Fluoxetine

Fluoxetine should start helping with depression within one to two weeks. It may take four weeks or longer for you to get the full effect.

How people respond to treatment can vary. Sometimes improvement is slow, and you may not feel any different to start with. This can be hard when your mood is low, and if you experience any side effects form your medication you may think you feel worse and not better. If you can, give your medication a chance to work and continue to take it for at least three to four weeks to see if it makes a difference.

Your parents, friends and doctor may notice an improvement in you before you feel it yourself, so it’s a good idea to talk to them.

If you think your medicine has not made any difference to how you feel after three to four weeks, you should go back to your doctor. They might recommend a change in dose or a different medication. However, it can take longer to work for some people than for others, so they may suggest you wait six to eight weeks before deciding.

For anxiety or obsessive-compulsive disorder, it may take longer for the benefits to be noticed. It could take up to three months before you feel the full benefit.

For some people, anxiety symptoms briefly increase at the start of treatment, but the anxiety should decrease over time as you continue to take your medicine. To avoid or minimise this, your doctor will usually start treatment with a low dose and increase this after one to two weeks.

Fluoxetine can make you feel less hungry than normal, which might lead to weight loss.

It is not possible to predict how fluoxetine will affect each person before they start taking it. Talk to your doctor or pharmacist if you are concerned about your weight, or changes to your weight, while taking fluoxetine.

A common side effect of fluoxetine is a dry mouth. Over a long time, this can increase your risk of developing tooth decay or gum disease. Make sure you brush your teeth well and have regular dental check-ups. Speak to your dentist, doctor or pharmacist about things you can do to help.

You may want to let your family and friends know you are taking fluoxetine so they can support you and help you look out for side effects.

For guidance on this, check out our page on getting support with your medication.

You can feel drowsy in the first few days of taking fluoxetine. However, it should get better after the first week or two.

You may become more anxious, or it may make you irritable which may also affect your sleep. If you experience this, it should settle after a couple of weeks. If these symptoms are very bad, or they continue for more than a couple of weeks, discuss this with your doctor
Some people find that fluoxetine makes them feel more alert or causes insomnia (difficulty getting to sleep). If this happens, try taking fluoxetine first thing in the morning.

If you find that fluoxetine is still affecting your sleep (either making you feel very sleepy or disrupting your sleep), and you’ve been taking it for more than a month, discuss this with your doctor or pharmacist.

Alcohol

It may be possible to drink some alcohol while taking fluoxetine, but it is best to do so in moderation. Fluoxetine can sometimes cause drowsiness as a side effect, so it is possible that alcohol might make you feel more drowsy than usual.

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.

During the first few weeks of treatment, it might be best to stop drinking alcohol until you see how the medicine affects you.

Drinking alcohol every day or in large amounts can make your symptoms worse and may mean you won’t get the maximum benefit from your medication.

Street drugs

Cannabis can have unpredictable effects when taken with fluoxetine, so great care is needed.

Cannabis and other drugs may have their own side effects on your mental health, like anxiety or psychosis.

Methadone and fluoxetine together can seriously affect your heart. (In some situations, methadone may be prescribed by your doctor. Fluoxetine and methadone can be prescribed together- but your doctor would monitor this very carefully)

Fluoxetine has been shown to dampen down the 'high' of cocaine.

Taking fluoxetine with cocaine, ecstasy or amfetamines could bring on serotonin syndrome. You could get a high temperature/fever, agitation, confusion, trembling or weird muscle movements. You need to go to hospital if this happens. Tell the doctor everything that you have taken.

Fluoxetine can produce a false positive test for amfetamines and LSD on a urine drug screen. Talk to your doctor about this if it is a problem for you.

There are many other street drugs, but we don’t know what effect taking them with fluoxetine will have, so it’s best to be cautious. There is no regulation of street drugs or ‘legal highs’, so even if there are no known issues with the medication you take, the supply you receive might be mixed with other substances that could be dangerous.

Get more advice on drugs and alcohol.

Fluoxetine does not mix well with some other medicines, including herbal medicines. It may affect how they work or could cause more side effects.

Do not take fluoxetine if you take an antidepressant medicine called a monoamine oxidase inhibitor (MAOI), or if you have taken one in the last two weeks. MAOIs include moclobemide, isocarboxazid, phenelzine and tranylcypromine.

Before you start taking fluoxetine, tell your doctor if you are taking any other medications, including things you have bought from a pharmacy (or other shop) for common illnesses like colds and flu. This includes medications that you put on your skin.

Look at the leaflet inside your medicine box for more information about other medicines that can interact with fluoxetine. With some medicines your doctor may need to adjust the dose of your medicines if you take them together. Ask a doctor or pharmacist for more information if you have any questions.

There are multiple companies that manufacture fluoxetine and multiple forms available, including capsules, dispersible tablets, tablets and liquids. The non-active ingredients vary between products and manufacturers, so if you have any food allergies or intolerances, always let your pharmacist know.

The liquid medication includes a small amount of alcohol, but not enough to affect your blood alcohol level. The liquid medication may also contain sucrose. A sugar-free alternative is available.

If you need to avoid animal products such as gelatine, please note that this is used in the manufacturing process for fluoxetine capsules.
Further information about practical considerations for medicines if you need to avoid animal products can be found on the Vegan Society website.

Taking fluoxetine may affect your ability to do things like driving a car, riding a bike, or anything else that needs a lot of focus or balance. It can make you tremble, feel dizzy or restless when you first start taking the medication.

