Mirtazapine | Side Effects, Dosage, Uses & More
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Generic Name:

mirtazapine, Oral tablet

All Brands

  • Remeron
SECTION 1 of 5

Highlights for mirtazapine

Oral tablet
1

Mirtazapine is used to treat depression.

2

This drug is available as an immediate-release tablet and a disintegrating (dissolving) tablet you take by mouth.

3

Mirtazapine immediate-release tablet is available as the brand-name drug called Remeron. The orally disintegrating tablet is available as the brand-name Remeron Soltab. Both forms are available as generic drugs.

4

The more common side effects of this drug include sleepiness, increased appetite, weight gain, dry mouth, constipation, dizziness, and strange dreams.

5

In some cases, mirtazapine can cause serious side effects. This includes thoughts of harming yourself. This risk is higher within the first few months of treatment or during dose changes.

IMPORTANT INFORMATION

FDA warning

This drug has a black box warning. This is the most serious warning from the Food and Drug Administration (FDA). A black box warning alerts doctors and patients about drug effects that may be dangerous.

Suicide risk warning. Drugs used to treat depression, including mirtazapine, may cause an increase in suicidal thoughts or actions (thoughts or behaviors of harming yourself). This risk is higher in children, teenagers, or young adults, and within the first few months of treatment or during dose changes. You and your family members, caregivers, and doctor should watch for any new or sudden changes in your mood, behaviors, thoughts, or feelings. Call your doctor right away if you have any of these changes.

Serotonin syndrome

This drug can cause a life-threatening condition called serotonin syndrome. Your risk may be higher if you also take other drugs that have similar effects as mirtazapine. These include antidepressants or triptans, such as sumatriptan and zolmitriptan. Symptoms include agitation, hallucinations (seeing or hearing something that isn’t there), confusion, trouble thinking, coma (being unconscious for a long time), coordination problems, and muscle twitching (overactive reflexes). They also include stiff muscles, racing heartbeat, high or low blood pressure, sweating, fever, nausea, vomiting, and diarrhea. Call your doctor right away if you have these symptoms.

Stopping treatment

Don’t stop taking this drug without talking to your doctor. Stopping it suddenly can cause withdrawal symptoms. These include anxiety, agitation, shaking, tingling or electric shock-like feelings, sweating, nausea, vomiting, strange dreams, dizziness, tiredness, confusion, and headache. If you need to stop taking this drug, your doctor will slowly reduce your dose over time. Your doctor will watch you for withdrawal symptoms when stopping treatment.

Dangerous activities

This drug can cause drowsiness. It may also affect your ability to make decisions, think clearly, or react quickly. You shouldn’t drive, use machinery, or do other activities that require alertness until you know how this drug affects you.

What is mirtazapine?

Mirtazapine is a prescription drug. It’s available as an oral immediate-release tablet or orally disintegrating (dissolving) tablet.

Mirtazapine is available as a generic drug. Generic drugs usually cost less. In some cases, they may not be available in every strength or form as the brand-name version. Talk to your doctor to see if the generic version will work for you.

Mirtazapine may be used as part of a combination therapy. This means you may need to take it with other medications.

Why it's used

Mirtazapine is used to treat depression.

How it works

Mirtazapine belongs to a class of drugs called antidepressants.

More Details

How it works

Mirtazapine belongs to a class of drugs called antidepressants. A class of drugs is a group of medications that work in a similar way. These drugs are often used to treat similar conditions.

It isn’t known exactly how mirtazapine works to treat depression. It may increase the amounts of norepinephrine and serotonin in your brain. These are chemical messengers that affect your mood.

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mirtazapine Side Effects

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More Common Side Effects

The more common side effects of mirtazapine can include:

  • sleepiness

  • increased appetite

  • weight gain

  • dry mouth

  • constipation

  • dizziness

  • strange dreams

If these effects are mild, they may go away within a few days or a couple of weeks. If they’re more severe or don’t go away, talk to your doctor or pharmacist.

