This information is for people who have bipolar disorder. It tells you about antidepressants, a treatment used for bipolar depression. It is based on the best and most up-to-date research.
Do they work?
Probably. There's some good evidence that these drugs work as a treatment for the depression you get with bipolar disorder (bipolar depression).
But you can get a serious side effect. Antidepressants can make your mood swing from low to very high, and set off a bout of mania.
What are they?
Antidepressants treat the symptoms of depression. Doctors use three main types of antidepressants to treat bipolar depression.
Selective serotonin reuptake inhibitors (SSRIs for short). Some examples of SSRIs are citalopram (brand name Cipramil), fluoxetine (Prozac), fluvoxamine (Faverin), paroxetine (Seroxat), and sertraline (Lustral).
Tricyclic antidepressants (TCAs). Some examples of TCAs are amitriptyline, doxepin (Sinepin), nortriptyline (Allegron), and trimipramine (Surmontil).
Monoamine oxidase inhibitors (MAOIs). Some examples of MAOIs are phenelzine (Nardil) and tranylcypromine. But this type of antidepressant isn't used much any more.
Other antidepressants include venlafaxine (Efexor) and reboxetine (Edronax).
Sometimes doctors also give antidepressants to stop the symptoms of bipolar disorder from coming back. For more, see Antidepressants to prevent a relapse.
How can they help?
Antidepressants can help with the symptoms of depression. But there has not been much research looking at how well they work for people with bipolar disorder.
There have been lots of studies on using antidepressants for people with depression who don't get bouts of mania. Doctors call this type of depression unipolar depression.
These studies show that between one half and two-thirds of people with this type of depression feel much better after treatment with antidepressants.      
The studies show that taking an antidepressant can help in different ways.
You feel less sad, hopeless, worried, or guilty.
You feel like eating again.
Your sex drive comes back.
You can concentrate better.
There have also been some studies on antidepressants for people with bipolar depression. One study showed that people taking antidepressants were much more likely to get better than people taking a dummy treatment (a placebo). 
The study also showed that the SSRI antidepressants were more likely to help than the TCAs. 
How do they work?
Your brain has lots of nerve cells. They send messages to each other using chemicals. These chemicals are known as neurotransmitters.
People who are depressed have lower levels of certain chemicals than people who are not depressed. For example, they may have lower levels of the ones called dopamine, serotonin, and noradrenaline.
Antidepressants boost your levels of serotonin and noradrenaline. This slowly changes how the nerve cells in your brain work. It can take several weeks before you can tell if the drugs are helping.