Causes - Psychosis

Psychosis can be caused by a:

• psychological or mental health difficulty
• health condition
• substance such as alcohol or drugs

Psychological causes of psychosis

Psychosis can sometimes be part of a specific mental health difficulty such as:

• schizophrenia
• bipolar disorder
• severe depression

The type of mental health difficulty can affect:

• the type of psychotic episode that happens
• how often episodes happen

Schizophrenia

Schizophrenia causes a range of psychological symptoms.

These include:

• hallucinations - where a person sees, hears, smells, tastes or feels things that do not exist
• delusions - where a person has strong beliefs that are not shared by others, for example they believe there's a conspiracy to harm them
• disordered thinking and speaking - where a person's thoughts and ideas come quickly, making their speech fast and confusing

Schizophrenia

Bipolar disorder

This is a mental health difficulty that affects mood. If you have bipolar disorder, you can have episodes of low mood (depression) and high or elated mood (mania).

Bipolar disorder

Severe depression

Some people with depression also have symptoms of psychosis when they're very depressed.

This can be feelings of sadness that do not go away, for example postnatal depression.

Psychotic depression

Other causes

Psychosis can also be a result of:

• a traumatic experience
• stress
• drug misuse
• alcohol misuse
• side effects of prescribed medicines
• a health condition
• lack of sleep

Health conditions

These health conditions can trigger psychotic episodes in some people:

• HIV and AIDS
• malaria
• syphilis
• Alzheimer's disease
• Parkinson's disease
• hypoglycaemia (low level of glucose in the blood)
• lupus
• multiple sclerosis
• brain tumour

Substances

Alcohol misuse and drug misuse can trigger a psychotic episode.

Drugs known to trigger psychotic episodes include:

• cocaine
• amphetamine (speed)
• methamphetamine (crystal meth)
• mephedrone (MCAT or miaow)
• MDMA (ecstasy)
• cannabis (hash) or marijuana (weed)
• LSD (acid)
• psilocybins (magic mushrooms)
• ketamine

Psychosis can also happen during drug withdrawal. This is when you suddenly stop taking substances after using them for a long time. The episodes can happen a few weeks after stopping.

Psychosis can also happen as a side effect of some types of medicine. It can also happen as a result of an overdose of that medicine. These are rare.