Mirtazapine (Remeron, Remeron SolTab) is a generic prescription medication used to treat depression in adults. Mirtazapine comes as an oral tablet and an orally disintegrating tablet. As with other drugs, mirtazapine can cause side effects.

If mirtazapine works for you, your doctor will likely recommend that you take it long term.

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

Mirtazapine can cause certain side effects, some of which are more common than others. 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.

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

  • sleepiness
  • increased appetite
  • dizziness
  • weight gain*
  • nausea*

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

Mild side effects can occur with mirtazapine use. This list doesn’t include all possible mild side effects of the drug. For more information, you can refer to mirtazapine’s prescribing information.

Mild side effects that have been reported with mirtazapine 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 side effects of the medication. If you develop a side effect while taking mirtazapine and want to tell the FDA about it, visit MedWatch.

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

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

If you develop serious side effects while taking mirtazapine, 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:

* Mirtazapine has a boxed warning for this side effect. This is the most serious warning from the Food and Drug Administration (FDA). To learn more, see the “Side effect specifics” section below.

Older adults may be at an increased risk of side effects compared to younger adults taking mirtazapine. Older adults are adults who are 65 years or older. You may also hear older adults referred to as elderly people.

Older adults may metabolize mirtazapine more slowly than younger people. This means that the drug can build up in your body, which may increase the risk of side effects such as confusion or sleepiness.

Due to this risk, doctors may recommend the lowest possible dose for older adults. Then, if more medication is needed, your doctor can increase your dose. This allows your body to adjust to the medication and your doctor to monitor how it affects you.

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

Do different mirtazapine strengths cause different side effects, such as the 7.5-mg, 15-mg, or 30-mg tablets?

Yes, it’s possible that taking a higher strength of mirtazapine may increase your risk of side effects. This is because if you take a higher dose of the drug, your body is exposed to more medication.

For example, if you take a dose of 30 milligrams (mg) of mirtazapine, you may be at a higher risk of side effects than someone taking a 7.5-mg dose of mirtazapine.

If you have questions about the best dose of mirtazapine for you, talk with your doctor.

Does stopping mirtazapine cause withdrawal symptoms?

Yes, it’s possible for mirtazapine to cause withdrawal symptoms. Withdrawal symptoms can happen when you suddenly stop taking certain medications your body is used to. You may be at an especially high risk of withdrawal symptoms if you suddenly stop taking mirtazapine.

Withdrawal symptoms may include:

  • dizziness
  • unusual dreams
  • numbness or tingling
  • agitation (feeling annoyed or restless)
  • anxiety
  • fatigue
  • confusion
  • headache
  • tremors
  • nausea or vomiting
  • sweating

If you’d like to stop taking mirtazapine, talk with your doctor. They can recommend a way to slowly decrease your dose of mirtazapine over time, instead of stopping treatment suddenly. This can decrease your risk of withdrawal symptoms.

Is mirtazapine prescribed for sleep problems? If so, what side effects does the drug cause when prescribed for this use?

Mirtazapine is not approved to help treat sleep problems. However, a side effect of mirtazapine is sleepiness. So, it’s possible that doctors may prescribe mirtazapine off-label. Off-label drug use is when a drug the Food and Drug Administration (FDA) has approved is prescribed for a purpose other than what it’s approved for.

One review showed that mirtazapine helped improve sleep in people with depression. However, since mirtazapine isn’t approved for sleep problems, it’s not known what side effects the drug may cause when it’s prescribed for this use.

If your doctor recommends taking mirtazapine for sleep, talk with them about what side effects may occur.

Learn more about some of the side effects mirtazapine may cause. To find out how often side effects occurred in clinical trials, see the prescribing information for mirtazapine.

Weight gain

You may experience weight gain from taking mirtazapine. Weight gain was a common side effect in clinical trials of the drug. Mirtazapine may cause an increased appetite, which may be the cause of weight gain.

What you can do

If you notice weight gain during your treatment with mirtazapine, talk with your doctor. They may be able to recommend ways to help manage your weight. In some cases, if the weight gain is severe or bothersome to you, your doctor may be able to recommend a different treatment plan for you.

