SSRIís (selective serotonin reuptake inhibitors) are usually the first choice of drugs used to treat depression. This family of anti-depressants is often effective and tends to have fewer side-effects. Common SSRI's include include sertraline, citalopram and fluoxetine.

Serotonin is a neurotransmitter made by the cells in the brain. Neurotransmitters are chemicals used by brain cells to connect and communicate with each other. SSRI antidepressants slow the rate that the brain breaks down serotonin. This in turn causes an increase in serotonin activity in the brain. This has been shown to improve symptoms of depression.

Common side effects include:

Mild nausea and vague headache which usually clear after a few days of use

Diarrhoea and abdominal cramping pain

Agitation and physical restlessness

Reduced sex drive and difficulty reaching an orgasm

The effect on weight is unclear, however appetite reduction and weight loss most likely with fluoxetine and weight gain is possible with some other SSRIs.

The effect on sleep is unpredictable, however broken sleep is common with some of the SSRI medications (Fluoxetine, Prozac/Lovan), while others may cause sleepiness (Fluvoxamine, Luvox).

SSRIs may lalso cause intensified dreaming.