Drugs or alcohol can be harmful to the physical and mental health of any individual who uses them but the risks are greater for people who have experienced psychosis or who have a predisposition to developing the condition. Certain types of drugs are thought to either cause or trigger a particular type of psychosis, for example, some people who are using cannabis, cocaine or amphetamines have been known to develop drug-induced psychosis. The psychotic symptoms arising as a result of using these substances can diminish within time if the person stops using drugs. However, this is not always the case and in some situations the person may have ongoing mental health difficulties. Some people also experience symptoms of psychosis when withdrawing from drugs or alcohol or when they are under the influence of harmful substances.
Continuing to use drugs during a psychotic episode has negative consequences. The risks include more persistent psychotic symptoms and a slower less complete recovery. Substance misuse is a common problem in people experiencing a first episode of psychosis. One study suggests that people experiencing psychosis are 4.6 times more likely to have drug or alcohol problems than the general population and are also less likely to comply with treatment. An individual can also develop other mental health problems alongside psychosis such as depressed mood, anxiety and addiction. It can also cause conflicts with family and friends who may be trying to help.