Clonazepam (Klonopin) is a generic prescription medication. As with other drugs, clonazepam can cause side effects. The drug is prescribed to treat the following in certain situations:

You may be prescribed clonazepam short term or long term. For panic disorder, your doctor may have you take clonazepam for a short time. It’s not known whether the drug is effective at treating panic disorder long term. For seizure disorders, long-term treatment may be recommended. Your doctor can advise you on the right treatment plan for you.

Clonazepam is available as an oral tablet and an orally disintegrating tablet.

Read on to learn about potential common, mild, and serious side effects. For a general overview of clonazepam, including details about its uses, refer to this article. Your doctor can also tell you more about clonazepam.

Clonazepam can cause certain side effects (also called adverse effects). Some of these are more common than others. The side effects may be temporary, lasting a few days to weeks. However, if the side effects last longer than that, bother you, or become severe, be sure to talk with your doctor or pharmacist.

These are just a few of the more common side effects reported by people who took clonazepam in clinical trials:

  • headache
  • increased salivation
  • sleepiness
  • muscle pain or weakness
  • sexual side effects, such as erectile dysfunction or changes in libido (sex drive)

Mild side effects can occur with clonazepam. This list does not include all possible mild side effects of the drug. For more information, you can refer to clonazepam’s prescribing information.

Mild side effects that have been reported with clonazepam include:

These side effects may be temporary, lasting a few days to weeks. However, if the side effects last longer than that, bother you, or become severe, be sure to talk with your doctor or pharmacist.

Note: After the Food and Drug Administration (FDA) approves a drug, it tracks and reviews side effects of the medication. If you develop a side effect while taking clonazepam and want to tell the FDA about it, visit MedWatch.

* For more information about this side effect, see “Clonazepam: Side effect specifics” below.

Clonazepam may cause serious side effects, but they are not very common.

The list below may not include all possible serious side effects of the drug. For more information, you can refer to clonazepam’s prescribing information.

If you develop serious side effects while taking clonazepam, call your doctor right away. If the side effects seem life threatening or you think you’re having a medical emergency, immediately call 911 or your local emergency number.

Serious side effects that have been reported and their symptoms include:

  • Mood changes. Symptoms can include:
    • feeling hopeless
    • anger or irritability
  • Suicidal thoughts or behaviors. Symptoms can include:
    • impulsiveness
    • agitation (feeling restless, aggravated, or annoyed)
  • Respiratory depression (slow, shallow breathing). Symptoms can include:
    • excessive tiredness
    • headache
    • confusion
    • fatigue
  • Seizure.* Symptoms can include:
    • loss of consciousness
    • staring
    • uncontrolled movement of your arms or legs
  • Memory loss.
  • Problems with muscle coordination or motor skills, such as unsteadiness and changes in grip strength.
  • Risk of dependence and withdrawal.†‡
  • Risks when taken with opioids.†‡
  • Low blood pressure.‡
  • Severe allergic reaction.‡

* If you’re taking clonazepam for seizures, see “Clonazepam: Precautions” below.
† Clonazepam oral tablets and orally disintegrating tablets have a boxed warning for this side effect. This is a serious warning from the Food and Drug Administration (FDA).
‡ To learn more, see “Clonazepam: Side effect specifics“ below.

Suicide prevention

If you know someone at immediate risk of self-harm, suicide, or hurting another person:

  • Ask the tough question: “Are you considering suicide?”
  • Listen to the person without judgment.
  • Call 911 or the local emergency number, or text TALK to 741741 to communicate with a trained crisis counselor.
  • Stay with the person until professional help arrives.
  • Try to remove any weapons, medications, or other potentially harmful objects.

If you or someone you know is having thoughts of suicide, a prevention hotline can help. The 988 Suicide and Crisis Lifeline is available 24 hours a day at 988. During a crisis, people who are hard of hearing can use their preferred relay service or dial 711 then 988.

Click here for more links and local resources.

Clonazepam is approved to treat certain seizure disorders in children. This drug is not approved for children with panic disorder.

In most cases, children taking clonazepam will have side effects similar to those in adults taking the drug.

However, children may have a higher risk of paradoxical reactions than adults. A paradoxical reaction occurs when a drug has the opposite effect than what’s usually reported. For example, one of the most common side effects of clonazepam is sleepiness. However, sometimes the drug can cause a child to be more energetic than usual.

If you have questions or concerns about side effects that your child may experience with clonazepam, talk with their doctor.

Learn more about some of the side effects that clonazepam may cause. To find out how often side effects occurred in clinical trials, see the prescribing information for clonazepam oral tablets and orally disintegrating tablets.

