This information is for people who have dementia, or their carers. It tells you about haloperidol (Haldol), a treatment sometimes used for dementia. It is based on the best and most up-to-date research.
Does it work?
Haloperidol may reduce aggression and agitation (getting upset easily) in people with Alzheimer's disease or vascular dementia. But it can cause serious and unpleasant side effects.
What is it?
Haloperidol is an antipsychotic drug. This group of drugs is normally used to treat people who have serious mental health problems, that make them feel disconnected from their surroundings.
You can take haloperidol as tablets, capsules, a liquid, or an injection. Its brand names include Haldol, Dozic, and Serenace.
How can it help?
Taking haloperidol may reduce aggression (lashing out, swearing, and shouting) and agitation (getting upset easily) in some people with dementia.
It seems to work as well as a drug called risperidone.   (Risperidone is no longer recommended as a treatment for dementia in older people.)
How does it work?
Haloperidol works by blocking the action of dopamine, a chemical in the brain that helps electrical signals travel between brain cells (a neurotransmitter).
Symptoms such as delusions, aggression, and violence may happen because there is too much dopamine in the brain. Lowering the amount of dopamine may help these symptoms.
Can it be harmful?
Antipsychotics can have dangerous side effects when they're used to treat older people with dementia. People taking these drugs run a higher risk of serious heart problems or a stroke. Antipsychotics can also cause unpleasant but less dangerous problems, like muscle twitches.
Doctors in the UK are advised not to prescribe antipsychotic drugs for people with dementia. 
One study looked at long-term use of antipsychotic drugs, including haloperidol, for people with dementia. It found people taking one of these drugs were much less likely to be alive 1, 2, or 3 years later, compared with people taking a dummy (placebo) drug. 
All antipsychotic drugs can increase the risk of a stroke when they're used to treat older people with dementia.  There's a lower risk with older antipsychotics, like haloperidol, than with the newer ones, which include olanzapine and risperidone.
Another study suggested that the antipsychotic drugs haloperidol (brand name Haldol), olanzapine (brand name Zyprexa), and risperidone (Risperdal) were linked to a rise in the chances of people with dementia dying shortly after starting to take them. Another antipsychotic drug, quetiapine (Seroquel), did not show this increased risk. 
If you're caring for someone with dementia and their doctor recommends an antipsychotic drug, ask about the risks, and what the benefits of treatment might be.
One study has found that haloperidol increases the risk of a dangerously fast heartbeat.  If this isn't treated, it can make the heart suddenly stop working. This is called sudden cardiac arrest.