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Olena, Prozac, Prozep

Try to take fluoxetine at the same time each day.

It may take up to four weeks after starting this treatment before you feel the full benefit. Do not stop taking it, feeling it is not helping.

Tell your doctor if you feel that you are not getting any better, or if you experience any troublesome side-effects.

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About fluoxetine

Type of medicine

A selective serotonin reuptake inhibitor (SSRI) antidepressant

Used for

Depression, bulimia nervosa, and obsessive-compulsive disorder (OCD)

Also called

Olena®; Prozac®; Prozep®

Available as

Capsules, soluble (dispersible) tablets and oral liquid medicine

Fluoxetine is prescribed for depression, bulimia nervosa, and obsessive-compulsive disorder (OCD). Depression can develop for no apparent reason, or it can be triggered by a life event such as a relationship problem, a bereavement, or an illness. Bulimia nervosa is an eating disorder. People with bulimia nervosa have episodes of binge eating which they counteract by making themselves sick. Obsessive-compulsive disorder (OCD) is a condition where you have recurring and persistent ideas that make you do repetitive actions.

Brain cells, called neurons, release a number of chemicals which go on to stimulate other neurons. This leads to electrical impulses which result in many functions controlled by the brain. Serotonin is one such chemical in the brain. Once released, it stimulates other neurons and is then taken back up into the neuron cells and recycled. Selective serotonin reuptake inhibitors (SSRIs) like fluoxetine increase the amount of circulating serotonin available in your brain. Altering the balance of the chemicals in the brain can help the symptoms of depression, eating disorders like bulimia, and OCD.

Before taking fluoxetine

Some medicines are not suitable for people with certain conditions, and sometimes a medicine may only be used if extra care is taken. For these reasons, before you start taking fluoxetine it is important that your doctor knows:

  • If you are pregnant, trying for a baby or breastfeeding.

  • If you have any problems with the way your liver works.

  • If you have a heart condition.

  • If you have epilepsy.

  • If you have high blood sugar levels (diabetes mellitus).

  • If you have an eye problem called glaucoma.

  • If you have ever had a bleeding disorder.

  • If you have ever had abnormally 'high' moods, called mania.

  • If you are being treated with electroconvulsive therapy (ECT).

  • If you have ever had an allergic reaction to a medicine.

  • If you have taken an antidepressant known as a monoamine-oxidase inhibitor (MAOI) within the previous two weeks.

  • If you are taking any other medicines. This includes any medicines you are taking which are available to buy without a prescription, as well as herbal and complementary medicines.

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How to take fluoxetine

  • Before you start the treatment, read the manufacturer's printed information leaflet from inside the pack. It will give you more information about fluoxetine and will provide you with a full list of the side-effects which you may experience from taking it.

  • Take fluoxetine exactly as your doctor tells you to - the directions will be printed on the label of the pack to remind you of what your doctor said. As a guide, if you are being treated for depression or OCD, it is usual to be prescribed 20 mg (one capsule or 5 ml liquid medicine) as a once-daily dose. Your dose may later be increased. For people being treated for bulimia, the usual daily dose is 60 mg (three capsules or 15 ml liquid medicine). You can generally take fluoxetine at a time to suit you, but try to take your doses at the same time of day, each day.

  • You can take fluoxetine before or after food. If you have been given capsules, swallow them whole with a drink of water - do not chew or open the capsules. If you have difficulty swallowing capsules, let your doctor know, as you could be prescribed liquid medicine or soluble tablets to take instead.

  • If you have been given soluble (dispersible) tablets, they can be swallowed whole with a drink of water or dissolved in half a glass of water before taking. Do not crush or chew the tablets.

  • If you forget to take a dose, take it as soon as you remember. If you do not remember until the following day, skip the missed dose. Do not take two doses together to make up for a forgotten dose.

Getting the most from your treatment

  • You may feel that fluoxetine is not working for you straightaway. It can take a week or two after starting this treatment before the effect begins to build up, and 4-6 weeks before you feel the full benefit. Do not stop taking it after a week or two, feeling it is not helping.

  • Try to keep your regular appointments with your doctor. This is so your doctor can check on your progress.

  • While you are taking fluoxetine, you may have thoughts about harming yourself or ending your life. These thoughts may also be associated with your condition. It is very important that you tell your doctor about this if it happens.

