People can experience hallucinations when they're high on illegal drugs such as amphetamines, cocaine, LSD or ecstasy. They can also occur during withdrawal from alcohol or drugs if you suddenly stop taking them.
Drug-induced hallucinations are usually visual, but they may affect other senses. They can include flashes of light or abstract shapes, or they may take the form of an animal or person. More often, visual distortions occur that alter the person's perception of the world around them.
The hallucinations can occur on their own or as a part of drug-induced psychosis . After long-term drug use, they may cause schizophrenia.
Some people take cannabis to "calm themselves" and relieve their psychotic symptoms, without realising that in the longer term, the cannabis makes the psychosis worse.
Heavy alcohol use can also lead to psychotic states, hallucinations and dementia.
Find out how to get help for a drug problem .
Various prescription medicines can occasionally cause hallucinations. Elderly people may be at particular risk.
Hallucinations caused by medication can be dose-related and they usually stop when you stop taking the medicine. However, never stop taking a medication without speaking to your doctor first and, if necessary, after being assessed by a psychiatrist.
Speak to your GP about how the medication is affecting you, so you can discuss the possibility of switching to another medicine.
Read about hallucinations, including the possible causes and practical advice about what to do if you experience them.
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