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What are the Common Mirtazapine Side Effects?

Victoria Bonanni
Victoria Bonanni

Mirtazapine is a tetracyclic antidepressant medication most often prescribed to treat depression. It is available in a tablet form that can be swallowed and in an orally disintegrating tablet form. While mirtazapine side effects can be as ordinary as drowsiness and dizziness, it also is believed that those side effects can be as uncommon as increasing suicidal thoughts and actions.

Not everyone who takes the medication will suffer mirtazapine side effects, but some likely will. Common but less serious side effects include having abnormal dreams or thoughts, confusion, nausea, vomiting, dizziness, drowsiness, dry mouth, flu-like symptoms — including fever, chills and a sore throat — constipation, weakness, increased appetite and the corresponding weight gain. More serious mirtazapine side effects include mouth sores, chest pain, a rapid heartbeat, new or worsening agitation, panic attacks, restlessness or the inability to sit still, aggressiveness, impulsiveness, irritability, an exaggerated feeling of well-being, seizures, severe headache, sluggishness, tremors, unusual or severe mood changes, and increased depression. A person suffering mirtazapine side effects also may have trouble sleeping, whether falling asleep or staying asleep, and he may suffer red, swollen, blistered, or peeling skin,

Mirtazapine might cause mouth sores.
Mirtazapine might cause mouth sores.

Severe allergic reactions — including a rash, hives, itching, difficulty breathing, tightness of the chest, or swelling of the mouth, face, lips, or tongue — also are possible for people taking mirtazapine. Patients who have had a heart attack, low blood pressure, heart or liver disease, or high cholesterol should disclose those conditions to the prescribing doctor. The doctor should also be informed if the patient is pregnant, may become pregnant, or is breastfeeding. A patient should also tell his doctor of all other medications, vitamins and herbal treatments being used — especially diazepam and monoamine oxidase (MAO) inhibitors such as isocarboxazid, phenelzine, selegline, or tranylcypromine — or if the patient has stopped using an MAO inhibitor within the past 14 days. Full disclosure of all medications and treatments will help the doctor to decide if mirtazapine is an appropriate treatment.

Hives may indicate a medication allergy.
Hives may indicate a medication allergy.

As of 2008, mirtazapine side effects included the possibility that young patients would experience suicidal thoughts and, possibly, try to act on those thoughts. The medication began carrying a warning that patients under the age of 24 might experience such a side effect, though it is not thought that older patients are likely to suffer the same dangerous side effect. A patient is more susceptible to mirtazapine side effects at the beginning of treatment and when the dosage is changed, so it may be necessary for the patient to visit his prescribing doctor more frequently at those times. Patients also should avoid driving vehicles or using machinery until they know how mirtazapine can affect them. Patients taking mirtazapine should contact their doctor at the first sign of a serious side effect.

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Discussion Comments


I've been taking 15mg of zopiclone for 10 years nightly; 45mg nightly for psatyr of mirtazapine and now 60mg of fluoxetine. Please help me someone. I know this is not good for me.

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    • Mirtazapine might cause mouth sores.
      By: Antonio Gravante
      Mirtazapine might cause mouth sores.
    • Hives may indicate a medication allergy.
      By: Jürgen Fälchle
      Hives may indicate a medication allergy.
    • Dizziness can be a side effect of mirtazapine.
      By: JPC-PROD
      Dizziness can be a side effect of mirtazapine.
    • Weight gain is a common side effect of mirtazapine.
      By: Rostislav Sedlacek
      Weight gain is a common side effect of mirtazapine.