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What Are the Side Effects of Mirtazapine?

Mirtazapine is an antidepressant medication approved by the U.S. Food and Drug Administration (FDA), which can also be prescribed for anxiety and insomnia. It comes in both generic form and brand names Remeron (immediate-release tablets) and Remeron SolTab (orally disintegrating tablet).

If you are taking mirtazapine or one of its brands for insomnia or anxiety, you may notice improvement with symptoms within one to two weeks. The National Alliance on Mental Health (NAMI) states, “Improvement in these physical symptoms can be an important early signal that the medication is working.” If taking the medication for depression, it may take from six to eight weeks to feel any change. advises to take the drug at the same time every day and before bedtime because it can cause drowsiness. Mirtazapine is usually tolerated well when compared to other antidepressants. It does come with side effects in which you should be aware.

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Mirtazapine Common Side Effects

Below are common side effects that you might experience. As RxList stresses, if you feel your symptoms, such as depression, anxiety, or insomnia, are worsening, contact the prescribing doctor right away. The side effects are:

  • Weight gain
  • Dry mouth
  • Increased appetite
  • Constipation Weakness
  • Lack of energy
  • Drowsiness
  • Dizziness
  • Disturbance in thinking
  • Swelling of legs, feet, and extremities
  • Strange dreams
  • Confusion
  • Back pain
  • Shortness of breath
  • Frequent urination
  • Tremors

Important Information to Know About Mirtazapine

If you are taking mirtazapine for depression, you should keep taking it, even if you start to feel better. If you suddenly stop taking it, it can cause worsening depression, as Everyday Health notes

When you stop taking mirtazapine abruptly, you might experience withdrawal symptoms.

These are most like the symptoms in which your doctor prescribed it for you. As mentioned on, you may experience flu-like symptoms, anxiety and agitation, and trouble sleeping (insomnia), which can worsen depression.

These are common symptoms of antidepressant withdrawal.

Mirtazapine can be a beneficial medicine to take if you struggle with depression, anxiety, or insomnia.

Woman in  bed with her head in her knees

When taken as directed by your doctor, it can ease the symptoms that disrupt your daily life.

The side effects that might occur can be mild and not be much of a bother every day. If they worsen, you should call your doctor right away.


National Alliance on Mental Illness. Mirtazapine (Remeron). (December 2018) from Mirtazapine. How should I take mirtazapine? (December 28, 2018) from MIRTAZAPINE. What are the side effects associated with mirtazapine? from

Everyday Health. Mirtazapine. Mirtazapine Warnings. (October 24, 2014) from

verywellmind. How Long Does Withdrawal From Antidepressants Last? (February 3, 2020) Retrieved from

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