Antidepressants are drugs that relieve the symptoms of depression. They were first developed in the 1950s and have been used regularly since then. There are almost thirty different kinds of antidepressants available today and there are five main types:

We don't know for certain, but we think that antidepressants work by increasing the activity of certain chemicals work in our brains called neurotransmitters. They pass signals from one brain cell to another. The chemicals most involved in depression are thought to be Serotonin and Noradrenaline.

After 3 months of treatment, the proportions of people with depression who will be much improved are:

It may seem surprising that people given placebo tablets improve, but this happens with all tablets that affect how we feel - the effect is similar with painkillers. Antidepressants are helpful but, like many other medicines, some of the benefit is due to the placebo effect.

Yes and no. The older tablets (Tricyclics) are just as effective as the newer ones (SSRIs) but, on the whole, the newer ones seem to have fewer side-effects. A major advantage for the newer tablets is that they are not so dangerous if someone takes an overdose.

At the end of the leaflet you can find a list of antidepressants, their trade names, and their type.

Yes - your doctor will be able to advise you here. You should always remind him or her of any medical conditions you have or have had in the past. Listed below are the side effects you might experience with the different types of antidepressant:

Tricyclics

These commonly cause a dry mouth, a slight tremor, fast heartbeat, constipation, sleepiness, and weight gain. Particularly in older people, they may cause confusion, slowness in starting and stopping when passing water, faintness through low blood pressure, and falls. If you have heart trouble, it may be best not to take one of this group of antidepressants. Men may experience difficulty in getting or keeping an erection, or delayed ejaculation. Tricyclic antidepressants are dangerous in overdose.

SSRIs

During the first couple of weeks of taking them, you may feel sick and more anxious. Some of these tablets can produce nasty indigestion, but you can usually stop this by taking them with food. More seriously, they may interfere with your sexual function. There have been reports of episodes of aggression, although these are rare.

The list of side-effects looks worrying - there is even more information about these on the leaflets that come with the medication. However, most people get a small number of mild side-effects (if any). The side-effects usually wear off over a couple of weeks as your body gets used to the medication. It is important to have this whole list, though, so you can recognise side-effects if they happen. You can then talk them over with your doctor.

The more serious ones - problems with urinating, difficulty in remembering, falls, confusion - are uncommon in healthy, younger or middle-aged people. It is common, if you are depressed, to think of harming or killing yourself. Tell your doctor - suicidal thoughts will pass once the depression starts to lift.

SNRIs

The side-effects are very similar to the SSRIs, although Venlafaxine should not be used if you have a serious heart problem. It can also increase blood pressure, so this may need to be monitored.

MAOIs

This type of antidepressant is rarely prescribed these days. MAOIs can give you a dangerously high blood pressure if you eat foods containing a substance called Tyramine. If you agree to take an MAOI antidepressant your doctor will give you a list of foods to avoid.

NASSAs

The side-effects are very similar to SSRIs. It can make you feel drowsy, encourages weight gain, but it causes less sexual problems.

Some antidepressants make you sleepy and slow down your reactions - the older ones are more likely to do this. Some can be taken if you are driving. Remember, depression itself will interfere with your concentration and make it more likely that you will have an accident. If in doubt, check with your doctor.

Antidepressant drugs don't cause the addictions that you get with tranquillisers, alcohol or nicotine, in the sense that:

However, up to a third of people who stop SSRIs and SNRIs have withdrawal symptoms which can last between 2 weeks and 2 months.

These include:

Some people have reported that, after taking an SSRI for several months, they have had difficulty managing once the drug has been stopped and so feel they are addicted to it. Most doctors would say that it is more likely that the original condition has returned.

The Committee of Safety of Medicines in the UK reviewed the evidence in 2004 and concluded 'There is no clear evidence that the SSRIs and related antidepressants have a significant dependence liability or show development of a dependence syndrome according to internationally accepted criteria.'

There is some evidence of increased suicidal thoughts (although not actual suicidal acts) and other side-effects in young people taking antidepressants. So, SSRI antidepressants are not licensed for use in people under 18. However, the National Institute for Clinical excellence has stated that Fluoxetine, an SSRI antidepressant, can be used in the under-18s.

There is no clear evidence of an increased risk of self-harm and suicidal thoughts in adults of 18 years or over. But, individuals mature at different rates. Young adults are more likely to commit suicide than older adults, so a young adult should be particularly closely monitored if he or she takes an SSRI antidepressant.

It is always best to take as little medication as possible while you are pregnant. However, if you are one of those people who may need medication to stay well, it's best to discuss the benefits and risks with your doctor. There are a number of issues to consider. For example, you will need to think about:

Antidepressants don't necessarily treat the cause of the depression or take it away completely. Without any treatment, most depressions will get better after about 8 months.

If you stop the medication before 8 or 9 months is up, the symptoms of depression are more likely to come back. The current recommendation is that it is best to take antidepressants for at least six months after you start to feel better. It is worthwhile thinking about what might have made you vulnerable, or might have helped to trigger off your depression. There may be ways of making this less likely to happen again.

If you have had two or more attacks of depression then treatment should be continued for at least two years.

Some people have severe depressions over and over again. Even when they have got better, they may need to take antidepressants for several years to stop their depression coming back. This is particularly important in older people, who are more likely to have several periods of depression. For some people, other drugs such as Lithium may be recommended.Psychotherapy may be helpful in addition to the tablets.

It's difficult to say - so much depends on why they have been prescribed, on how bad your depression is and how long you've had it for. It's generally accepted that most depressions resolve themselves naturally within about 8 months. If your depression is mild it is best to try some of the other treatments mentioned later in this leaflet. If you can’t decide, talk it over with your doctor.

It is not enough just to take the pills. It is important to find ways of making yourself feel better, so you are less likely to become depressed again. These can include finding someone you can talk to, taking regular exercise, drinking less alcohol, eating well, using self-help techniques to help you relax and finding ways to solve the problems that have brought the depression on. For some tips on self-help, see our leaflet on depression.

Talking treatments

There are a number of effective talking treatments for depression. Counselling is useful in mild depression. Problem solving techniques can help where the depression has been caused by difficulties in life. Cognitive Behavioural Therapy was developed to treat depression and helps you to look at the way you think about yourself, the world and other people. For information about these and other forms of psychotherapy, see our leaflets on Psychotherapy and Cognitive Behavioural Therapy.

Herbal remedies

There is also a herbal remedy for depression called Hypericum. This is made from a herb, St Johns Wort, and is available without prescription. It seems to work in much the same way as some antidepressants, but some people find that it has fewer side-effects.  One problem is that it can interfere with the way other medications work. If you are taking other medication, you should discuss it with your doctor.

Light

You may find that you get depressed every winter but cheer up when the days become sunnier. This is called seasonal affective disorder (SAD). If so, you may find a light box helpful - this is a source of bright light which you have on for a certain time each day and which can make up for the lack of light in the winter.

Recent studies have suggested that over a period of a year, many of these psychotherapies are as effective as antidepressants. It is generally accepted that antidepressants work faster (see references). Some studies suggest that it is best to combine antidepressants and psychotherapy. Unfortunately some of these therapies are not readily available within the NHS in some parts of the country.

Hypericum, or St John's Wort, is widely used as an antidepressant in Germany. It seems to be as effective as antidepressants in milder depression, although there is little published evidence for its effectiveness in moderate to severe depressions.

Exercise and self-help books based on Cognitive Behavioral Therapy can be effective treatments for depression. If you have any further questions about antidepressants which haven't been covered in this leaflet, take a look at the further reading section and have a word with your doctor or psychiatrist. It's also good to talk things over with your family or friends.