Serious Side Effects

Call your doctor right away if you have serious side effects. Call 9-1-1 if your symptoms feel life-threatening or if you think you’re having a medical emergency. Serious side effects and their symptoms can include the following:

  • Suicidal thoughts or actions. Symptoms can include:

    • attempts to commit suicide
    • acting on dangerous impulses
    • acting aggressive or violent
    • thoughts about suicide or dying
    • new or worse depression
    • new or worse anxiety or panic attacks
    • feeling agitated, restless, angry, or irritable
    • trouble sleeping
    • an increase in activity or talking more than normal
    • other unusual changes in behavior or mood
  • Manic episodes. Symptoms can include:

    • greatly increased energy
    • severe trouble sleeping
    • racing thoughts
    • reckless behavior
    • unusually grand ideas
    • excessive happiness or irritability
    • talking more or faster than normal
  • Weakened immune system. Mirtazapine may decrease your white blood cells. White blood cells help your body fight infections. This can make you more likely to get infections. Symptoms can include:

    • fever
    • chills
    • sore throat
    • mouth or nose sores
    • flu-like symptoms, such as body aches, fatigue, and vomiting 
  • Serotonin syndrome. This condition can be life-threatening. Symptoms can include:

    • agitation
    • hallucinations (seeing or hearing something that isn’t there)
    • coma (being unconscious for a long time)
    • confusion
    • trouble thinking
    • coordination problems
    • muscle twitching (overactive reflexes) or stiff muscles
    • racing heartbeat
    • high or low blood pressure
    • sweating or fever
    • nausea, vomiting, or diarrhea
  • Visual problems. Symptoms can include:

    • eye pain
    • changes in vision
    • swelling or redness in or around your eye
  • Seizures

  • Low sodium (salt) levels in your blood. Seniors may be at a higher risk. Symptoms can include:

    • headache
    • weakness or feeling unsteady
    • confusion, trouble concentrating or thinking, or memory problems
  • Sleepiness. It’s best to take mirtazapine close to bedtime.

  • Severe skin reactions. Symptoms can include:

    • severe rash with skin swelling (including on the palms of your hands and soles of your feet)
    • painful reddening of your skin or blisters or ulcers (open sores) on your body or in your mouth
  • Severe allergic reactions. Symptoms can include:

    • trouble breathing
    • swelling of your face, tongue, eyes, or mouth
    • rash, itchy welts (hives), or blisters, alone or with fever or joint pain
  • Increases in appetite or weight

  • High cholesterol and triglyceride levels

  • Rhabdomyolysis (a serious muscle problem). Symptoms can include:

    • muscle aches and pains
    • kidney problems
Pharmacist's Advice
Healthline Pharmacist Editorial Team

You may feel restless and agitated (unable to sit or stand still) for the first few weeks while taking this drug.

This drug may cause drowsiness. It may affect your ability to make decisions, think clearly, or react quickly. You shouldn’t drive, use machinery, or do other activities that require alertness until you know how this drug affects you.

Disclaimer: Our goal is to provide you with the most relevant and current information. However, because drugs affect each person differently, we cannot guarantee that this information includes all possible side effects. This information is not a substitute for medical advice. Always discuss possible side effects with a healthcare provider who knows your medical history.
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mirtazapine May Interact with Other Medications

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Mirtazapine can interact with other medications, vitamins, or herbs you may be taking. An interaction is when a substance changes the way a drug works. This can be harmful or prevent the drug from working well.

To help avoid interactions, your doctor should manage all of your medications carefully. Be sure to tell your doctor about all medications, vitamins, or herbs you’re taking. To find out how this drug might interact with something else you’re taking, talk to your doctor or pharmacist.

Alcohol interactions

The use of drinks that contain alcohol can increase your risk of sleepiness from mirtazapine. This may affect your ability to make decisions, think clearly, or react quickly. If possible, you should avoid alcohol while you’re taking this drug. If you drink alcohol, talk to your doctor.

