Fluoxetine: uses, benefits and side effects

Like other SSRIs, fluoxetine works by helping to restore the balance of serotonin in the brain. It’s thought that low levels of serotonin may contribute to depression, and fluoxetine responds to this by boosting the amount of circulating serotonin available in your system.

The effects of fluoxetine should be seen around four to six weeks after beginning treatment.

Fluoxetine is available as 10mg film-coated tablets, 20mg and 60mg capsules, and also as a 20mg/5ml oral solution.

The usual dose for adults is 20mg a day, although you may be started at a lower dose which is gradually increased to a maximum daily dose of 60mg.

The amount of fluoxetine you need to take depends on the dose that your GP feels will best alleviate your symptoms or particular condition. 

Fluoxetine can be taken as a single dose or in divided doses, during or between meals.

It’s up to you when to take fluoxetine; just make sure you stick to the same time every day. If you’re having trouble sleeping, it’s best to take it in the morning.

Do not crush, break or chew the tablets - take them whole with a glass of water.

If you forget to take a dose, take it as soon as possible unless it’s almost time for your next dose. Do not take two doses together. 

For more advice on taking fluoxetine, be sure to check the Patient Information Leaflet (PIL) included in your medication packaging.

Common side effects of fluoxetine (which happen in more than 1 in 100 people) include:

Serious side effects are rare (less than 1 in 100 people).

Tell your straight away GP if any of these side effects occur:

If you feel as though your course of fluoxetine is causing unwanted side effects, your GP may decide to adjust your dose depending on the severity of the side effects.

1 in 100 people who take fluoxetine will experience side effects, including headaches and dizziness.

When you stop taking fluoxetine, the active drug substances will persist in your body for up to six weeks. This means a new medication can still interact with the fluoxetine that remains in your system.

If you have been prescribed fluoxetine, you should not take:

A full list of interactions with fluoxetine can be found here.

If you have recently taken or are taking any other medication before starting your fluoxetine course, let your GP or pharmacist know as soon as possible.

There are some instances where it may not be safe to take fluoxetine.

Speak to your GP if you are:

You should not take fluoxetine if you are pregnant. Some studies suggest an increased risk for the baby to be born with cardiovascular problems.

It’s also not recommended to take fluoxetine if you are breastfeeding, because it passes into breast milk and has been linked with side effects in breastfed babies.

If you are on a course of fluoxetine, drinking alcohol is not advisable. You may find that booze can cause unwanted side effects such as drowsiness and loss of coordination, so certainly err on the side of caution when you attend work drinks.

Speak with your GP or pharmacist if you intend to drink while taking fluoxetine.