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Drug Profile

The information on this site is intended to supplement and enhance, not replace, the advice of a physician who is familiar with your medical history. Decisions about your health should always be made ONLY after detailed conversation with your doctor.

Limited Use [what does this mean?]
Generic drug name: mirtazapine (mir TAZ a peen)
GENERIC: available FAMILY: Other Drugs for Depression
Find the drug label by searching at DailyMed.

Pregnancy and Breast-feeding Warnings [top]

Pregnancy Warning

This drug caused harm to developing fetuses in animal studies, including fetal and neonatal deaths and decreased birth weights. Use during pregnancy only for clear medical reasons. Tell your doctor if you are pregnant or thinking of becoming pregnant before you take this drug.

Breast-feeding Warning

No information is available from either human or animal studies. Since it is likely that this drug, like many others, is excreted in human milk, you should consult with your doctor if you are planning to nurse.

Safety Warnings For This Drug [top]



Antidepressants increased the risk of suicidal thoughts and behavior in children and young adults in short-term studies. Patients of all ages who are started on antidepressant therapy should be monitored closely for clinical worsening and emergence of suicidal thoughts and behaviors. Mirtazapine is not approved for use in pediatric patients.

Sexual Dysfunction

All of the SSRI antidepressants have been shown to commonly cause sexual dysfunction in both men and women. In a large prospective study of over 6,000 men and women, sexual dysfunction occurred 36–43% of the time, depending on the drug. Types of sexual dysfunction include problems of desire (libido: sexual interest or drive), arousal (erectile function in men, lubrication in women) and release (ejaculation/orgasm in men and orgasm in women). Strategies to cope with this problem include decreasing the dosage to the lowest effective level; a drug holiday for patients in whom compliance is not a problem; if acceptable to the patient and partner, seeing if the sexual dysfunction resolves without further intervention.[1]

Newer Antidepressants and the Risk of Suicide in Children Less than 18 Years of Age

The FDA and the drug regulatory authorities in Canada and the UK have warned about the possibility of both suicidal ideation and suicide attempts seen in clinical trials of the newer antidepressant drugs, including the selective serotonin reuptake inhibitors (SSRIs), mirtazapine (REMERON), and venlafaxine (EFFEXOR), in children less than 18 years of age.[2],[3],[4]

Facts About This Drug [top]

Mirtazapine (REMERON) is used to treat major depression. Mirtazapine resembles a hybrid of other types of antidepressants, namely tricyclic antidepressants and selective serotonin reuptake inhibitors (SSRIs). Mirtazapine blocks receptors of the neurotransmitters serotonin and norepinephrine.

We have designated mirtazapine as Limited Use. For patients who need an antidepressant drug, we recommend trying one of the newer SSRIs (for example, fluoxetine [PROZAC, SARAFEM, SELFEMRA]) first, as...

Mirtazapine (REMERON) is used to treat major depression. Mirtazapine resembles a hybrid of other types of antidepressants, namely tricyclic antidepressants and selective serotonin reuptake inhibitors (SSRIs). Mirtazapine blocks receptors of the neurotransmitters serotonin and norepinephrine.

We have designated mirtazapine as Limited Use. For patients who need an antidepressant drug, we recommend trying one of the newer SSRIs (for example, fluoxetine [PROZAC, SARAFEM, SELFEMRA]) first, as these are the safest antidepressants. If symptoms do not improve sufficiently with use of an SSRI and remain severe, further treatment with other antidepressants is warranted.

Published information about this drug is sparse. With so many other antidepressants available, it is wiser to use an antidepressant with better-known safety and effectiveness.

Mirtazapine is not recommended for women who are pregnant or for children younger than 18.

Adverse effects

Older adults and those with liver or kidney problems may need a lower dose of mirtazapine. More than half of the people who take mirtazapine experience prolonged, and often severe, drowsiness.


Mirtazapine can cause a blood disorder that lowers the number of white blood cells. Called agranulocytosis, it is a serious, sometimes fatal, adverse effect. The Adverse Drug Reactions Advisory Committee of Australia reported in 2007 that since 2001 it had received reports of 36 patients with blood disorders associated with mirtazapine. Agranulocytosis was reported in five of these patients.[5]

Serotonin syndrome

Another potentially life-threatening effect of mirtazapine is serotonin syndrome, which happens when there is an excess of serotonin, a naturally occurring nerve transmitter. Excess serotonin is usually the result of taking two or more drugs that have an effect on serotonin — such as SSRIs. Symptoms of serotonin syndrome include sweating, shivering and incoordination. (Read more in the April 2008 issue of Worst Pills, Best Pills News.)

