They work by normalising the chemicals in the brain to lift your mood, however they may not provide a complete solution as they do not tackle the underlying cause of the depression. They also do not work for everyone.

How well do antidepressants work?

After 3 months of taking an antidepressant between 50 and 65 per cent of people with depression will be much improved.

Interestingly 25 to 30 per cent of people with depression who were given a dummy pill over the same period of time also reported significant improvements in their mood.

There are several types of antidepressant. The two most common are:

• tricyclics (such as Tofranil and Lentizol)
• SSRIs, which stands for selective serotonin re-uptake inhibitors and includes Prozac.

Antidepressants are only available on prescription, they can come as tablets, capsules and sometimes in a liquid form. All antidepressants take two to three weeks to start having any effect and it may take up to six weeks before they start working fully.

Unfortunately many of the side effects caused by these drugs tend to occur immediately, but they often disappear after a few weeks, although not everyone will have these side effects.

Older people are usually advised to take an antidepressant for 7 -12 months, although people with recurrent depression often take a maintenance dose of antidepressant for several years.