This information is for people who have bipolar disorder. It tells you about lithium, a treatment used to prevent relapses of bipolar disorder. It is based on the best and most up-to-date research.
Does it work?
Yes. There's good evidence to show that lithium helps stop the symptoms of bipolar disorder coming back.
It's important to take the right dose. Too much lithium can be dangerous.
What is it?
If you have bipolar disorder, your mood may be normal for a while. But then your mania or bipolar depression starts up again. In other words, you have a relapse. Doctors prescribe treatments like lithium to stop you having a relapse. Doctors have used lithium since the 1960s to treat mania and to prevent mania. 
Lithium is called a mood stabiliser. This means it makes you less likely to have mood swings. It can be used to treat mania and to prevent mania, without causing you to get depression. For more, see Lithium to treat mania.
Taking lithium when you don't have symptoms (when your mood is normal) is sometimes called maintenance treatment.
Lithium comes as tablets or a liquid. The brand names include Camcolit, Liskonum, Priadel, and Li-Liquid. You take it once or twice a day with meals.  But it can take a few months for lithium to get to the right level in your body. 
Different people need different doses of lithium. Your doctor will work out the best dose for you. You might need to take higher doses when you are having a bout of mania than you do at other times.
Also, if you are taking lithium to prevent relapses, but your mania does come back, you will probably keep taking the lithium. But you may need to take other medicines as well to help get the relapse under control.
How can it help?
If you take lithium you are much less likely to have a relapse of symptoms of bipolar disorder.
Here is what one summary of the research (a systematic review) showed in people who were treated for two years. 
Lithium seems to work better at stopping you getting new symptoms of mania than at stopping you getting new symptoms of depression. 
Some studies have compared lithium with other drugs for preventing a relapse.     They found lithium works at least as well as valproate, carbamazepine, and lamotrigine.
If you spot the early signs of a relapse while taking lithium, your doctor may recommend that you start taking another drug too. For example, he or she may suggest that you start taking an antipsychotic drug or an antidepressant drug as well. The aim is to head off the relapse or make it milder.