Neuroleptic malignant syndrome

In December 2011, the Food and Drug Administration (FDA) updated the product label of mirtazapine to warn that potentially life-threatening neuroleptic malignant syndrome (NMS) could occur as a result of using the drug alone or with subsequent use of serotonergic drugs (such as triptans), drugs that make the metabolism of serotonin more difficult, or antipsychotics or other dopamine antagonists.[6]

Symptoms of NMS can include extremely high body temperature (hyperthermia), heavy sweating, fast heart rate, fast respiratory rate, rapidly fluctuating blood pressure, impaired consciousness, tremor, and rigid, stiff muscles.

Antidepressants and pregnancy

On Aug. 9, 2004, Health Canada, an agency similar to the FDA, issued a public advisory warning to Canadians that newborns may be adversely affected when their mothers take an SSRI or other newer antidepressants during the third trimester of pregnancy. Health Canada reported that some newborns whose mothers took these drugs during pregnancy have developed complications at birth requiring prolonged hospitalization, breathing support and tube feeding. The symptoms reported include feeding and breathing difficulties, seizures, muscle rigidity, jitteriness and constant crying. In most cases, the mothers were prescribed newer antidepressants during the third trimester of pregnancy.[7]

Studies show ...

A randomized, double-blind, placebo-controlled study found that the use of mirtazapine in patients diagnosed with generalized social anxiety disorder was not effective. The study was reported in the September 2010 International Clinical Psychopharmacology journal and included 60 patients.[8]

In 2011, the medical journal Lancet published a randomized, multicenter, double-blind, placebo-controlled study that evaluated the effects of sertraline (ZOLOFT) and mirtazapine on depression in patients with dementia. The results of the study demonstrated that, in patients with dementia who are depressed, the use of these antidepressant drugs did not show a benefit over the use of a placebo.[9]

In March 2014, Health Canada and the manufacturer of mirtazapine issued safety information noting that cases of abnormal heart rhythm or irregular heartbeats have been reported in patients taking mirtazapine.[10]

In May 2014, Prescrire International published an article with information from the World Health Organization pharmacovigilance database on 47 reported cases of rhabdomyolysis, a condition involving breakdown of muscle tissue that causes acute kidney failure, associated with mirtazapine use.[11]

In 2021, The Lancet published results of a randomized, placebo-controlled clinical trial showing that mirtazapine was not was not effective for treating agitation and led to a higher risk of death in patients with dementia.[12]

In 2021, The British Journal of Clinical Pharmacology published a study showing that mirtazapine was associated with an increased risk of developing low levels of thyroid hormone in the blood .[13]

In 2023, Journal of Psychiatric Practice published a systematic review of nine case reports of pancreatitis (inflammation of the pancreas) associated with mirtazapine.[14]

Other regulatory actions surrounding mirtazapine

2004: In October, the FDA issued a public health advisory requiring manufacturers to add a black-box warning (see "FDA Black-Box Warning" at the top of this page) to the product label for all antidepressants that included information on adverse effects such as suicidal thoughts, agitation and impulsivity. A black-box warning is the strongest type of warning that the FDA can require.

The FDA also required that a Medication Guide be given to patients receiving this drug, advising them of the risks and of precautions that can be taken. Click here to view the Medication Guide for mirtazapine.

2007: The FDA announced in May that it would require new warnings concerning the increased risk of suicidal thoughts and behavior in young adults ages 18 to 24 during the first one to two months of treatment with antidepressants. The agency required the new warnings to be black-box warnings printed on the product labels for all antidepressants sold in the United States. The warnings amended an existing black-box warning for children and adolescents.[15]

The FDA-approved product label for antidepressant drugs sold in the United States carries the following statement:

Suicide: The possibility of a suicide attempt is inherent in major depressive disorder and may persist until significant remission occurs. Close supervision of high-risk patients should accompany initial drug therapy. Prescriptions for Drug X should be written for the smallest quantity of tablets consistent with good patient management, in order to reduce the risk of overdose.

