• Anxiety.
• Phobias.
• Bulimia (an eating disorder).
• Some physical conditions.

Antidepressants work by boosting or prolonging the activity of particular brain chemicals, such as noradrenaline and serotonin, which are thought to be involved with regulating mood.

Noradrenaline and serotonin are neurotransmitters. This means that they pass messages between nerve cells in your brain, and between nerves and other target organs in the rest of your body.

By causing a change to your brain chemistry, antidepressants may lift your mood. However, antidepressants don't work for everyone, and there is no scientific evidence that depression is caused by a chemical imbalance which is corrected by antidepressants.

There are several different types of antidepressants, which were developed at different times. They all tend to act on the same brain chemicals and cause similar effects, but the different types have different chemical structures, and may have different side effects.

The different types are:

• selective serotonin reuptake inhibitors (SSRIs)
• serotonin and noradrenaline reuptake inhibitors (SNRIs)
• tricyclics and tricyclic-related drugs
• monoamine oxidase inhibitors (MAOIs)
• other antidepressants