Risk of dependence and withdrawal

Clonazepam may cause dependence or withdrawal. In fact, the drug has a boxed warning for this risk. A boxed warning is the most serious warning from the Food and Drug Administration (FDA). The purpose of a boxed warning is to alert patients and doctors about the risks of taking a medication.

Dependence is when your body needs a medication to function as usual. It’s possible to develop dependence on a drug even if you take it exactly as your doctor prescribes.

If you stop taking a drug you’re dependent on, you may experience withdrawal symptoms. Withdrawal symptoms can start after you stop treatment with clonazepam. They can last for weeks or months after your treatment ends. Examples of withdrawal symptoms may include:

You may be at an increased risk of withdrawal and dependence if you take clonazepam for a long time or at a high dose.

What you can do

You should not stop taking clonazepam without first consulting your doctor. In most cases, they’ll slowly decrease your dose of clonazepam over time so that your body can adjust to the change. This should decrease your risk of developing withdrawal symptoms.

Your doctor can help answer other questions you may have about dependence or withdrawal symptoms with clonazepam.

Risks when taken with opioids

Clonazepam is a type of medication called a benzodiazepine. If you take clonazepam or any benzodiazepine with an opioid drug, you have an increased risk of serious side effects. In fact, clonazepam has a boxed warning for this risk. A boxed warning is the most serious warning from the FDA. The purpose of a boxed warning is to warn patients and prescribers about serious risks associated with a drug.

Both clonazepam and opioids can cause a condition called central nervous system (CNS) depression. This condition can cause difficulty breathing, sleepiness, and coma. These effects can, in rare cases, be fatal. If you take clonazepam and an opioid, your risk of CNS depression increases.

Examples of opioids include:

  • oxycodone (Roxicodone, OxyContin)
  • hydrocodone (Hysingla)
  • morphine (MS Contin)

What you can do

Opioids are typically prescribed to help ease pain. If you feel that you need a pain reliever while taking clonazepam, talk with your doctor. They may be able to recommend a treatment option other than an opioid drug.

If your doctor does prescribe clonazepam and an opioid medication, they’ll likely have you take the lowest dose of each drug for the shortest time possible. This should help reduce the risk of serious side effects.

Weight gain or weight loss

Weight gain and weight loss were reported in people taking clonazepam for seizure disorders, but this was not common. People taking clonazepam for panic disorder did not report weight changes.

What you can do

If you experience weight gain or weight loss during your treatment with clonazepam, talk with your doctor. They can help determine the cause. In addition, they may be able to recommend ways to manage your weight, such as with physical activity or diet.

Low blood pressure

Low blood pressure was reported rarely in people taking clonazepam for panic disorder. People taking the drug for seizure disorders did not report this side effect.

One particular type of low blood pressure that may occur is orthostatic hypotension. This condition happens when changing positions, such as standing up quickly.

Symptoms of low blood pressure may include:

  • dizziness
  • blurry vision
  • weakness
  • confusion
  • fainting

What you can do

If you develop symptoms of low blood pressure while taking clonazepam, tell your doctor. They can check your blood pressure to see whether it’s low. If the drug is the cause, your doctor may lower your dose.

Constipation

Constipation was reported as a rare side effect in people taking clonazepam for either panic disorder or seizure disorders.

Symptoms of constipation can include:

  • stool that’s hard, lumpy, or dry
  • trouble passing stool
  • nausea
  • bloating
  • abdominal pain

What you can do

If you experience constipation during your treatment with clonazepam, tell your doctor or pharmacist. They may be able to recommend ways to ease this side effect. For example, they may suggest an over-the-counter treatment for constipation, such as polyethylene glycol (MiraLAX).

Allergic reaction

As with most drugs, clonazepam can cause an allergic reaction in some people.

Symptoms can be mild or serious and can include:

  • skin rash
  • itching
  • flushing
  • swelling under your skin, typically in your eyelids, lips, hands, or feet
  • swelling of your mouth, tongue, or throat, which can make it hard to breathe

What you can do

For mild symptoms of an allergic reaction, call your doctor right away. They may recommend ways to ease your symptoms and determine whether you should keep taking clonazepam. However, if your symptoms are serious and you think you’re having a medical emergency, immediately call 911 or your local emergency number.

Most side effects of clonazepam are short term. They should improve or go away throughout your treatment or after stopping treatment. It’s possible to develop long-term side effects with clonazepam as well, but these are not common.

