This information is for people who have bipolar disorder. It tells you about haloperidol, a treatment used for mania. It is based on the best and most up-to-date research.
Does it work?
Probably. If you are very agitated and restless, haloperidol can calm you down. And it works quickly. But this drug can give you side effects.
What is it?
Haloperidol belongs to a group of drugs called antipsychotic drugs. They have a calming effect when you are agitated or have strange or distressing thoughts.
Doctors also use haloperidol to treat schizophrenia. If you have schizophrenia, you can lose touch with reality. You may get symptoms called delusions or hallucinations. These are also called psychotic symptoms. But antipsychotic drugs are also used to treat mania, even if you don't have psychotic symptoms.
There are two groups of antipsychotic drugs, older ones and newer ones. Haloperidol is an older one. The older ones have been used for many years. But they can give you side effects, such as stiffness and shaking of your muscles. 
Haloperidol comes as tablets or as an injection. The brand names include Haldol and Serenace. You need a prescription from your doctor for this medicine.
Doctors may use the injection if they think you need treatment but you are too manic to take tablets. You can't be given treatment against your will, except in special cases covered by the law. For more information, see The Mental Health Act.
Doctors usually prescribe haloperidol along with another drug for mania such as lithium or valproate. 
How can it help?
Taking haloperidol can help with some of the symptoms of mania. These include getting upset easily and being aggressive. Taking haloperidol may work well as a short-term treatment for a bad bout of mania.  But you might have lots of side effects.
One study found that taking haloperidol helped reduce the symptoms of mania more than taking a dummy treatment (a placebo).  But lots of people dropped out of this study before it finished. This may mean the results aren't reliable.
Studies also show that taking haloperidol helps your symptoms of mania just as well as the taking the drugs called valproate and olanzapine.  
How does it work?
Your brain has lots of nerve cells. They send messages to each other using chemicals. These chemicals are known as neurotransmitters. Antipsychotic drugs work on one called dopamine.
Dopamine makes certain parts of your brain more active. Doctors think that the agitated mood you get with mania may happen because dopamine makes your brain too active.
Antipsychotic drugs like haloperidol dampen the effect of dopamine. This makes you calmer.
Can it be harmful?
Yes. Haloperidol can cause side effects. If you take this drug, you may get: