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This page explains what mirtazapine is used for, how it works, its risks and whether there are any other treatment options available in its place.

Looking for a medicine?

Visit healthdirect’s list of medicines that contain mirtazapine to find out more about a specific medicine.

What is mirtazapine?

Mirtazapine is an antidepressant medicine. To get mirtazapine, you must have a prescription written for you by a doctor.

What is mirtazapine used for?

Mirtazapine is mainly used to treat depression or to prevent it from occurring again.

Your doctor might prescribe mirtazapine for another reason. If you are unsure about why you are taking mirtazapine, ask your doctor.

How does mirtazapine work?

Medical experts believe mirtazapine works by balancing chemicals in the brain that are thought to affect mood and emotions. The chemicals involved are serotonin and noradrenaline.

What forms of mirtazapine are available?

Mirtazapine is the name of the active ingredient. It is available in many different brands, which have different:

  • names
  • appearances (size, shape or colour)
  • forms (tablets and disintegrating tablets)
  • packaging

No matter which brand you are prescribed, mirtazapine works in the same way to treat depression.

What are the possible side effects of mirtazapine?

Common side effects of mirtazapine include:

  • drowsiness and tiredness
  • increased appetite and weight gain
  • fluid retention and swelling
  • weakness
  • headaches

Tell your doctor if you have rare but serious side effects of mirtazapine, which include:

  • itching or a skin rash
  • low sodium levels
  • feeling extremely restless and an overwhelming urge to always be moving
  • numbness in the mouth
  • unusual changes in behaviour
  • eye pain
  • muscle pain
  • weakness
  • nausea or vomiting

If you experience a serious or life-threatening side effect, you should immediately call triple zero (000).

Each person responds to medicines differently. Just because a side effect is listed does not mean you will experience it. Even if you experience a side effect, you and your doctor will need to weigh up the medicine's benefits against its risks before deciding what to do. This could be deciding to make no changes, change the dose or switch to another treatment option.

This is not a full list of side effects for mirtazapine. For more information on the side effects and risks, read the Consumer Medicine Information (CMI) for the brand of mirtazapine you are taking or talk to your doctor or pharmacist.

If you are planning to stop taking mirtazapine, talk to your doctor. It is important not to stop mirtazapine suddenly, as it may cause nausea, headache, dizziness and anxiety.

When should I speak to my doctor?

Speak to your doctor if you:

  • experience side effects that trouble you
  • have signs of an allergic reaction
  • have a health condition or are taking medication that may affect how your body reacts to mirtazapine
  • become pregnant or start breastfeeding

See the CMI for full details about when to speak with your doctor before or after you have started taking mirtazapine.

Are there alternatives to mirtazapine?

Your doctor might prescribe another type of antidepressant medicine or suggest that you try psychological therapy, such as cognitive behaviour therapy (CBT).

There might be other approaches that can help, such as getting regular exercise and looking for pleasurable things to do each day. You can undertake CBT and other treatments in combination with antidepressant medicine or alone.

More information

Asking about your treatment or medication is important to help you understand your options. Read our guide to important questions to ask your pharmacist or doctor before taking a medicine.

You can also visit healthdirect's list of medicines that contain mirtazapine to read the CMI for the brand of mirtazapine prescribed.

Learn more here about the development and quality assurance of healthdirect content.

Last reviewed: December 2020

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