Medications that might interact with this drug

Drugs you shouldn’t take

Taking certain drugs with mirtazapine may cause serious side effects. You shouldn’t take these medications.These drugs include:

  • Monoamine oxidase inhibitors (MAOIs), such as isocarboxazid, phenelzine, and tranylcypromine. Taking these drugs with mirtazapine can increase your risk of serotonin syndrome. If you stop taking this drug and need to take an MAOI, you must wait 14 days between doing so, and vice versa. If you’re switching from one of these drugs to the other, seek medical help right away if you have symptoms of serotonin syndrome. These include a high fever, uncontrolled muscle spasms, stiff muscles, sudden changes in your heart rate or blood pressure, confusion, or loss of consciousness (pass out).
  • Linezolid and intravenous methylene blue. Taking these drugs with mirtazapine can increase your risk of serotonin syndrome.

Drugs that cause more side effects

Taking mirtazapine with certain medications may cause more side effects. These drugs include:

  • Benzodiazepines, such as diazepam, triazolam, and midazolam. You may have more sedation and drowsiness.
  • Triptans, such as sumatriptan. Ask your doctor whether it’s safe for you to take these drugs together. Taking these medications with mirtazapine may increase your risk of serotonin syndrome. Your doctor should watch you closely when you start taking these drugs together and during dose changes.
  • Lithium. Ask your doctor whether it’s safe for you to take these drugs together. Taking these medications with mirtazapine may increase your risk of serotonin syndrome.
  • Serotonergic medications, such as Fentanyl, tramadol, St. John’s wort. Ask your doctor whether it’s safe for you to take these drugs together. Taking these medications with mirtazapine may increase your risk of serotonin syndrome.
  • Warfarin. You may have an increase in bleeding.  Your doctor will watch you closely if you take these drugs together.

Drugs that have an increased blood level
  • Cimetidine. This drug can increase the levels of mirtazapine in your blood. This may cause more side effects. Your doctor may decrease your mirtazapine dose.
  • Antifungals, such as ketoconazole. This drug can increase the levels of mirtazapine in your blood. This may cause more side effects. Your doctor may decrease your mirtazapine dose.
  • Antibiotics, such as erythromycin. This drug can increase the levels of mirtazapine in your blood. This may cause more side effects. Your doctor may decrease your mirtazapine dose.
  • Protease inhibitors for human immunodeficiency virus (HIV), such as ritonavir. This drug can increase the levels of mirtazapine in your blood. This may cause more side effects. Your doctor may decrease your mirtazapine dose.

Drugs that have a reduced blood level
  • Phenytoin.This drug may reduce the levels of mirtazapine in your blood. Your doctor may increase your dose of mirtazapine.
  • Carbamazepine. This drug may reduce the levels of mirtazapine in your blood. Your doctor may increase your dose of mirtazapine.

Disclaimer: Our goal is to provide you with the most relevant and current information. However, because drugs interact differently in each person, we cannot guarantee that this information includes all possible interactions. This information is not a substitute for medical advice. Always speak with your healthcare provider about possible interactions with all prescription drugs, vitamins, herbs and supplements, and over-the-counter drugs that you are taking.
Mirtazapine warnings
People with a history of mania or bipolar disorder
People with a history of mania or bipolar disorder

Talk to your doctor about whether this drug is safe for you. Mirtazapine may trigger a mixed or manic episode.

People with seizures
People with seizures

Talk to your doctor about whether this drug is safe for you. This drug may make your condition worse. If you have a seizure while taking mirtazapine, talk to your doctor. He or she will decide if you should stop taking it. You may need to stop taking this drug right away or your dose may slowly be lowered over time to avoid withdrawal symptoms.

People with heart problems
People with heart problems

Talk to your doctor about whether this drug is safe for you if you have a history of heart problems. These include angina (chest pain), heart attack, or stroke. Mirtazapine can cause low blood pressure, which can make heart problems worse.

People with glaucoma or other eye problems
People with glaucoma or other eye problems

This drug may dilate your pupils. This may trigger a glaucoma attack. Tell your doctor if you have glaucoma before taking this drug.

People with kidney problems
People with kidney problems

If you have kidney problems or a history of kidney disease, you may not be able to clear this drug from your body well. This may increase the levels of mirtazapine in your body and cause more side effects.

People with liver problems
People with liver problems

If you have liver problems or a history of liver disease, you may not be able to process this drug as well. This may increase the levels of mirtazapine in your body and cause more side effects.