  • Do not stop taking fluoxetine unless your doctor tells you to do so. Stopping treatment suddenly can cause problems and your doctor will probably want you to reduce your dose gradually when this becomes necessary. You should expect that a course of treatment will last for several months. This is normal and helps to prevent your symptoms from recurring.

  • If you drink alcohol, ask your doctor for advice. Your doctor is likely to recommend that you do not drink alcohol while you are on fluoxetine.

  • If you have diabetes, you may need to check your blood glucose more frequently, as fluoxetine may affect the levels of sugar in your blood. Your doctor will be able to advise you about this.

  • If you buy any medicines, check with a pharmacist that they are safe to take with fluoxetine. This is because several medicines which are available from general retail outlets can interfere with this treatment. In particular, do not take the herbal remedy St John's wort, and ask for advice before buying any anti-inflammatory painkillers.

  • A few people taking fluoxetine find that their skin is more sensitive to sunlight than normal. Until you know how your skin reacts, use a sun cream with a high sun protection factor (SPF) in strong sunlight.

  • There are several types of antidepressants and they differ in their possible side-effects. If you find that fluoxetine does not suit you then let your doctor know, as another may be found that will.

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Can fluoxetine cause problems?

Along with their useful effects, most medicines can cause unwanted side-effects although not everyone experiences them. The table below contains some of the most common ones associated with fluoxetine. You will find a full list in the manufacturer's information leaflet supplied with your medicine. The unwanted effects often improve as your body adjusts to the new medicine, but speak with your doctor or pharmacist if any of the following continue or become troublesome.

Common fluoxetine side-effects

What can I do if I experience this?

Feeling sick (nausea) or being sick (vomiting), indigestion, diarrhoea

Stick to simple foods

Dry mouth

Try chewing sugar-free gum or sucking sugar-free sweets


Drink plenty of water and ask your pharmacist to recommend a suitable painkiller. If the headaches continue, let your doctor know

Mood changes such as feeling anxious, nervous, agitated or forgetful. Feeling restless or shaky

These usually settle within a few days. If any become troublesome or severe, speak with your doctor

Feeling dizzy, tired or weak. Blurred vision

If this happens, do not drive and do not use tools or machines until you feel better

Flushing, sweating, difficulty sleeping, lack of appetite, loss of weight, aches and pains, reduced sexual drive or ability, yawning, a feeling that your heart is pounding (palpitations), itching, changes in taste

If any of these become troublesome, speak with your doctor

Important: a few people taking fluoxetine have developed an allergic-type reaction. You should contact your doctor straightaway if you develop any swelling around your face, any difficulties breathing, or a severe rash.

On rare occasions, medicines that affect the level of serotonin in the brain can cause it to go too high and cause problems. The risk is higher if you are taking more than one medicine with this effect. Seek medical attention if you develop any combination of the following:

  • Stiff muscles or 'jerky' movements.

  • Unusually fast heartbeat.

  • High temperature (fever), feeling sick (nausea) or being sick (vomiting), diarrhoea.

  • Feeling delirious or seeing visions (hallucinating).

If you experience any other symptoms that you think may be due to this medicine, speak with your doctor or pharmacist for further advice.

How to store fluoxetine

  • Keep all medicines out of the reach and sight of children.

  • Store in a cool, dry place, away from direct heat and light.

  • The oral liquid medicine usually lasts for one month after first opening. After this time make sure you have a fresh supply.

Important information about all medicines

Important information about all medicines

Never take more than the prescribed dose. If you suspect that you or someone else might have taken an overdose of this medicine, go to the accident and emergency department of your local hospital. Take the container with you, even if it is empty.

This medicine is for you. Never give it to other people even if their condition appears to be the same as yours.

If you are having an operation or any dental treatment, tell the person carrying out the treatment which medicines you are taking.

Do not keep out-of-date or unwanted medicines. Take them to your local pharmacy which will dispose of them for you.

If you have any questions about this medicine ask your pharmacist.

Report side effects to a medicine or vaccine

If you experience side effects, you can report them online through the Yellow Card website.

Further reading and references

Article history

The information on this page is written and peer reviewed by qualified clinicians.

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