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Mirtazapine for depression

Zispin SolTab

The usual dose is one tablet each day, taken at bedtime.

It may take up to four weeks after starting this treatment before you feel the full benefit. Do not stop taking it, feeling it is not helping.

It is common to feel sleepy when you first start taking mirtazapine.

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About mirtazapine

Type of medicine


Used for

Depression in adults

Also called

Zispin SolTab®

Available as

Tablets, melt-in-the-mouth (orodispersible) tablets, oral liquid medicine

Depression can develop for no apparent reason, or it may be triggered by a life event such as a relationship problem, bereavement, or illness.

Brain cells, called neurons, release a number of chemicals which go on to stimulate other neurons. This leads to electrical impulses which result in the many functions controlled by your brain, including mood. Noradrenaline (norepinephrine) and serotonin are two chemicals released by neurons. Mirtazapine works by increasing the amount of noradrenaline and serotonin available in your brain. This can help ease the symptoms of depression.

Before taking mirtazapine

Some medicines are not suitable for people with certain conditions, and sometimes a medicine may only be used if extra care is taken. For these reasons, before you start taking mirtazapine it is important that your doctor knows:

  • If you are pregnant, trying for a baby or breastfeeding.

  • If you have any heart, liver or kidney problems.

  • If you have low blood pressure (hypotension).

  • If you have ever experienced any problems passing urine.

  • If you have ever had a seizure, or fit.

  • If you have high levels of glucose in your blood (diabetes mellitus).

  • If you have a condition which increases pressure in your eye(s) - for example, glaucoma.

  • If you have had any other mental health problem, in particular psychosis or bipolar disorder.

  • If you have ever had an allergic reaction to a medicine.

  • If you are taking any other medicines. This includes any medicines you are taking which are available to buy without a prescription, as well as herbal and complementary medicines.

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How to take mirtazapine

  • Before you start this treatment, read the manufacturer's printed information leaflet from inside your pack. The manufacturer's leaflet will give you more information about mirtazapine and a full list of side-effects which you may experience from taking it.

  • Take mirtazapine exactly as your doctor has told you to. It is generally prescribed as a once-daily dose, at bedtime. There are several strengths and types of tablet available, so your doctor will tell you which is right for you. This information will also be on the label of the pack you have been supplied with.

  • You can take mirtazapine before or after food.

  • Unless you have been given a melt-in-the-mouth (orodispersible) tablet, in which case see below, you should swallow mirtazapine tablets whole - do not chew or crush the tablets. Take them with a drink of water.

  • If you have been given an orodispersible tablet, these are made to dissolve in your mouth so that you can swallow them without needing a drink of water. Remove the tablet carefully from the wrapper (by peeling back the foil) and place it on your tongue. Make sure your hands are dry before touching the tablet.

  • If you have been prescribed the oral liquid medicine, measure out your dose (using the oral syringe provided) into a glass and take it mixed with some water. Do not mix it with any other drink.

  • If you forget to take a dose, don't worry, just remember to take the next dose when it is due. Do not take two doses together to make up for a missed dose.

Getting the most from your treatment

  • You may feel that mirtazapine is not working for you straightaway. It can take a week or two after starting treatment before the effect begins to build up, and 2-4 weeks before you feel the full benefit. Do not stop taking it after a week or two, feeling it is not helping.

  • Try to keep your regular appointments with your doctor. This is so your doctor can check on your progress. While you are taking mirtazapine you may have thoughts about harming yourself or ending your life. These thoughts may also be associated with your condition. It is very important that you tell your doctor about this if it happens.

  • This medicine may make you feel sleepy. If this happens, do not drive and do not use tools or machines.

  • Your doctor is likely to recommend that you do not drink alcohol while you are taking mirtazapine. It increases the risk of side-effects, such as feeling sleepy.

  • If you buy any medicines, check with a pharmacist that they are safe to take with mirtazapine.

  • There are several types of antidepressants and they differ in their possible side-effects. If you find that mirtazapine does not suit you then let your doctor know, as another may be found that will.

  • Do not stop taking mirtazapine unless your doctor tells you to do so. Stopping treatment suddenly can cause problems and your doctor will probably want you to reduce your dose gradually, over several weeks, if this is necessary. You should expect that a course of treatment will last for several months after your symptoms have eased. This is normal and helps to prevent your symptoms from coming back.

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Can mirtazapine cause problems?

Along with their useful effects, most medicines can cause unwanted side-effects although not everyone experiences them. The table below contains some of the most common ones associated with mirtazapine. You will find a full list in the manufacturer's information leaflet supplied with your medicine. The unwanted effects often improve as your body adjusts to the new medicine, but speak with your doctor or pharmacist if any of the following continue or become troublesome.

Very common mirtazapine side-effects - these affect more than 1 in 10 people who take this medicine

What can I do if I experience this?

Feeling sleepy, dizzy, or tired

If this happens, do not drive and do not use tools or machines. Do not drink alcohol


Drink plenty of water and ask your pharmacist to recommend a suitable painkiller. If the headaches continue, speak with your doctor

Dry mouth

Try chewing sugar-free gum, or sucking sugar-free sweets

Increased appetite and weight

If this becomes troublesome, speak with your doctor

Common mirtazapine side-effects - these affect fewer than 1 in 10 people who take this medicine

What can I do if I experience this?

Feeling sick (nausea), diarrhoea

Stick to simple meals - avoid rich or spicy food. Drink plenty of liquid to replace any lost fluids

Disturbed sleep, feeling anxious, rash, swollen feet and ankles, aches and pains, feeling shaky

If any of these become troublesome, speak with your doctor

If you experience any other symptoms which you think may be due to this medicine, discuss them with your doctor or pharmacist.

How to store mirtazapine

  • Keep all medicines out of the reach and sight of children.

  • Store in a cool, dry place, away from direct heat and light.

  • You can use mirtazapine liquid medicine for six weeks after first opening the bottle. After this time, make sure you have a fresh supply to use.

Important information about all medicines

Important information about all medicines

Never take more than the prescribed dose. If you suspect that you or someone else might have taken an overdose of this medicine, go to the accident and emergency department of your local hospital. Take the container with you, even if it is empty.

This medicine is for you. Never give it to other people even if their condition appears to be the same as yours.

If you are having an operation or any dental treatment, tell the person carrying out the treatment which medicines you are taking.

Do not keep out-of-date or unwanted medicines. Take them to your local pharmacy which will dispose of them for you.

If you have any questions about this medicine ask your pharmacist.

Report side effects to a medicine or vaccine

If you experience side effects, you can report them online through the Yellow Card website.

Further reading and references

Article history

The information on this page is written and peer reviewed by qualified clinicians.

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