Pregnant women
Pregnant women

Mirtazapine is a category C pregnancy drug. That means two things:

  1. Research in animals has shown adverse effects to the fetus when the mother takes the drug.
  2. There haven’t been enough studies done in humans to be certain how the drug might affect the fetus.

Talk to your doctor if you’re pregnant or planning to become pregnant. This drug should only be used if the potential benefit justifies the potential risk to the fetus.

Women who are breast-feeding
Women who are breast-feeding

Mirtazapine may pass into breast milk and may cause side effects in a child who is breast-fed.

Talk to your doctor if you breast-feed your child. You may need to decide whether to stop breast-feeding or stop taking this medication.

For seniors
For seniors

The kidneys of older adults may not work as well as they used to. This can cause your body to process drugs more slowly. As a result, more of a drug stays in your body for a longer time. This raises your risk of side effects, such as confusion or drowsiness.

For children
For children

It isn’t known if mirtazapine is safe and effective for children younger than 18 years.

When to call the doctor
When to call the doctor

Call your doctor right away if you become pregnant while taking this drug.

If you’ve been taking mirtazapine for more than 4 weeks and you don’t think it’s helping your depression, call your doctor. Don’t stop taking this drug without talking to your doctor first.

allergies
Allergies

Mirtazapine can cause a severe allergic reaction. Symptoms can include:

  • trouble breathing
  • swelling of your face, tongue, eyes, or mouth
  • severe rash with skin swelling, including on the palms of your hands and soles of your feet
  • painful reddening of your skin or blisters or ulcers (open sores) on your body or in your mouth
  • itchy welts (hives) or blisters, alone or with a fever or joint pain

If you have an allergic reaction, call your doctor or local poison control center right away. If your symptoms are severe, call 9-1-1 or go to the nearest emergency room.

Don’t take this drug again if you’ve ever had an allergic reaction to it. Taking it again could be fatal (cause death).

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How to Take mirtazapine (Dosage)

Oral tablet

All possible dosages and drug forms may not be included here. Your dosage, drug form, and how often you take the drug will depend on:

  • your age
  • the condition being treated
  • how severe your condition is
  • other medical conditions you have
  • how you react to the first dose

What are you taking this medication for?

Depression

Generic: mirtazapine

Form: Oral immediate-release tablet
Strengths: 7.5 mg, 15 mg, 30 mg, 45 mg
Form: Orally disintegrating tablet
Strengths: 15 mg, 30 mg, 45 mg

Brand: Remeron

Form: Oral immediate-release tablet
Strengths: 15 mg, 30 mg, 45 mg

Brand: Remeron SolTab

Form: Orally disintegrating tablet
Strengths: 15 mg, 30 mg, 45 mg
Adult dosage (ages 18-64 years)
  • Typical starting dosage: 15 mg taken once per day, usually in the evening before bedtime.
  • Dosage increases: Your doctor will slowly increase your dose every 1-2 weeks. They’ll change your dose based on your depression symptoms.
  • Maximum daily dosage: 45 mg taken once per day
Child dosage (ages 0–17 years)

It hasn’t been confirmed that this drug is safe and effective for use in people younger than 18 years.

Senior dosage (ages 65 years and older)

The kidneys of older adults may not work as well as they used to. This can cause your body to process drugs more slowly. As a result, more of a drug stays in your body for a longer time. This raises your risk of side effects.

Your doctor may start you on a lowered dose or a different dosing schedule. This can help keep levels of this drug from building up too much in your body.

Disclaimer: Our goal is to provide you with the most relevant and current information. However, because drugs affect each person differently, we cannot guarantee that this list includes all possible dosages. This information is not a substitute for medical advice. Always to speak with your doctor or pharmacist about dosages that are right for you.
Pharmacist's Advice
Healthline Pharmacist Editorial Team

Mirtazapine comes with serious risks if you don’t take it as prescribed.

If you stop taking the drug or don’t take it at all

Your depression may get worse. If you suddenly stop taking mirtazapine, you may have withdrawal symptoms. These include:

  • anxiety
  • agitation
  • shaking
  • tingling or electric shock-like sensations
  • sweating
  • nausea
  • vomiting
  • strange dreams
  • dizziness
  • tiredness
  • confusion
  • headache

If you miss doses or don’t take the drug on schedule

Your medication may not work as well or may stop working completely. For this drug to work well, a certain amount needs to be in your body at all times.

