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How and when to take mirtazapine

Follow your doctor's advice, and the instructions that come with your medicine.

Dosage

The usual starting dose for mirtazapine is 15mg to 30mg a day. This can be increased to up to 45mg a day.

Your doctor may recommend dividing your daily dose into 2 doses of different sizes.

If you have problems with your liver or kidneys your doctor might prescribe a lower dose.

How to take it

You can take mirtazapine with or without food.

Swallow the tablets whole with a drink of water. Do not break, crush or chew them.

Mirtazapine also comes as tablets that melt in your mouth (orodispersible tablets). Put the tablet on your tongue and let it dissolve. You can then swallow it without a drink.

Liquid mirtazapine will come with a plastic syringe or spoon to help you measure out the right dose. If you do not have a syringe or spoon, ask your pharmacist for one. Do not use a kitchen teaspoon as it will not measure the right amount.

You'll usually take mirtazapine once a day. It's best to take it before you go to bed as it can make you sleepy.

If your doctor tells you to take it twice a day, take the smaller dose in the morning and the higher dose before you go to bed.

How long to take it for

Once you're feeling better you're likely to keep taking mirtazapine for several more months.

Most doctors recommend that you take antidepressants for 6 months to a year after you no longer feel depressed.

Stopping your medicine too soon can make depression come back.

If you forget to take it

If you take mirtazapine once a day and miss a dose, skip the missed dose and take the next dose at the usual time. Do not take a double dose to make up for a forgotten dose.

If you take mirtazapine twice a day and forget:

  • your morning dose – take it together with your evening dose
  • your evening dose – do not take it with the next morning dose. Instead skip the missed dose, and then continue the next day with your usual morning and evening doses
  • both doses – skip the missed doses. Continue the next day with your usual morning and evening doses. Do not take an extra dose to make up for a missed dose

If you often forget doses, it may help to set an alarm to remind you. You could also ask your pharmacist for advice on other ways to help you remember to take your medicine.

If you take too much

Taking more than your prescribed dose of mirtazapine can cause problems. You may get symptoms including:

  • feeling sleepy
  • a fast or irregular heartbeat
  • feeling confused or faint

The amount of mirtazapine that can lead to an overdose varies from person to person.

Urgent advice: Contact 111 for advice now if:

  • you've taken more than your prescribed dose of mirtazapine

Go to 111.nhs.uk or call 111

If you need to go to A&E, do not drive yourself. Get someone else to drive you or call for an ambulance.

Take the mirtazapine packet, or the leaflet inside it, plus any remaining medicine with you.

Stopping mirtazapine

If you've been feeling better for 6 months or more, your doctor may suggest coming off mirtazapine.

Your doctor may recommend reducing your dose gradually over several weeks, or longer if you've been taking mirtazapine for a long time.

This is to help prevent you getting any extra side effects as you come off the medicine.

Important

Do not stop taking mirtazapine suddenly, or without talking to your doctor first.

Page last reviewed: 15 February 2022
Next review due: 15 February 2025