One of the most important aspects of taking antidepressants is when and how to eventually come off them. Dr Lesley Hickin investigates

Deciding when and how to stop taking your antidepressant medication is an important step. You should always discuss this with your doctor and together decide whether it is the right time to stop. It is also important to keep in touch with your doctor during the time while you are coming off your medication to deal with problems that arise.

Usually these drugs should be slowly reduced in dose, since all antidepressants have the potential to cause withdrawal reactions. This is not a new finding, and has been recognised since these drugs were first introduced. Many doctors remain unaware of these and much more research is necessary into the causes.

If you have been on an antidepressant continually for six weeks or more (some writers on the subject say more than four weeks), you should not stop treatment abruptly unless there are special circumstances. The exception to this is fluoxetine at 20mg a day, because it remains in the bloodstream for such a long time anyway it performs its own gradual reduction in blood levels. If you prefer (and this is what the advice is in the pack information leaflet), the best thing to do with fluoxetine is to gradually space out the doses from once daily to once every two days and so on. With antidepressants that have a shorter time in your bloodstream (doctors call it the half-life of a drug), the best thing is to reduce the daily dose every one to two weeks.

Withdrawal symptoms
Antidepressants are not usually thought of as drugs of addiction in the way that cocaine, heroin, morphine and nicotine can be. When you stop taking antidepressants you will not suffer from 'cold turkey' in the way that opiate addicts do. However, it is common to get some symptoms if you stop an antidepressant abruptly, and these withdrawal symptoms are known as antidepressant discontinuation syndrome.

Withdrawal symptoms after stopping tricyclic antidepressants such as amitriptyline, nortriptyline and dothiepin can appear within a few days of stopping the drug. Sickness and diarrhoea, flu-like symptoms, tiredness, anxiety and nightmares and disturbed sleep are all quite common.

With SSRIs such as fluoxetine, paroxetine, citalopram, sertraline and fluvoxamine, symptoms begin after one to three days and usually last one to two weeks, although some reports indicate that they can go on for longer. The most common problems are dizziness, nausea, tiredness and headache. Other symptoms can include feeling anxious or feelings similar to small electric shocks. These can be very distressing and there are many reports of them.

Work with your doctor
It is very important as you stop or reduce the dose of your antidepressants to keep your doctor informed about your progress. For many people, the withdrawal symptoms are mild and short-lived. For others, symptoms can be unpleasant and severe, and make it difficult to come off their medication. Sometimes the symptoms are confused with a return of depression. If you start to feel depressed again this will be unlikely to occur quickly after stopping the drugs, but may appear gradually over the next few months.

Stopping treatment gradually rather than suddenly will make withdrawal symptoms much less likely, although some people report problems even with a very slow reduction in dose. Working out a plan with your doctor for slowly reducing the dose of your antidepressant can help avoid a discontinuation reaction. After six to eight months' treatment the dose should normally be reduced over six to eight weeks, and more slowly still if you have been treated for longer. If you get a recurrence of depressive symptoms or severe discontinuation symptoms, it may be better to go back to a higher dose and withdraw more slowly. Any discontinuation symptoms should disappear within 24 hours of restarting the drug.

Switching drugsIf you are stopping one antidepressant and changing to a different one (this is usually because of the drug not working or giving you intolerable side effects), then the one you are stopping should usually be gradually tapered down in dosage while the new drug is being introduced. In the case of some drugs the two should not be taken at the same time and there is a gap of one to two weeks before the new drug is introduced. The combination could give you extra side effects called the serotonin syndrome in which you may experience restlessness, sweating, tremor, shivering, muscle twitching, confusion or convulsions.