If you take too much

You could have dangerous levels of the drug in your body. Symptoms of an overdose of this drug can include:

  • confusion
  • sleepiness
  • memory problems
  • fast heart rate

If you think you’ve taken too much of this drug, call your doctor or local poison control center. If your symptoms are severe, call 9-1-1 or go to the nearest emergency room right away.

What to do if you miss a dose

Take your dose as soon as you remember. But if you remember just a few hours before your next scheduled dose, take only one dose. Never try to catch up by taking two doses at once. This could result in dangerous side effects.

How to tell if the drug is working

You should have decreased symptoms of depression and be in a better mood. Note that it may take 4 weeks before this drug works to treat your depression.

Mirtazapine is used for long-term treatment.

Important considerations for taking mirtazapine
You can take mirtazapine with or without food
You can take mirtazapine with or without food
Take mirtazapine close to bedtime because it may cause sleepiness
Take mirtazapine close to bedtime because it may cause sleepiness
You can cut or crush the immediate-release tablets
You can cut or crush the immediate-release tablets
See Details
Store this drug carefully
Store this drug carefully
See Details
A prescription for this medication is refillable
A prescription for this medication is refillable
See Details
Travel
Travel
See Details
Clinical monitoring
Clinical monitoring
See Details
Not every pharmacy stocks this drug. When filling your prescription, be sure to call ahead.
Not every pharmacy stocks this drug. When filling your prescription, be sure to call ahead.
Insurance
Insurance
See Details

You can cut or crush the immediate-release tablets

You cannot cut or crush the orally disintegrating tablets.

Store this drug carefully

  • Store mirtazapine at room temperature. Keep it between 59°F and 86°F (15°C and 30°C).
  • Keep it away from light.
  • Don’t store this medication in moist or damp areas, such as bathrooms.

A prescription for this medication is refillable

You should not need a new prescription for this medication to be refilled. Your doctor will write the number of refills authorized on your prescription.

Travel

When traveling with your medication:

  • Always carry your medication with you. When flying, never put it into a checked bag. Keep it in your carry-on bag.
  • Don’t worry about airport x-ray machines. They can’t hurt your medication.
  • You may need to show airport staff the pharmacy label for your medication. Always carry the original prescription-labeled box with you.
  • Don’t put this medication in your car’s glove compartment or leave it in the car. Be sure to avoid doing this when the weather is very hot or very cold.

Clinical monitoring

You and your doctor should monitor certain health issues. This can help make sure you stay safe while you take this drug. These issues include:

  • Kidney and liver function.Your doctor may do blood tests to check how well your kidneys and liver are working. If your kidneys or liver aren’t working well, your doctor may lower your dose of this drug.
  • Mental health and behavioral problems. You and your doctor should watch for any unusual changes in your behavior and mood. This drug can cause new mental health and behavior problems. It can also make problems you already have worse.
  • White blood cell counts. This drug can decrease the number of white blood cells that you have. You need white blood cells to fight infections. Your doctor may check your white blood cell count while you’re taking this drug.
  • Cholesterol levels. This drug can increase your cholesterol. Your doctor will check your cholesterol levels while you’re taking this drug.

Insurance

Many insurance companies require a prior authorization for this drug. This means your doctor will need to get approval from your insurance company before your insurance company will pay for the prescription.

Are there any alternatives?

There are other drugs available to treat your condition. Some may be better suited for you than others. Talk to your doctor about other drug options that may work for you.

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How Much Does mirtazapine Cost?

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Lowest price for mirtazapine

Walgreens $5.00
Membership warehouse $11.46
Kroger Pharmacy $11.56
These prices represent the lowest priced national pharmacies for mirtazapine on GoodRx. They may be lower than your insurance.

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These prices represent the lowest priced national pharmacies for mirtazapine on GoodRx. They may be lower than your insurance.

Content developed in collaboration with University of Illinois-Chicago, Drug Information Group

Medically reviewed by Creighton University, Center for Drug Information and Evidence-Based Practice on January 21, 2016

Disclaimer: Healthline 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.
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