Mirtazapine
NHS information about the medicine mirtazapine, including what it's used for, who can take it, how to take it and side effects.
What mirtazapine is for
Mirtazapine is used to treat depression.
It's thought to work by increasing the levels of chemicals in your brain that affect your mood, such as serotonin. This can improve your mood and reduce negative thoughts.
How to take mirtazapine
Mirtazapine can be taken as:
- tablets that you swallow with a glass of water
- tablets that melt on your tongue (orodispersible)
- a liquid (oral solution) that you swallow – this comes with a spoon or syringe for you to measure the correct dose
Your doctor may prescribe a low dose to start with and increase it after a few weeks or so. This reduces the chances of side effects.
You'll usually take mirtazapine once a day before bedtime, as it can make you sleepy.
Your doctor may split your daily dose into 2 doses. Take the smaller dose in the morning and the larger dose before you go to bed.
Always check the packet or leaflet that comes with your medicine. Ask a pharmacist or doctor for advice if you're not sure how to take it or have any problems taking it.
Mirtazapine usually starts working after 1 or 2 weeks and you'll usually take if for at least 4 to 6 months. Tell your doctor if you're not starting to feel better after 2 to 4 weeks.
If you miss a dose of mirtazapine
What to do if you miss a dose of mirtazapine depends on whether you're taking 1 or 2 doses a day.
If you take mirtazapine once a day:
- skip the missed dose and take the next dose at the usual time
- do not take 2 doses to make up for a forgotten dose
If you take mirtazapine twice a day:
- if you forget your morning dose, take it with your evening dose
- if you forget your evening dose or both doses, skip them completely and take the next dose at the usual time the next day
If you take too much mirtazapine
Taking an extra dose of mirtazapine can be dangerous.
Side effects of mirtazapine
Like all medicines, mirtazapine can cause side effects, although not everyone gets them.
Most side effects should ease after a couple of weeks as your body gets used to the medicine, but some can last longer.
Common side effects
Common side effects of mirtazapine include:
- feeling drowsy or sleepy
- headaches
- a dry mouth
- feeling like you want to eat more than usual and putting on weight
- feeling dizzy or shaky
- feeling sick (nausea) or being sick (vomiting)
- diarrhoea
If you feel sleepy or cannot concentrate after taking mirtazapine, do not drive, ride a bike or use machinery until these symptoms have gone away and you feel completely alert.
More about side effects
These are not all the side effects of mirtazapine.
For a full list, see the leaflet inside your medicines packet, or search for your medicine leaflet on the electronic medicines compendium website.
You can report any side effects you get on the Yellow Card Scheme website
Who can and cannot take mirtazapine
Most adults can take mirtazapine.
Mirtazapine is not suitable for everyone. For example, it's not usually recommended for anyone under 18 years.
It may also not be suitable if you have:
- ever had an allergic reaction or serious side effect from mirtazapine
- liver, kidney or heart disease
- epilepsy
- diabetes
- schizophrenia
Before taking mirtazapine, tell your doctor if you have any other medical conditions.
Breastfeeding and mirtazapine
Tell your doctor if you're breastfeeding.
Mirtazapine is sometimes used while breastfeeding. It only passes into your breast milk in very small amounts.
You may be able to continue taking it if the benefits outweigh any possible risks. Your doctor might suggest switching to another antidepressant instead.
It's rare for breastfed babies to get side effects from mirtazapine, but speak to a healthcare professional or call NHS 111 if you have any concerns about your baby.
Pregnancy and mirtazapine
Tell your doctor if you're pregnant or you get pregnant while taking mirtazapine.
Mirtazapine can be used during pregnancy if needed. Your doctor will talk to you about the risks and benefits of taking it while you're pregnant.
You may be advised to give birth in hospital so you and your baby can be closely monitored after you've given birth.
Taking mirtazapine with other medicines, food and drink
There are some medicines, remedies and supplements that may not mix well with mirtazapine.
This includes some types of:
- antidepressants, such as monoamine oxidase inhibitors (MAOIs) and selective serotonin reuptake inhibitors (SSRIs)
- opioids, such as morphine and medicines containing buprenorphine
- painkillers, such as ibuprofen
- epilepsy medicines, such as carbamazepine
- medicines that relax your muscles, such as benzodiazepines
Do not use the herbal supplement St John's wort when taking mirtzapine.
Before taking mirtazapine, tell your doctor if you're taking any other medicines, herbal remedies, vitamins or supplements.
Food, drink and alcohol
You can eat and drink normally when taking mirtazapine.
It's best not to drink alcohol when taking mirtazapine because it can increase the risk of side effects, such as making you feel very drowsy.
Find out more about your medicine
To find out more about your medicine, you can:
- check the leaflet that comes with it
- search for your medicine leaflet on the electronic medicines compendium website
- speak to a pharmacist or doctor for advice – if you recently started taking it, you can get help with newly prescribed medicines from a pharmacist as part of the New Medicine Service