Before You Use This Drug [top]

Tell your doctor if you have or have had:

  • allergies to drugs
  • heart, kidney, or liver problems
  • seizures
  • pregnancy or are breast-feeding
  • phenylketonuria (some brands contain aspartame)

Tell your doctor about any other drugs you take, including aspirin, herbs, vitamins, and other nonprescription products.

When You Use This Drug [top]

  • Do not drink alcohol or use other drugs that can cause drowsiness.
  • Until you know how you react to this drug, do not drive or perform other activities that require alertness.
  • You may feel dizzy when rising from a lying or sitting position. When getting out of bed, hang your legs over the side of the bed for a few minutes, then get up slowly. When getting up from a chair, stay beside the chair until you are sure that you are not dizzy.
  • Have your doctor reassess your need to continue taking mirtazapine periodically.
  • If you plan to have any surgery, including dental, tell your doctor that you take this drug.
  • Tell your doctor immediately if you have fever, chills, sore throat, or ulcers on mucous membranes.

How to Use This Drug [top]

  • If you miss a dose, take it as soon as you remember, but skip it if it is almost time for the next dose. Do not take double doses.
  • Do not share your medication with others.
  • Take the drug at the same time(s) each day.
  • Take with or without food.
  • Swallow half or whole tablets, according to dose. Take at bedtime.
  • Do not suddenly stop taking this drug. Check with your doctor.
  • Store at room temperature with lid on tightly. Do not store in the bathroom. Do not expose to heat, moisture, or strong light. Keep out of reach of children.

Interactions with Other Drugs [top]

The following drugs, biologics (e.g., vaccines, therapeutic antibodies), or foods are listed in Evaluations of Drug Interactions 2003 as causing “highly clinically significant” or “clinically significant” interactions when used together with any of the drugs in this section. In some sections with multiple drugs, the interaction may have been reported for one but not all drugs in this section, but we include the interaction because the drugs in this section are similar to one another. We have also included potentially serious interactions listed in the drug’s FDA-approved professional package insert or in published medical journal articles. There may be other drugs, especially those in the families of drugs listed below, that also will react with this drug to cause severe adverse effects. Make sure to tell your doctor and pharmacist the drugs you are taking and tell them if you are taking any of these interacting drugs:

Central nervous system (CNS) depressant drugs, including alcohol, antidepressants, antihistamines, antipsychotics, some blood pressure medications (reserpine, methyldopa, beta-blockers), motion sickness medications, muscle relaxants, narcotics, sedatives, sleeping pills, and tranquilizers.

CATAPRES, Clonidine, diazepam, moclobemide, pargyline, VALIUM.

Do not take mirtazapine within 14 days after stopping or starting any of these monoamine oxidase (MAO) inhibitors: deprenyl, ELDEPRYL, furazolidone, FUROXONE, isocarboxazid, MARPLAN, MATULANE, NARDIL, PARNATE, phenelzine, procarbazine, selegiline, tranylcypromine.

Adverse Effects [top]

Call your doctor immediately if you experience:

  •   agitation or anxiety
  •   chills, shivering
  •   excitement or increased or decreased movement
  •   apathy
  •   confusion or abnormal thinking
  •   dizziness
  •   fever
  •   incoordination
  •   inflammation or sores in mouth
  •   seizures
  •   sore throat
  •   suicidal thoughts
  •   sweating
  •   twitching
  •   menstrual pain or missed periods
  •   decreased sexual ability
  •   mood or mental changes
  •   shortness of breath
  •   swelling of face
  •   skin rash
  •   decreased movement

Call your doctor if these symptoms continue:

  •   constipation
  •   drowsiness
  •   dry mouth
  •   dizziness
  •   weakness
  •   increased appetite, weight gain
  •   abdominal pain
  •   abnormal dreams
  •   back pain
  •   frequent urge to urinate
  •   increased sensitivity to touch and pain
  •   increased thirst
  •   low blood pressure
  •   muscle pain
  •   nausea, vomiting
  •   trembling, shaking

Periodic Tests[top]

Ask your doctor which of these tests should be done periodically while you are taking this drug:

  blood tests

last reviewed January 31, 2024