cause effects such as sleepiness, dizziness, slurred speech, lack of coordination, and confusion. In serious cases, CNS depression may lead to slow, shallow breathing, loss of consciousness, coma, or even death.

You shouldn’t take Amrix with other CNS depressants. Examples of CNS depressant drugs include:

If you take any of these drugs, talk with your doctor about other treatment options.

Note: Alcohol is also a CNS depressant, and alcohol use with Amrix should be avoided. See the “Amrix and alcohol” section below for more information.

* Barbiturates and benzodiazepines are types of drugs that may be used to treat seizures, anxiety, sleeping problems, and other conditions.

Amrix and anticholinergic drugs

Anticholinergic drugs are a group of medications that have several different uses. For example, anticholinergic drugs may be used to treat chronic obstructive pulmonary disease (COPD), asthma, overactive bladder, and involuntary body movements.

Taking Amrix with an anticholinergic drug may increase your risk for certain side effects of Amrix. These may include constipation, dry mouth, blurred vision, and trouble urinating.

Examples of anticholinergic drugs include:

If you take any of these drugs, talk with your doctor before taking Amrix. They may prescribe a lower-than-usual dosage of Amrix for you. Or they may recommend other treatment options.

Amrix and herbs and supplements

Some herbs and supplements may interact with Amrix. These are described below. Make sure to check with your doctor or pharmacist before using any herbs and supplements while taking Amrix.

Amrix and St John’s wort

Taking Amrix with the herb St. John’s wort can increase your risk for a serious side effect called serotonin syndrome. Serotonin syndrome can occur if levels of the chemical serotonin get too high in your body.* And both Amrix and St. John’s wort can increase your serotonin levels.

If you take St. John’s wort, talk with your doctor before taking Amrix. They may prescribe a lower-than-usual dosage of Amrix for you. Or they may recommend other treatment options.

* See the “Amrix side effects” section above for more information about serotonin syndrome.

Amrix and tryptophan

Taking Amrix with tryptophan supplements increases your risk for a serious side effect called serotonin syndrome. Serotonin syndrome can occur if levels of the chemical serotonin get too high in your body.* And both Amrix and tryptophan can increase your serotonin levels.

If you take tryptophan, talk with your doctor before taking Amrix. They may prescribe a lower-than-usual dosage of Amrix for you. Or they may recommend other treatment options.

* See the “Amrix side effects” section above for more information about serotonin syndrome.

Amrix and foods

There aren’t any foods that have been specifically reported to interact with Amrix. If you have any questions about eating certain foods with Amrix, talk with your doctor.

Here are answers to some frequently asked questions about Amrix.

Will Amrix make me feel ‘high’?

It’s possible. This depends on how you define feeling “high.” Typically, feeling “high” describes feelings of euphoria (pleasure or extreme happiness). When taken as prescribed, Amrix doesn’t cause euphoria.

But taking Amrix can make you feel calm, relaxed, and sleepy. And some people may describe these effects as feeling “high.”

Some people may misuse Amrix to produce feelings of relaxation and euphoria. Drug misuse refers to using a drug for non-medical reasons or in a way that’s not approved, typically to produce a “high” feeling. Drug misuse tends to involve using higher doses of a drug than those prescribed for medical uses.

Misusing Amrix can cause dangerous side effects, particularly if it’s used with alcohol or other drugs.

If you’re concerned about how Amrix might make you feel, talk with your doctor. You should also talk with your doctor if you’re concerned about possible misuse of Amrix.

Is Amrix commonly misused?

No. Amrix isn’t commonly misused, compared with certain other drugs, such as opioids. (Opioids are a type of pain-relieving drug that are classified as controlled substances.*) But Amrix is still sometimes misused. For more information, see the “Amrix withdrawal and dependence” section below.

Misusing Amrix can have dangerous side effects, particularly if it’s used with alcohol or other drugs. If you’re concerned about misuse of Amrix, talk with your doctor.

* Controlled substances are drugs that have a high potential for dependence and misuse. (With dependence, your body needs a drug in order for you to feel normal.) Because of these risks, there are additional rules for how controlled substances are prescribed and dispensed.

Can older people take Amrix?

