Mirtazapine (Remeron®)

Author: OncoLink Team
Last Reviewed: July 19, 2022

Pronounce: mir-TAZ-a-peen

Classification: Anti-Depressant, Alpha-2 Antagonist

About: Mirtazapine (Remeron®)

Mirtazapine is a medication used to treat major depressive disorder in adults. Possible side effects of this medication are increased appetite, which can cause weight gain, and sleepiness. Because of these side effects, this medication is sometimes used to help patients who have problems with eating or sleeping.

How This Medication Comes

This medication comes in both a tablet and an orally disintegrating tablet form.

How to take Mirtazapine

This medication is taken by mouth once daily, often at night-time. The tablet can be taken with or without food. If you are taking the orally disintegrating tablet version, make sure to take the medication right away after removing it from the blister pack. The whole disintegrating tablet should be placed on the tongue and allowed to disintegrate (melt or dissolve) without chewing or crushing it. Once it has disintegrated you should swallow the saliva in your mouth.

If you decide that you no longer want to take this medication, you should talk with your provider first. This medication can cause serious side effects if you just stop taking it. Your provider will help create a plan to slowly lower your dose safely.

The blood levels of this medication can be affected by certain foods and medications, so they should be avoided. These include: amphetamines, buprenorphine, buspirone, carbamazepine, cimetidine, clarithromycin, dabrafenib, enzalutamide, idelalisib, ketoconazole, linezolid, lithium, mitotane, opioid and non-opioid pain medications, phenytoin, rasagiline, rifampin, selegiline, tryptophan, and St. John’s Wort, among others. Be sure to tell your healthcare provider about all medications and supplements you take.

You should not drink alcohol while taking this medication. You should not drive a car or operate heavy machinery until you know how this medication affects you.

Storage and Handling

Store this medication in the original container at room temperature. Keep this medication out of reach of children and pets.

Where do I get this medication?

This medication is available through retail/mail order pharmacy. Your oncology team will work with your prescription drug plan to identify an in-network retail/mail order pharmacy for medication distribution.  You can work with your provider’s office if this medication needs a prior authorization.

Insurance Information

Mirtazapine may be covered under your prescription drug plan. Patient assistance may be available to qualifying individuals without prescription drug coverage.  Co-pay cards, which reduce the patient co-pay responsibility for eligible commercially (non-government sponsored) insured patients may also be available. Your care team can help you find these resources if they are available. 

Possible Side effects of Mirtazapine

This medication is given to manage and/or prevent side effects of your cancer treatment. If you are having side effects from this medication you should talk to your team about if this medication is necessary to your treatment or if there are other options to help manage the side effect this medication is treating. These are some of the most common side effects:

Effects on Mood

This medication can cause a variety of changes to a person's mood. If you are experiencing any abnormal changes to your thinking or actions, you should call your provider right away.

  • This medication can cause a person to have thoughts of hurting themselves and to possibly act on those thoughts. If you have any thoughts of suicide, you need to call your provider right away.
  • This medication can also cause somnolence (sleepiness), which can impair judgment, thinking, and also motor skills. Call your provider if you are having any new issues.
  • Mania can be another possible side effect of this medication. Mania is the opposite of depression and is a state of abnormal excitement and energy level.

It is important to be aware of any changes to your mood and to call your provider right away to discuss these changes.

Increased Appetite

This medication can cause an increase in appetite that can help with maintaining and gaining weight. This can be helpful to patients who are having trouble maintaining proper nutrition and weight.

Fatigue & Drowsiness

This medication, depending on your dose and how often you use it, may make you feel sleepy and tired. Please do not drive or operate heavy machinery until you know how this medication affects your ability to do these activities. Additionally, fatigue is very common during cancer treatment and is an overwhelming feeling of exhaustion that is not usually relieved by rest. While on cancer treatment, and for a period after, you may need to adjust your schedule to manage fatigue. Plan times to rest during the day and conserve energy for more important activities. Exercise can help combat fatigue; a simple daily walk with a friend can help. Talk to your oncology care team for helpful tips on dealing with this side effect.

Less common, but important side effects can include:

  • Agranulocytosis: This is a low white blood cell count that causes neutropenia. Symptoms can include fever and infection. You will have your white blood cell count monitored and you should contact your provider if you develop a new cough, sore throat, fever, urgency or pain with urination, or any other sign of infection.
  • Serotonin Syndrome:This side effect can cause a fever, sweating, dilated pupils, diarrhea, higher than normal heart rate, changes in blood pressure, seizures, and agitation. Call your provider right away if you experience any of these side effects.
  • Angle-Closure Glaucoma:This medication can cause your pupils to dilate which in some people can lead to angle-closure glaucoma. You may want to have an exam with an eye doctor to determine if this may be an issue for you.
  • Heart Problems: This medication can cause slow or abnormal heartbeats, or an abnormal heart rhythm called QT prolongation. Notify your oncology care team right away if you feel abnormal heartbeats or if you feel dizzy or faint.
  • Allergic Reactions:This medication can cause an allergic reaction including rash, hives, swelling, or trouble breathing. Contact your provider right away if you experience any of these side effects.

Reproductive Concerns

You should consult with your provider before becoming pregnant or fathering a child while on this medication. You should consult with your healthcare team before breastfeeding while receiving this medication.