It is recommended that you stop driving or riding a bike for the first few days or weeks until you know how it affects you.

Most people drive as normal while taking fluoxetine. If you are worried about this or have any concerns you would like to discuss, speak to your doctor or pharmacist.

Pregnancy

If you become pregnant while you are on fluoxetine, you should carry on taking the medicine and make an appointment to see your doctor as soon as possible. They can discuss the benefits and risks of continuing fluoxetine and help you to make a decision that is best for you and your baby. They may refer you to a specialist perinatal mental health team to support you with this decision.

You can find out more information about taking fluoxetine during pregnancy at Bumps (Best Use of Medicines in Pregnancy).

Untreated depression or anxiety (or other mental illness) can also be harmful to you and your developing baby, so decisions about stopping or avoiding medication when you are pregnant need to be discussed carefully with your doctor. If you and your doctor agree that carrying on with fluoxetine has more benefits than risks, you should tell your midwife that you are continuing to take this at your next appointment.

Some research has reported that taking SSRI antidepressants during the month before delivery can result in a small increased risk of bleeding after you have given birth. It will be important for your doctor and midwife to know what medication you are taking so that appropriate monitoring and treatment is planned. If you are concerned about this discuss it with your doctor and midwife.

If you are planning to get pregnant, it is recommended that you take folic acid while you are trying for a baby and during pregnancy. It is safe to take this together with fluoxetine.

Post-natal

If fluoxetine is taken in the last five months of a pregnancy, studies have shown a small increased risk of persistent pulmonary hypertension of the new-born (PPHN). This occurs in the first 24 hours after birth and can make the baby breathe faster and look a bit blue in colour. PPHN affects around three in 1,000 babies born to mums who take SSRIs. This compares with a rate of two in 1,000 among babies born to mums who do not take SSRIs. More recent research has failed to reproduce this finding. If you are concerned about this, talk to your doctor and midwife. If this does occur, you will need help from your midwife, so it is important they are looking out for symptoms.

There are some other symptoms that can occur in new-born babies if fluoxetine is taken in the last three months of pregnancy, look out for these and get help if they happen:

• jerking or twitching of the muscles or shaking
• being jittery, irritable or constant crying
• being too hot or cold
• suckling/ feeding difficulties or being sick
• having stiff or floppy muscles, or overactive reflexes
• being very sleepy or finding it difficult to sleep

These are usually mild and go away in a few days without treatment.

Breastfeeding

Talk to your doctor, midwife or pharmacist if you want to breastfeed while taking fluoxetine.

Some 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. However, the level of fluoxetine detected in breast milk is still considered safe if you are taking fluoxetine and want to breastfeed.

If you breastfeed while taking fluoxetine, seek urgent medical advice if your baby becomes restless, very sleepy, or develops feeding problems.

If your baby was born early or has health problems, then breastfeeding while taking fluoxetine may not be recommended. Talk to your midwife and doctor about feeding options.

If your medication makes you sleepy, do not to sleep with your baby in the same bed, and be cautious when handling your baby (especially if waking during the night for feeds).

Sex

Fluoxetine can have side effects that might affect your sex life. These include:

• painful erections, problems with getting an erection (getting hard) and ejaculating (coming)
• bleeding from the vagina and difficulty reaching orgasm (coming) the same way as before or not being able to have an orgasm at all
• reduced genital sensation
• lower sex drive

Most side effects occur when you first start medication and improve over time. If they do not, and this is a problem for you, make an appointment to discuss this with your doctor.

Some other rare side effects include breast growth or milk flow from the breasts. These may affect your confidence and therefore your desire to have sex. Talk to your doctor if you get these symptoms.

There is some evidence to indicate that some side effects affecting your sex life might continue for several months or longer after you stop your medicine. This is sometimes referred to as PSSD (post SSRI sexual dysfunction). More research is needed to understand how frequently this might happen. Discuss this with your doctor or pharmacist is you are concerned.

Fluoxetine has been known to slow growth and delay puberty in a small number of children and young people. Your doctor should check your growth while you are taking it. If you are concerned about this, talk to your doctor or pharmacist about it.

Untreated depression or anxiety can have a negative effect on your sex life, so if fluoxetine helps you to recover, positive effects can include improving your desire, experience and enjoyment of sex as your mood lifts and you become interested in life and relationships again.

Fertility

There is no evidence to show that fluoxetine affects fertility.

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

Fluoxetine is not a banned substance in sport.

Most people play sports as normal while taking fluoxetine. Taking fluoxetine may affect your ability to do things like riding a bike, competitive gymnastics, or anything else that needs a lot of focus. Fluoxetine may make you feel very restless in the first few weeks so you may find it difficult to sit or stand still when you first start this medicine.

It might be best to stop sports for the first few days until you know how it affects you or the effects get better.

If you are worried that taking fluoxetine might make doing the sports you enjoy more difficult, discuss this with your doctor.

Ideally it is best not to take fluoxetine for the first time just before your exams. It is not possible to predict how the medication will make you feel, and if you do get any side effects, these are more likely to occur when you first start taking fluoxetine.

Taking fluoxetine may affect your ability to do things that need a lot of focus, it may also affect your sleep and make you feel more anxious or restless, which might interfere with your preparation for 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 and ability to study.

Most people take exams as normal while taking fluoxetine. If you are worried that taking fluoxetine might make studying for or taking your exams harder, discuss this with your doctor.