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What does it do?

Mirtazapine is used to treat and prevent depression, and sometimes other conditions.

How should you take it?

Take mirtazapine regularly as directed with a glass of water, usually at night-time. Swallow the tablets whole.

What if you forget a dose?

Take the missed dose as soon as possible. If it is close to the time for your next dose, skip the missed dose and carry on as normal. Do not take two doses at the same time.

Can you take other medicines?

Some medicines available without a prescription may react with mirtazapine including:

  • cold and flu medicines containing dextromethorphan (e.g. Robitussin Dry Cough Forte®)
  • other medicines that may cause drowsiness (e.g. pain-killers, anti-nausea and cough/cold medicines – ask your pharmacist)
  • some migraine medicines, such as sumatriptan (e.g. Sumagran Active®) or zolmitriptan (e.g. Zomig®)

Tell your pharmacist or doctor about all medicines or treatments that you may be taking, including vitamins, herbal products (e.g. St John's wort) or recreational drugs (e.g. ecstasy).

What side effects might you notice?

Side EffectsRecommended action

Suicidal thoughts

Change in heartbeat

Muscle twitching or shaking you can’t control, confusion, heavy sweating, fever

Chills, sore throat, tiredness

Tell your doctor immediately

Anxiety

Tell your doctor

Drowsiness, dizziness, weakness

Strange dreams

Dry mouth, change of appetite, weight gain

Joint, muscle or bone aches and pains

Constipation, stomach upset

Tell your doctor if troublesome

If you notice any other effects, discuss them with your doctor or pharmacist.

Other information:

  • Tell your doctor if you have heart, kidney, prostate or liver problems; glaucoma, bipolar disorder, diabetes, or if you have ever had a seizure.
  • Tell your doctor if you are pregnant, planning to become pregnant, or breastfeeding.
  • Mirtazapine can impair your ability to do tasks such as driving or using machines. Alcohol makes this worse. Discuss your risk with your health professional. (search NZTA - Are you safe to drive?)
  • It may take a few weeks for mirtazapine to start working.
  • Feelings of anxiety in the first few weeks of therapy are common, but should get better. Discuss with your doctor.
  • If your depression continues to get worse, see your doctor.
  • Do not stop taking mirtazapine without talking to your doctor first.

This leaflet contains important, but not all, information about this medicine.

Prepared by the PILs Committee at Christchurch Hospital, Canterbury District Health Board, New Zealand. January 2020

For more general information about this sheet annd its contents, see: What does a My Medicines sheet cover?

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About My Medicines

My Medicines Patient Information Leaflets (PILs) contain important, but not all, information about the medicines they describe.

For more information about the sheets, see: What does a My Medicines sheet cover?

My Medicines is developed by a team at the Canterbury District Health Board. Our team is made up of doctors, pharmacists, and a non-medical person to help us keep to plain language. We also discuss our information with specialist health professionals or groups when needed