No, Amrix isn’t usually recommended for older people. If you’re age 65 years or older, Amrix can build up in your body. This increases your risk for side effects from the drug. If you’re age 65 years or older, ask your doctor about which other medications may be better options for treating your condition.

Will I be able to drive while I’m taking Amrix?

Maybe. But you should see how the medication affects you first. Amrix can cause sleepiness, dizziness, and blurry vision. If you have these side effects with Amrix, you shouldn’t drive or operate machinery.

If you have questions about this, or if you have bothersome side effects while taking Amrix, talk with your doctor.

Can I use Amrix with other pain relievers?

Yes, Amrix can be used with certain other pain relievers, as long as your doctor approves. For example, Amrix can typically be taken with:

But Amrix shouldn’t be taken with stronger pain relievers, such as opioids. Examples of these drugs include:

Taking Amrix with opioids can increase your risk for side effects from these drugs. Specifically, taking these drugs together can increase your risk for central nervous system (CNS) depression. CNS depression is when the body’s neurological functions slow down. This can cause effects such as sleepiness, dizziness, slurred speech, lack of coordination, and confusion. In serious cases, CNS depression may lead to slow, shallow breathing, loss of consciousness, coma, or even death.

Also, taking Amrix with tramadol or fentanyl can lead to serotonin syndrome. This is a serious side effect caused by high levels of the chemical serotonin in your body.

Make sure to check with your doctor or pharmacist before taking Amrix with another pain reliever. They can make sure it’s safe for you to take these drugs together.

To learn more about taking Amrix with other drugs, see the “Amrix interactions” section above. And see the “Amrix side effects” section above for more information about serotonin syndrome.

As with all medications, the cost of Amrix can vary. To find current prices for Amrix in your area, check out GoodRx.com.

The cost you find on GoodRx.com is what you may pay without insurance. The actual price you’ll pay depends on your insurance plan, your location, and the pharmacy you use.

Before approving coverage for Amrix, your insurance company may require you to get prior authorization. This means that your doctor and insurance company will need to communicate about your prescription before the insurance company will cover the drug. The insurance company will review the prior authorization request and decide if the drug will be covered.

If you’re not sure if you’ll need to get prior authorization for Amrix, contact your insurance company.

Financial and insurance assistance

If you need financial support to pay for Amrix, help may be available.

Medicine Assistance Tool’s site offers lists of programs that may help lower the cost of Amrix. For more information and to find out if you’re eligible for support, visit their website.

Mail-order pharmacies

Amrix may be available through a mail-order pharmacy. Using this service may help lower the drug’s cost and allow you to get your medication without leaving home.

If you’re interested in this option, check with your doctor and insurance company. Some Medicare plans may help cover the cost of mail-order medications.

If you don’t have insurance, you can ask your doctor or pharmacist about online pharmacy options.

Generic version

Amrix is available in a generic form called cyclobenzaprine. A generic drug is an exact copy of the active drug in a brand-name medication. The generic is considered to be as safe and effective as the original drug. And generics tend to cost less than brand-name drugs. To find out how the cost of cyclobenzaprine compares with the cost of Amrix, visit GoodRx.com.

If your doctor has prescribed Amrix and you’re interested in using cyclobenzaprine instead, talk with your doctor. They may have a preference for one version or the other. You’ll also need to check your insurance plan, as it may only cover one or the other.

Amrix is used to relieve certain muscle spasms (sudden, involuntary muscle movements).

Specifically, Amrix is approved to treat muscle spasms caused by acute (short-term), painful musculoskeletal conditions. Acute musculoskeletal conditions affect the muscles and skeleton. They develop suddenly and last for a short period of time, typically a few days or weeks. They’re usually caused by an injury, such as a muscle strain.

Amrix is a muscle relaxant. Muscle relaxants help relax the muscles without affecting your ability to control and use them.

Amrix is used along with rest and physical therapy to help you recover from your musculoskeletal condition. These other treatments may also help reduce muscle spasms and associated symptoms.

What Amrix does

Amrix helps relax and ease muscle spasms. To do this, the drug works in an area at the base of your brain called the brainstem. Amrix reduces nerve signals that are sent to your muscles that cause them to spasm.

As your muscles relax, symptoms such as muscle pain, tenderness, and stiffness may be reduced. This muscle relaxation can also improve your ability to move the affected area.

How long does Amrix take to work?