Sexual side effects

It’s possible for mirtazapine to cause sexual side effects. However, sexual side effects were not common in clinical trials of the drug.

Examples of sexual side effects that mirtazapine may cause include delayed orgasm, erectile dysfunction (ED), or increased sex drive.

What you can do

If you notice that mirtazapine may be affecting you sexually, talk with your doctor. In some cases, they may be able to recommend medications to help with your condition. For example, if you have ED from taking mirtazapine, your doctor may recommend another medication, such as Viagra (sildenafil).

Talk with your doctor about any sexual side effects that you experience from mirtazapine. They can help determine how to treat them.

Anger

Mirtazapine can cause changes in mood, including anger. However, this wasn’t a common side effect in clinical trials of mirtazapine.

What you can do

Talk with your doctor if you feel angry when you’re taking mirtazapine. In some cases, your family or friends may notice that you’re angry. In this case, talk with your doctor. They may recommend ways to reduce your anger. In some cases, they may recommend a different treatment option for you.

Nausea

You may have nausea from taking mirtazapine. Nausea wasn’t one of the most common side effects of mirtazapine, but it can occur.

What you can do

If you experience nausea from taking mirtazapine, talk with your doctor. In some cases, taking your medication with food may decrease the nausea that you experience. Your doctor may recommend taking mirtazapine with food to reduce nausea.

Risk of suicidal thoughts and behaviors

Antidepressant medications, including mirtazapine, have a boxed warning for the risk of suicidal thoughts and behaviors in children and young adults. A boxed warning is the most serious warning that the FDA recommends. The purpose of a boxed warning is to alert patients and doctors about the risks of taking a medication.

There’s an increased risk of suicidal thoughts and behaviors in children and adults ages 24 years and younger taking antidepressant drugs. Mirtazapine isn’t approved for use in children.

The risk of suicidal thoughts and behaviors has been reported in people taking antidepressants.

What you can do

If you notice suicidal thoughts or behaviors or worsening mood changes, tell your doctor. Examples of these behaviors may include:

  • worsening depression
  • anxiety
  • feeling hopeless
  • sadness

Also, be sure to tell your doctor if you have a history of mood problems or suicidal thoughts or behaviors. In this case, you may be at an increased risk of this side effect from mirtazapine. Your doctor can help determine whether mirtazapine is a safe treatment option for you.

Allergic reaction

As with most drugs, mirtazapine can cause an allergic reaction in some people. It’s not known how often this side effect occurred in clinical trials.

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 mirtazapine. However, if your symptoms are serious and you think you’re having a medical emergency, immediately call 911 or your local emergency number.

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.

Before starting mirtazapine, tell your doctor about any medical conditions that you have. They can help determine whether mirtazapine is safe for you.

Boxed warning: Suicidal thoughts and behaviors in certain people

This drug has a boxed warning for the risk of suicidal thoughts and behaviors in children and young adults. This is a serious warning from the Food and Drug Administration (FDA). If you have a history of suicidal thoughts or behaviors, tell your doctor before taking mirtazapine. You may be at an increased risk of this side effect. For details, see the “Side effect specifics” section above.

Other precautions

Be sure to talk with your doctor about your health history before you take mirtazapine. This drug may not be the right treatment 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:

Bipolar disorder. If you have a history of bipolar disorder, tell your doctor before taking mirtazapine. This medication can cause mania. And if you have bipolar disorder, you may be at an increased risk of this side effect.

Low white blood cell levels. Mirtazapine can cause low white blood cell levels. If you already have low white blood cell levels, taking mirtazapine may make your condition worse. Your doctor can help determine whether mirtazapine is a safe treatment option for you.

Glaucoma. Tell your doctor if you have glaucoma before taking mirtazapine. This medication can cause glaucoma and may worsen it in people who already have the condition. Your doctor may recommend more frequent monitoring of your condition if you take mirtazapine.

Liver problems. Mirtazapine is broken down in your body by your liver. If you have liver problems, your body may not be able to break down mirtazapine. So, you may be exposed to more medication than usual. This may increase your risk of side effects. Due to this risk, if you have certain liver problems, your doctor may recommend a lower dose of mirtazapine.

Low blood pressure. If you have low blood pressure, tell your doctor before taking mirtazapine. This medication can cause low blood pressure to occur. And if you already have low blood pressure, mirtazapine can cause your blood pressure to become dangerously low. Your doctor may recommend managing your blood pressure before taking this drug.

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

Kidney problems. Mirtazapine is broken down by your kidneys. If you have kidney problems, you may not be able to break down mirtazapine. So, you may be exposed to more medication than usual. This may increase your risk of side effects. Due to this risk, if you have certain kidney problems, your doctor may recommend a lower dose of mirtazapine.

Heart problems or stroke. If you have any history of heart problems or stroke, tell your doctor before taking mirtazapine. Mirtazapine can cause low blood pressure. And, if you have certain heart problems or a history of stroke, this decrease in blood pressure may not be safe. Your doctor can help determine whether it is safe for you to take mirtazapine in this case.

Abnormal heartbeat. If you have an abnormal heartbeat, mirtazapine may make your condition worse. Your doctor can help determine whether mirtazapine is a safe treatment option for you.

Seizures. Although rare, it’s possible for mirtazapine to cause seizures. If you have a history of seizures, taking mirtazapine may make your condition worse. Your doctor can help determine whether mirtazapine is a safe treatment option for you.

High cholesterol or triglycerides. Mirtazapine may cause high cholesterol or high triglyceride levels. If you already have high cholesterol or high triglyceride levels, taking mirtazapine may make your condition worse. Your doctor may recommend ways to manage your cholesterol or triglyceride levels before taking mirtazapine.

Low blood sodium levels. If you have low blood sodium levels, tell your doctor before taking mirtazapine. This medication may cause low blood potassium levels. And, if you already have low blood sodium levels, taking mirtazapine may make your condition worse. Your doctor may recommend managing your sodium levels before starting treatment with mirtazapine.

Alcohol with mirtazapine

Your doctor may recommend avoiding alcohol while you’re taking mirtazapine. This is because alcohol may increase your risk of side effects from mirtazapine. Alcohol and mirtazapine may cause side effects such as sleepiness, dizziness, or nausea.

If you drink alcohol, talk with your doctor to find out whether it’s safe to consume it while taking mirtazapine.

Pregnancy and breastfeeding while taking mirtazapine

At this time, it’s not known if mirtazapine is safe to take during pregnancy or while breastfeeding.

Pregnancy

There aren’t enough studies in humans to determine whether mirtazapine is safe to take during pregnancy. In animal studies, there may be an increased risk of pregnancy loss when pregnant animals were exposed to mirtazapine. It’s important to note that animal studies don’t always indicate what may happen in humans.

However, untreated depression may also have harmful effects on a developing fetus. If you’re pregnant, your doctor can help determine whether it’s safe to take mirtazapine.

There’s also a pregnancy registry for antidepressants, including mirtazapine. A pregnancy registry is a collection of data from pregnant people exposed to medication during pregnancy. The purpose of a pregnancy registry is to determine whether a drug may have an effect on a developing fetus. To sign up for the pregnancy registry, call 844-405-6185 or visit the program website.

Breastfeeding

Mirtazapine is known to pass into breast milk. So a child who is breastfed will likely be exposed to the drug. It’s not known what effects mirtazapine may have on a breastfed child.

If you’re breastfeeding, talk with your doctor before taking mirtazapine. They can help determine the best treatment plan for you.

Mirtazapine can cause side effects. In most cases, side effects of mirtazapine are mild. But it’s also possible to develop serious side effects from this medication.

If you’d like to learn more about mirtazapine, 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 Remeron and Remeron SolTab, the brand-name versions of mirtazapine.

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 can provide you with additional information:

  • More information about mirtazapine. For details about other aspects of mirtazapine, refer to this article.
  • A look at your condition. For details about major depressive disorder, see our depression hub.

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.