This information is for people who have bipolar disorder. It tells you about lithium, a treatment used for bipolar depression. It is based on the best and most up-to-date research.
Does it work?
We're not sure. There have not been any good studies on lithium as a treatment for bipolar depression.
Doctors often use lithium for other reasons in people with bipolar disorder. It's also used to treat mania and to prevent a relapse.
If you have bipolar disorder and you're taking lithium, your doctor may recommend that you keep taking it if you get depressed, to help stop your mania coming back.
What is it?
Lithium is a drug that works against mania. It is called a mood stabiliser. This means it makes you less likely to have mood swings.
Lithium is a type of metal. It can sometimes be found naturally in spring waters. Doctors have used it since the 1960s to treat mania and to prevent mania. 
You need a prescription from your doctor for lithium. The brand names include Camcolit, Liskonum, Priadel, and Li-Liquid.
Lithium comes as tablets or a 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 blood. 
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.
How can it help?
We are not sure if lithium can help with bipolar depression. We didn't find any good studies on this. 
How does it work?
We don't know how lithium might work in bipolar depression. Lithium affects the levels of certain chemicals in your brain. These chemicals are called neurotransmitters. They carry messages between the nerve cells in your brain. Some of these chemicals help regulate your mood.
Can it be harmful?
Yes. People taking lithium often get side effects. And taking too much can be dangerous.
If you take lithium, you may get these side effects:  
One summary of the research (a systematic review) showed more than 9 in 10 people taking lithium got some side effects.  But nearly 8 in 10 people taking a dummy treatment (a placebo) got some too. So, we don't know if all the side effects were because of lithium.
The summary also showed that lithium didn't cause any more side effects than carbamazepine or valproate.
It's very important to get your dose right. If you take even slightly too much lithium, you are much more likely to get side effects.  Too much lithium can harm your kidneys, heart, lungs, and nervous system. You can even die. So, if you take too much, get medical help straight away.