Amrix begins working as soon as you take your dose. And the drug can be detected in your body about 1.5 hours after you take a dose.

In clinical studies, 71% of people taking Amrix reported that the medication was helpful 4 days after they began taking it. (For more information about how people in these studies responded to taking Amrix, see the “Amrix uses” section above).

How long does Amrix stay in your system?

Amrix stays in your system for about a week after you stop taking it.

It can take about 6 to 8 days for Amrix to fully leave your system. But this may vary depending on your age, weight, genetics, kidney function, or other medications you may be taking.

Specifically, Amrix has a half-life of about 32 hours. The half-life of a drug is the amount of time it takes for your body to remove half a dose of the drug from your system. It typically takes about five half-lives for a drug to be removed from your blood.

Using more than the recommended dosage of Amrix can lead to serious side effects. Although rare, death can occur with overdose of Amrix. Don’t use more Amrix than your doctor recommends.

Overdose symptoms

Symptoms of an overdose can include:

What to do in case of overdose

If you think you’ve taken too much of this drug, call your doctor. You can also call the American Association of Poison Control Centers at 800-222-1222 or use their online tool. But if your symptoms are severe, call 911 or your local emergency number, or go to the nearest emergency room right away.

You should take Amrix according to your doctor’s or healthcare provider’s instructions.

When to take

Amrix should be taken once a day. You can take your dose at any time of day. But make sure to take Amrix at the same time each day.

To help make sure that you don’t miss a dose, try using a medication reminder. This can include setting an alarm on your phone or downloading a reminder app. A kitchen timer can also work.

Taking Amrix with food

You can take Amrix either with or without food.

Note: If you need to split Amrix capsules and take the contents with food, only applesauce may be used for this purpose. See below for details.

Can Amrix be crushed, split, or chewed?

Amrix capsules should ideally be swallowed whole.

Don’t chew Amrix capsules. Doing this will stop the drug’s extended-release (ER) action from working.*

If you have trouble swallowing Amrix, you can split open the capsule and sprinkle the contents on a spoonful of applesauce. Swallow this right away, without chewing. Then, rinse a drink around your mouth and swallow it, to make sure you’ve swallowed all the medication. (Note: Other foods besides applesauce shouldn’t be used to help you take Amrix. Other foods haven’t been tested in clinical trials.)

* Amrix comes as ER capsules. This means that Amrix slowly releases its active drug, cyclobenzaprine, into your body over time. This gives Amrix a long-acting effect.

It’s not known if Amrix is safe to take during pregnancy. Amrix use during pregnancy hasn’t been studied.

Studies in animals found that when Amrix was given to pregnant females, their offspring were less likely to survive. Their offspring were also more likely to be born with a low body weight. But studies in animals don’t always predict what will happen in humans who take the drug.

There have been a few reports of Amrix use in pregnant women. These reports didn’t suggest that there was any harm caused by taking the drug during pregnancy. But further study is needed to determine whether or not Amrix is safe to take during pregnancy.

If you’re pregnant or planning a pregnancy, talk with your doctor about the possible risks and benefits of taking Amrix.

It’s not known if Amrix is safe to take during pregnancy. If you’re sexually active and you or your partner can become pregnant, talk with your doctor about your birth control needs while you’re using Amrix.

For more information about taking Amrix during pregnancy, see the “Amrix and pregnancy” section above.

It’s not known if Amrix passes into breast milk or can affect a child who’s breastfed. And it’s not known if Amrix affects the way your body makes breast milk.

If you’re breastfeeding or planning to breastfeed, talk with your doctor about the possible risks and benefits of taking Amrix.

Before taking Amrix, talk with your doctor about your health history. Amrix may not be right for you if you have certain medical conditions or other factors affecting your health. These include:

  • Hyperthyroidism (a condition in which you have an overactive thyroid gland). Amrix can cause a fast or irregular heartbeat. A fast heartbeat can also be a symptom of hyperthyroidism. Taking Amrix could make this symptom worse. And this could lead to serious side effects, such as a heart attack or stroke. If you have an overactive thyroid, you shouldn’t take Amrix. Ask your doctor about which other medications are better options for you.
  • Heart problems. Amrix can cause a fast or irregular heartbeat. For this reason, Amrix could worsen certain heart problems. And this could lead to serious side effects, such as a heart attack or stroke. If you have an irregular heartbeat, heart block, or heart failure or you’ve recently had a heart attack, you shouldn’t take Amrix. Ask your doctor about which other medications are better options for you.
  • Allergic reaction. If you’ve had an allergic reaction to Amrix or any of its ingredients, you shouldn’t take Amrix. Ask your doctor about which other medications are better options for you.
  • Older age. If you’re age 65 years or older, Amrix can build up in your body. This can increase your risk for side effects with this drug. Amrix isn’t usually recommended for people over 65 years old. Ask your doctor about which other medications are better options for you.
  • Liver problems. Amrix is broken down by your liver. If your liver doesn’t work well, Amrix can build up in your body. This can increase your risk for side effects from the drug. For this reason, Amrix isn’t usually recommended for people with liver problems. Ask your doctor about which other medications are better options for you.
  • Trouble passing urine. If you have trouble passing urine or emptying your bladder, taking Amrix could make this worse. Talk with your doctor about whether or not Amrix is right for you.
  • Increased pressure in your eye or glaucoma. If you have increased pressure in your eye or glaucoma (an eye condition commonly caused by increased eye pressure), taking Amrix could make this worse. Talk with your doctor about whether or not Amrix is right for you.
  • Pregnancy. It’s not known if Amrix is safe to take during pregnancy. For more information, see the “Amrix and pregnancy” section above.
  • Breastfeeding. It’s not known if Amrix passes into breast milk or affects breast milk production. For more information, see the “Amrix and breastfeeding” section above.

Note: For more information about the potential negative effects of Amrix, see the “Amrix side effects” section above.

There haven’t been studies into whether or not Amrix can cause drug dependence. With drug dependence, you need a drug to function normally. If you’re dependent on a drug, you may have withdrawal symptoms when you stop taking it.

Amrix has a similar chemical structure to tricyclic antidepressants (a type of drug used to treat depression). Tricyclic antidepressants can cause dependence. And it’s possible to have withdrawal symptoms if you’ve been taking a tricyclic antidepressant for a long period of time and you suddenly stop.

But taking Amrix as prescribed for 2 to 3 weeks isn’t known to cause drug dependence. Withdrawal symptoms haven’t been reported when stopping Amrix after taking it for this short amount of time.

However, if Amrix is used for longer than 2 or 3 weeks, withdrawal symptoms may occur when you stop taking the drug. These symptoms may include nausea, headache, or feeling generally unwell. Amrix may be used for longer periods of time if it’s used off-label to treat fibromyalgia (a condition that causes widespread soft tissue pain and stiffness). Misusing the drug may also lead to longer-term use.

If you’re concerned about withdrawal symptoms when stopping Amrix, talk with your doctor.

When you get Amrix from the pharmacy, the pharmacist will add an expiration date to the label on the bottle. This date is typically 1 year from the date they dispensed the medication.

The expiration date helps guarantee that the medication is effective during this time. The current stance of the Food and Drug Administration (FDA) is to avoid using expired medications. If you have unused medication that has gone past the expiration date, ask your pharmacist if you can still use it.

Storage

How long a medication remains good can depend on many factors, including how and where you store it.

Amrix capsules should be stored at a room temperature of 77°F (25°C). If needed, the capsules can be kept at a temperature of 59°F to 86°F (15°C to 30°C) for short periods of time.

Keep Amrix capsules in a tightly sealed container away from light. Avoid storing this medication in areas where it could get damp or wet, such as bathrooms.

Disposal

If you no longer need to take Amrix and have leftover medication, it’s important to dispose of it safely. This helps prevent others, including children and pets, from taking the drug by accident. It also helps keep the drug from harming the environment.

This article provides several useful tips on medication disposal. You can also ask your pharmacist for information about how to dispose of your medications.

Disclaimer: Medical News Today has made every effort to make certain that all information is factually correct, comprehensive, and up-to-date. However, this article should not be used as a substitute for the knowledge and expertise of a licensed healthcare professional. You should always consult your doctor or other healthcare professional before taking any medication. The drug information contained herein is subject to change and is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. The absence of warnings or other information for a given drug does not indicate that the drug or drug combination is safe, effective, or appropriate for all patients or all specific uses.