HeadMeds gives young people in the United Kingdom general information about medication. HeadMeds does not give you medical advice. Please talk to your Doctor or anyone else who is supporting you about your own situation because everyone is different. Please read more important details about our site.

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Return to Fluoxetine overview
  1. Use and Action
  2. Warnings and side effects
  3. Sex, drink, weight and everything else
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Taking Melatonin, Fluoxetine and Sertraline
I think it’s really important to understand that medications aren’t a ‘one size fits all’ type of thing.

You can drink some alcohol while taking fluoxetine

  • You can continue to drink some alcohol while taking fluoxetine, but it is best to keep it in moderation. As fluoxetine can sometimes cause drowsiness as a side effect, it is possible that alcohol might make you feel more drowsy than usual.
  • Drinking alcohol every day, however, can make the symptoms of depression worse and you will not feel the benefit of your medicine.
  • Side-effects might make you sleepy or you might lose your focus when you first start taking fluoxetine.
  • This could be dangerous if you drive or use machines or do anything that needs a lot of focus.
  • So, during the first few days, it might be best to stop drinking alcohol until you see how the medicine affects you, or until the effects pass.

Do not drive or ride a bike just after you start taking fluoxetine

  • Taking fluoxetine may affect your concentration to do things like driving a car, riding a bike, using machines, or anything else that needs a lot of focus.
  • It might be best to stop doing these things for the first few days, until you know how it affects you or until the effects pass.
  • You have to make sure that you are safe to drive.
  • You could go and practise emergency stops in a safe place, or get a friend or family member to go with you and see if they notice a difference in your driving.
  • Do not worry - most people drive as normal while taking fluoxetine.

Try not to take fluoxetine for the first time just before your exams

  • Taking fluoxetine may affect your concentration to do things that need a lot of focus, like exams.
  • You should talk to your doctor about any future exams if you are starting fluoxetine.
  • You might decide together to delay starting it until you have done them. If they are more than a month away, however, you might find that it is better to start fluoxetine to lift your mood and improve your motivation to study.
  • Do not worry - most people do exams as normal while taking fluoxetine.

Fluoxetine can make it hard to concentrate

  • Taking fluoxetine may affect your concentration, and your ability to do anything that needs a lot of focus.
  • After the first few days you will know how it affects you, or the side-effect might get better.

Fluoxetine is not a banned substance in sport

  • Fluoxetine is not a banned substance in sport.
  • Taking fluoxetine may affect your concentration to do things like riding a bike, competitive gymnastics, or anything else that needs a lot of focus.
  • It might be best to stop such sports for the first few days, until you know how it affects you or the effects get better.
  • Do not worry - most people do sports as normal while taking fluoxetine.

Your weight can be affected by fluoxetine 

  • A side-effect of fluoxetine can be not feeling as hungry as normal, which might lead to weight loss.
  • It is very difficult to know how it will affect each person who takes it.
  • Talk to your doctor about this if it worries you.

Fluoxetine may make you sleepy 

  • You can feel drowsy in the first few days of taking fluoxetine. It should, however, get better after the first week or two.
  • If you feel very sleepy, and you’ve been taking it for more than a month, you should go back to the doctor and see what else you could do.

Let your family and friends know you are taking fluoxetine so they can support you and help you look out for side effects

  • The side-effects of fluoxetine might put a strain on your friendships and relationships, especially in the first few days of taking it.
  • You may become more anxious, for example, or it may make you irritable.
  • These side-effects should get better after a few days.
  • After a month you should be getting the good effects of fluoxetine, and that should improve your relationships in itself.
  • It might actually be a great idea to choose a good friend to tell about your medicine when you start taking it. (Or - even better - to take a friend with you to the doctor before you start taking the medicine!)
  • They could look at the medicine leaflet, or at this website.
  • They could then help you to understand whether the medicine changes your behaviour, or gives you side-effects (sometimes it is hard for us to see it ourselves).

Fluoxetine can have side-effects that might affect your sex life

The good effects of fluoxetine may, after a while, have a good effect on your sex life as your mood lifts and you become interested in life and relationships again.

Some of the possible negative side effects include:

  • Men might get painful erections (but this is rare), or problems with getting hard (getting an erection) and coming (ejaculating).
  • Men might get a painful erection that lasts for a long time (priapism); they need to go to hospital straight away for treatment
  • Women might have some bleeding from their vagina
  • Women might not come (reach orgasm) the same way as before
  • Both men and women might see some growth in their breasts, and some milk flow (but this is rare).
  • You may have a lower sex drive
  • If you lose weight, or get other physical side-effects, you may just not feel as sexy as before

These effects should pass after the first couple of weeks. If they do not, and this is a problem for you, go back to the doctor and see what else you could try.

Fluoxetine does not seem to affect human fertility

Talk to your doctor about your fluoxetine if you are trying to get pregnant

  • There does not appear to be any fertility problems with fluoxetine.

Women who are planning a pregnancy should talk to their doctor about their options.

It is important to stay well during the pregnancy, so the option of continuing with fluoxetine will need to be considered as well as the option of stopping it. An alternative medicine may also be considered. Please see below for more information.