Examples of long-term side effects that may occur with clonazepam can include:

  • mood changes
  • suicidal thoughts or behaviors
  • seizure
  • memory loss
  • problems with muscle coordination or motor skills, such as unsteadiness and changes in grip strength
  • risk of dependence and withdrawal*†
  • weight gain or weight loss†

If you have concerns about how long-term side effects from clonazepam may affect you, talk with your doctor or pharmacist.

† Clonazepam oral tablets and orally disintegrating tablets have a boxed warning for this side effect. This is a serious warning from the Food and Drug Administration (FDA).
‡ To learn more, see “Clonazepam: Side effect specifics” above.

Clonazepam may cause several side effects. Here are some frequently asked questions about the drug’s side effects and their answers.

Do the 0.5-mg and 1-mg strengths of clonazepam have different side effects than other strengths?

Possibly. Your risk of side effects from clonazepam may increase if you take a higher dose of the medication. Clonazepam oral tablets are available in strengths of 0.5 milligrams (mg), 1 mg, and 2 mg. Clonazepam disintegrating tablets are available in strengths of 0.125 mg, 0.25 mg, 0.5 mg, 1 mg, and 2 mg.

Taking a higher dose of a drug means that more medication is present in your body. This can increase your risk of side effects. For example, if you take a 2-mg dose of clonazepam, you may have a higher risk of side effects than if you take a 0.5-mg or 1-mg dose. Keep in mind that you should not adjust your dose of clonazepam on your own. Your doctor will prescribe the right dose for you.

If you have concerns about side effects that may occur during clonazepam treatment, talk with your doctor.

Should I expect kidney-related side effects with clonazepam?

No, kidney-related side effects are not likely to occur with clonazepam. These side effects weren’t reported in clinical trials of people taking the drug.

Keep in mind that your kidneys remove clonazepam from your body. If your kidneys aren’t working properly due to kidney disease, for example, the drug can build up in your system. This can increase your risk of side effects. So, your doctor may prescribe a lower dose of clonazepam if you have a kidney problem.

Before starting with clonazepam, be sure to tell your doctor about any kidney problems you have. They can recommend the right dose of clonazepam for you.

What side effects do older adults experience during clonazepam treatment?

Older adults (ages 65 years and older) taking clonazepam usually experience side effects similar to those in younger people taking the drug. However, older people may be at a higher risk of certain side effects, such as confusion or sleepiness.

It’s important to note that clonazepam is broken down and removed from the body by the kidneys and liver. If you’re an older adult, you may have an increased risk of kidney or liver problems. Because of this, your doctor will usually prescribe the lowest possible dose of clonazepam for you. Then your doctor can slowly increase your dose until the right level is reached.

If you’re an older adult taking clonazepam and have questions or concerns about side effects, talk with your doctor or pharmacist.

Before starting treatment with clonazepam, talk with your doctor about any medical conditions that you have.

Boxed warnings

This drug has boxed warnings about the following risks. These are serious warnings from the Food and Drug Administration (FDA).

Other precautions

Be sure to talk with your doctor about your health history before you take clonazepam. This drug may not be the right treatment for you if you have certain medical conditions or other factors that affect your health. These are considered drug-condition or drug-factor interactions. The conditions and factors to consider include:

Kidney problems. Before starting clonazepam treatment, it’s important to tell your doctor about any kidney problems you have. For details, see “Clonazepam: FAQs about side effects” above.

Liver problems. Your body breaks down clonazepam in your liver. If you have a liver problem, such as liver disease, the drug could build up in your body. Too much clonazepam in your system can increase your risk of serious side effects and possibly overdose. Before you start to take clonazepam, it’s important to tell your doctor whether you have any liver problems. They may prescribe a lower dose of clonazepam.

Depression or another mood disorder. In some cases, clonazepam can cause depression or other mood changes. If you already have such a condition, the drug may make your symptoms worse. Before starting clonazepam treatment, tell your doctor if you have depression or another mood disorder. They can help determine whether clonazepam is safe for you.

Porphyria. Clonazepam may worsen symptoms of a genetic condition called porphyria. Before you start taking the medication, it’s important to tell your doctor if you have porphyria. They can help determine the best treatment plan for you.

Allergic reaction. If you’ve had an allergic reaction to clonazepam or any of its ingredients, your doctor will likely not prescribe the drug. Taking clonazepam could cause you to have another allergic reaction. Ask your doctor what other medications may be better options for you.

