How does Fluoxetine work?

Depression is thought to be linked to low levels of naturally-occurring chemical messengers in the brain. These messengers are called neuro-transmitters. They send electrical impulses between different parts of the brain. In depression, two neuro-transmitters are known to be particularly important. These are called serotonin (pronounced seer-o-tone-in) and noradrenaline (pronounced nor-ad-ren-a-linn). Serotonin is also sometimes called 5HT for short.

Some antidepressants work by increasing the levels of serotonin in the brain. This type of antidepressant is called a selective serotonin re-uptake inhibitor or SSRI for short. SSRI antidepressants are the ones that are most widely used in Britain.

Some antidepressants work by increasing the levels of noradrenaline in the brain. Some antidepressants work by increasing the levels of both noradrenaline and serotonin.
It doesn’t seem to matter which neuro-transmitter is increased, all antidepressants are about equally effective.

Fluoxetine is an SSRI antidepressant and increases the levels of serotonin in the brain.

How should treatment with Fluoxetine be started, and what is the usual dose?

The usual dose is 20mg a day, which is also the recommended starting dose. Depending on how well you respond, and what side effects you have experienced this can be increased by 20mg at a time to a maximum of 60mg/day.

It is a generally a good idea to leave enough time between dose increases to see whether the increased dose improves the response, or causes more side effects before increasing the dose again.

Fluoxetine can have an awakening effect – like drinking coffee, so it’s best taken in the morning.

Dose in the elderly
In the elderly, the recommended starting dose is 20mg a day, increasing to 40mg a day if needed depending on how well they respond, and whether there are any problems with side effects.

People with liver disease
If you have liver disease, a lower or less frequent dose (eg, 20mg every two days) should be considered

What type of medicine is Fluoxetine and what is it used for?

Fluoxetine is an antidepressant medicine. Its main use is to treat the symptoms of depression.

It can also help people with:

Brief description of depression

Depression is a condition that affects both your mental and your physical health. It can cause a persistently low mood, prevent you from enjoying your life, interfere with your sleep, make it very difficult to concentrate, sap your energy, affect your appetite and cause unpleasant morbid thoughts about death and suicide. Depression affects different people in different ways: some people may have many symptoms of depression, but are able to get on with their lives; others may have few symptoms but be completely unable to cope.

Treatments for depression

Most people with depression are not able to manage without outside help. Many people are not aware that help – and choices – are available at all. For some people with depression, talking treatments like cognitive behavioural therapy (called CBT for short) are effective. Other people respond better to antidepressant medicines. Some people need both. CBT works best in milder forms of depression, while in more severe forms of depression, antidepressants work better. The important thing to know is that the majority of people with depression can be treated successfully.

Antidepressant medicines

Antidepressants are not very effective in milder forms of depression, but may be of benefit if you are suffering with anxiety. They have been shown to be effective in moderate to severe depression, and, in severe depression, can be combined with CBT.

Taking an antidepressant is not a sign of weakness, but is a positive decision to take control of your depression.

Is there anything else I should know about Fluoxetine?

Yes. Fluoxetine is an SSRI antidepressant.

SSRI antidepressants – problems with agitation and anxiety

In the early stages of treatment, in a small proportion of people who take them, SSRI antidepressants can make you feel:

If you get these symptoms and find that they are distressing you should tell your GP immediately, especially if they are severe, came on abruptly, or were not among the symptoms you went to the doctor with originally.

Click here to learn more about antidepressant side effects

Shortly after you have started taking an SSRI antidepressant your doctor should check whether you are having these symptoms.

If you feel very restless and agitated over a long period of time your doctor should consider whether you need a change of medication.

SSRI antidepressants and the risk of stomach bleeds

When combined with some painkillers called non-steroidal anti-inflammatory drugs (NSAIDs for short) or aspirin, or medicines used to prevent strokes, SSRI antidepressants have been associated with an increased risk of bleeding in the stomach. It is recommended that if you are taking any of these medicines together with an SSRI antidepressant, you should receive additional medication to prevent possible stomach bleeds. If you are taking an SSRI antidepressant on its own, you won’t need this additional medication.

If you are taking any medicines, you should ask your pharmacist if any of them fall into these groups.

Some of these medicines can be bought without a prescription – so always ask your pharmacist for advice before buying any non-prescription treatments for minor ailments.

Rash and allergic reactions with Fluoxetine

Rash and sometimes serious allergic reactions have been reported during treatment with Fluoxetine. If you get a rash or have an allergic reaction while taking Fluoxetine you should stop taking it and see your doctor as soon as you can.