You need good contraception when you are taking fluoxetine

  • You should use good contraception when you are taking fluoxetine. This is because there is a slightly higher risk of problems in the developing baby if you take fluoxetine in the early stages of pregnancy. However fluoxetine and related antidepressants (known as SSRIs) are thought to be better choices if you need antidepressant medicine.
  • If you do become pregnant while you are on fluoxetine, you should carry on taking the medicine and go back to your doctor as soon as possible, to see if you should change or stop your medicine.
  • Remember that you need to stay well through your pregnancy, and you may need a medicine to help you to do that.

Fluoxetine may cause heart problems in the developing baby, and other symptoms in newborn babies

Women taking fluoxetine who are planning a pregnancy should talk to the doctor about their options. If you become pregnant whilst taking fluoxetine, you should also talk to your doctor about this.

The doctor will help you to weigh up the options. When taken during pregnancy, fluoxetine can sometimes cause problems in developing or newborn babies (please see below for more information).

However, it is important that you stay well during pregnancy and afterwards, and for some women it may be best to continue taking fluoxetine during the pregnancy and afterwards. Studies show that changing to a different antidepressant (even to another SSRI) once you are pregnant is not as good as staying with the one you are already taking.

  • There may be a slightly higher risk of heart problems in the baby if you take fluoxetine in the early stages of pregnancy.
  • If you and your doctor agree for you to continue taking fluoxetine during your pregnancy, then you should tell your midwife that you are taking it before you give birth.
  • If fluoxetine is taken in the last 5 months of a pregnancy, it can cause a serious condition called persistent pulmonary hypertension of the newborn (PPHN). This can make the baby breathe faster and look a bit blue in colour. PPHN affects around 12 in 1000 babies born to mums who take SSRIs. PPHN also happens in around 2 in 1000 births to babies whose mums haven’t taken any antidepressants.
  • PPHN happens in the first 24 hours after birth. You will need help from the midwife and doctors, so it is better if they are looking out for symptoms.
  • The newborn baby may also develop withdrawal effects, which might not happen straight away. Therefore, you should look out for them over the first few days after the baby is born:
  • Shaking
  • Being irritable and crying a lot
  • Having difficulty sleeping or sucking 

Fluoxetine can be passed to the baby in breast milk

  • Remember that it is important for you to remain well whilst you are bonding with and looking after your baby. For this reason, it may be best to take medicine for your mental health when breastfeeding.
  • Fluoxetine is passed to the baby in breast milk, and side effects have been seen in breastfed babies. The main one is likely to be colic.
  • The amount of fluoxetine in breast milk is usually around 7% of the mum’s dose, but it can build up over time. This is because fluoxetine is hard for your baby to get rid of. This does not mean breastfeeding will be a problem but do look out for side effects
  • If your baby was premature or has health problems, then you may be best to not breastfeed as your baby will likely struggle even more to get rid of the fluoxetine.
  • Talk to your doctor or midwife about your feeding options.
  • Make sure that your doctor, nurse, or health visitor checks your baby for any side effects. These can include:
  • Being extra sleepy
  • Having colic
  • Feeding problems
  • Poor weight gain
  • You may also need to consider bottle feeding with formula milk if there are any problems with breastfeeding whilst taking medicines.

Fluoxetine may slow down body growth and sexual development in young people

  • Fluoxetine has shown some effects of slowing growth and delaying sexual development (puberty) in a small number of children and young people.
  • Your doctor should check your growth while you are taking it.
  • If this worries you, talk to your doctor or pharmacist about it.

Reference sources

Search www.medicines.org.uk to find patient information leaflets and prescribing information on fluoxetine. Capsules and liquid are listed separately. The SmPC lists all the inactive ingredients in the product so you can check against any allergies. If you are still unsure about this then speak to your pharmacist.

  • British National Formulary (BNF) and British National Formulary for children. Download the BNF/BNFC app (blue background) on to your mobile device. No longer available for public access via the web
  • Taylor D, Barnes T, Young A. Maudsley Prescribing Guidelines in Psychiatry, 13th edition. Oxford: John Wiley & Sons, May 2018. ISBN: 978-1-119-44260-8
  • Royal Pharmaceutical Society. Medicines Ethics and Practice (42nd edition). London: RPS, 2018. Standards for pharmacists to work to. It is not a free publication
  • World Anti Doping Agency WADA Prohibited List https://www.wada-ama.org/en/resources/science-medicine/prohibited-list-documents
  • Choiceandmedication; an independent source of information on many mental health conditions and their medicines with easy to read fact sheets www.choiceandmedication.org Personal subscriptions to download the app available for £1 per month (with proportionate discounts for longer periods) but your local mental health Trust may subscribe and provide information sheets for free.
  • Best Use of Medicines in Pregnancy (BUMPS). Information sheets on drugs in pregnancy http://www.medicinesinpregnancy.org/
  • Drugs and Lactation Database (LactMed). Information on drugs in breastfeeding https://toxnet.nlm.nih.gov/newtoxnet/lactmed.htm 
  • NICE Guidelines: Depression in children and young people: identification and management (CG28) last updated September 2017 available at https://www.nice.org.uk/guidance/cg28 Depression in adults: recognition and management (CG90) last updated April 2018 available at https://www.nice.org.uk/guidance/cg90