Overview of Remeron (Mirtazapine) Atypical Antidepressant

Remeron Has Several Potential Side Effects Which May Limit Its Use

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Remeron Antidepressant. BSIP/UIG / Getty Images

Remeron (mirtazapine) is an antidepressant that is chemically unrelated to other antidepressants, which classifies it as an atypical antidepressant. It is FDA approved to treat major depressive disorder in adults, but not depression in people with bipolar disorder. 

How Remeron Works

Remeron operates by increasing the release of serotonin and norepinephrine, two brain chemicals related to depression. It also binds to histamine receptors, which is probably why this medication causes most people to feel tired. At the same time, it does not bind well to receptors associated with side effects that are problematic with some other types of antidepressants, including lowered sex drive, nausea, nervousness, headache, insomnia, and diarrhea.

Remeron is available in tablet form in dosages of 15, 30 and 45 milligrams. It's also available in the same dosages as Remeron SolTabs®, an oral medication that disintegrates on the tongue in a matter of a few seconds. Generic oral Remeron is also available in 7.5 milligrams. 

Remeron Major Precautions and Warnings

Like all other antidepressants, Remeron carries a black box warning relating to the increased risk of suicide and suicidal behavior in children, teenagers, and young adults. 

Remeron also has a slight risk of causing agranulocytosis, a condition in which the white blood cell count is lowered and the body has difficulty fighting off infections.

Other potential serious risks include:

  • triggering a manic episode
  • serotonin syndrome
  • seizures
  • low sodium in the blood (this is called hyponatremia) and may cause a headache, weakness, confusion, and/or problems thinking
  • severe skin reactions (severe rash with swelling of the skin, including the palms and soles; painful reddening of the skin and/or blisters on the body or in the mouth)
  • severe allergic reaction (for example, problems breathing, swelling of the face, hives or blisters)
  • a type of abnormal heartbeat (symptoms like a fast or abnormal heartbeat, dizziness, or feeling like you will pass out may signal this problem). 

It's important to seek medical attention right away if you experience any of the above serious side effects. 

In addition, sleepiness is a common and potentially serious side effect of Remeron, which is why it's taken at bedtime. Due to this sedating effect, Remeron may also affect your thinking, judgment and motor skills. This means driving, using machinery, and doing other tasks that you need to be alert for are not recommended until you know how Remeron affects you.

Alcoholic beverages can worsen the sedation and dizziness some people experience, so you are advised not to drink alcohol while on this medication. You are also advised to avoid benzodiazepines, which are sometimes prescribed for anxiety, seizure, and insomnia because they can also increase these effects.

Common Side Effects of Remeron

These common side effects may go away in time, but if they don't or they are bothersome, be sure to let your doctor know. They include:

  • Dry mouth
  • Weight gain
  • Dizziness
  • Constipation
  • Appetite increase
  • Abnormal dreams

With regards to weight gain and increased appetite, in controlled trials, increased appetite was experienced by 17 percent of patients, and 7.5 percent of patients reported gaining at least 7 percent of their body weight. Anecdotal evidence suggests that significantly greater weight gain is possible. Remeron may also increase blood cholesterol and triglyceride levels. 

A Word From Verywell

An interesting caveat about Remeron is that the sedation that occurs with it is actually increased at lower doses. In other words, sedation is more prominent in people at a dose of 15mg per day than at doses of 30mg or more per day. This is why some doctors may start a person at a higher dose of 30mg (to minimize the sedative effect).

As always, it is important to only take Remeron under the guidance of your doctor and to not alter the dose or stop the medication on your own. Be sure to inform your doctor too of your health problems, especially any heart, liver, or kidney, conditions, as this may affect your use of or dosage of medication. 

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Article Sources
  • FDA. (2009). Medication Guide: Remeron
  • Hirsch M, Birnbaum RJ. (September 2016). Atypical antidepressants: Pharmacology, administration, and side effects. In: UpToDate, Roy-Byrne PP (Ed), UpToDate, Waltham, MA.