Seizures. In some cases, clonazepam may increase your risk of seizures. This is especially true if your body has become used to clonazepam. If your dose is abruptly lowered or treatment is stopped, that could increase your risk of a seizure. It’s important that you do not adjust your dose or stop taking clonazepam without your doctor’s approval.

If you have seizures or a seizure disorder, such as epilepsy, tell your doctor before taking clonazepam. They can help determine whether clonazepam is safe for you based on your condition.

Breathing conditions. It’s possible for clonazepam to cause breathing problems. If you already have a breathing condition, such as asthma, the drug may worsen it. Before starting clonazepam treatment, tell your doctor if you have a breathing condition. They can help determine whether clonazepam is a safe treatment option.

Older age. Older adults (ages 65 years and older) taking clonazepam may have a higher risk of side effects than younger people taking the drug. For details, see “Clonazepam: FAQs about side effects” above.

Glaucoma. Clonazepam can worsen symptoms of an eye condition called glaucoma. If you have glaucoma, tell your doctor before taking the drug. They can help determine whether clonazepam is right for you.

Alcohol with clonazepam

Drinking alcohol while taking clonazepam is not recommended. Both alcohol and clonazepam are central nervous system depressants, which means they may cause:

  • sleepiness
  • trouble breathing
  • dizziness
  • coma

In addition, taking clonazepam and drinking alcohol can increase your risk of overdose.

If you have questions about alcohol and clonazepam, talk with your doctor.

Pregnancy and breastfeeding while taking clonazepam

Here’s some information about pregnancy, breastfeeding, and clonazepam.

Pregnancy. There haven’t been enough clinical trials to determine what effects clonazepam may have on a developing fetus. Animal studies showed that congenital anomalies (commonly known as birth defects) occurred when the fetus was exposed to clonazepam. Developmental problems also occurred. However, animal studies don’t always indicate what may happen in humans.

It is known that if clonazepam is taken during pregnancy, the baby may have withdrawal symptoms. These are side effects that can occur when the child stops receiving a drug their body has become dependent on. Examples of clonazepam withdrawal symptoms in newborns can include slow breathing and less muscle tone.

Pregnancy registry. A pregnancy registry is available for clonazepam. A pregnancy registry is a collection of information to show what the effects of a drug may be when taken during pregnancy. This can help determine the safety of a medication during pregnancy. Your doctor can tell you more. To sign up for the registry, call 888-233-2334 or visit its website.

If you’re pregnant or planning to become pregnant, talk with your doctor before taking clonazepam. They can help determine what treatment is right for you.

Breastfeeding. Clonazepam passes into breast milk. This means that a child who is breastfed will be exposed to the medication. However, it’s unknown what effects this may have on a breastfed child.

If breastfeeding or considering it, talk with your doctor before taking clonazepam. They can advise you on the most suitable treatment plan.

* Sex and gender exist on spectrums. Use of the term “female” in this article refers to sex assigned at birth.

Clonazepam has a boxed warning for the risk of misuse and addiction. A boxed warning is the most serious warning from the Food and Drug Administration (FDA). The purpose of a boxed warning is to let prescribers and patients know about the risks of taking a drug.

Misusing a drug means taking it in a way that’s different than how your doctor prescribed it. Misusing a medication can increase your risk of overdose or other serious side effects. Addiction is when you need to take a drug to feel as you usually do, even if it negatively affects your life.

Clonazepam is a type of drug called benzodiazepine. The misuse of benzodiazepines can cause serious side effects, such as:

Misusing benzodiazepines may also, in rare cases, be fatal. If you, friends, family, or a caregiver notice that you have any of these symptoms, your doctor should be consulted right away.

Before you start to take clonazepam, your doctor will recommend a treatment plan for you. It’s important to take the medication exactly as they instruct. You should not change your dose without first consulting your doctor. They’ll likely prescribe the smallest dose of clonazepam for the shortest possible time. This is meant to reduce the risks of misuse and addiction.

You should also tell your doctor if you have a history of drug misuse or addiction. In this case, they may monitor you more frequently than usual while you take clonazepam. Your doctor can also help answer additional questions or concerns you have.

Clonazepam may cause side effects, most of which are mild. However, serious side effects may also be possible from taking clonazepam. Be sure to talk with your doctor if you develop any serious side effects.

If you’d like to learn more about clonazepam, talk with your doctor or pharmacist. They can help answer any questions you have about side effects from taking the drug. You can also ask them about Klonopin, the brand-name version of clonazepam.

A generic drug and its brand-name version contain the same active ingredient, so they’re expected to have the same side effects. Referring to the following articles about clonazepam and Klonopin can provide you with additional information:

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 another 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.