Substance-induced psychosis: symptoms, causes and treatment

Psychosis is a set of symptoms rather than a single illness. The NHS describes it as people losing some contact with reality, which might involve seeing or hearing things that other people cannot see or hear (hallucinations) and believing things that are not actually true (delusions), along with confused thinking and speech. Experiencing these symptoms is often called having a psychotic episode.

When the episode is brought on by alcohol or drugs, or by stopping them, it is usually described as substance-induced psychosis. The NHS identifies psychosis as something that can be caused by a mental health condition, a general medical condition, or alcohol or drug misuse, and says it is sometimes possible to identify the cause as a specific condition such as schizophrenia, bipolar disorder or severe depression. Working out which applies is a main aim of the assessment.

The NHS lists three main symptoms of psychosis, and the combination of hallucinations and delusional thinking can cause severe distress and a change in behaviour.

• Hallucinations: hearing, seeing and sometimes feeling, smelling or tasting things that do not exist outside the mind but can feel very real. Hearing voices is a common example.

• Delusions: strong beliefs that are not shared by others, such as believing there is a conspiracy to harm you.

• Disordered thinking and speaking: thoughts and ideas come very quickly, which can make speech fast and confusing.

The NHS says alcohol-use disorder and drug misuse can trigger psychosis. A psychotic episode can occur after drinking large amounts of alcohol or while high, and also in withdrawal when someone suddenly stops after prolonged use.

Drugs the NHS lists as known to trigger psychotic episodes are cocaine, amphetamine (speed), methamphetamine (crystal meth), mephedrone, MDMA (ecstasy), cannabis, LSD (acid), psilocybins (magic mushrooms) and ketamine. It also lists prescribed medicines, which in rare situations can cause psychosis as a side effect or through overdose.

Other triggers the NHS lists for psychosis in general include a traumatic experience, stress, lack of sleep, physical conditions such as a brain tumour or dementia, head injury and childbirth. These can sit alongside substance use, which is another reason the cause is not always obvious at first.

The NHS adds that people with a history of psychosis are more likely than others to have drug or alcohol misuse problems, and that some use these substances to manage psychotic symptoms. Alcohol or drug use can make psychotic symptoms worse or cause other problems.

The NHS says there is no test to positively diagnose psychosis. A GP will ask about your symptoms and possible causes, including whether you are taking any medicines, your use of alcohol or drugs, your mood, how you are functioning day to day, whether there is a family history of mental health conditions such as schizophrenia, the details of any hallucinations and delusions, and whether you have harmed yourself or thought about it.

Because early treatment is more effective, the NHS says you are likely to be referred urgently to a specialist. Depending on the area this could be a community mental health team, a crisis resolution team or an early intervention team, which works with people who have had a first episode of psychosis. A psychiatrist will carry out a full assessment to identify any underlying mental health condition.

Honest information about what has been taken, and when, helps clinicians separate a substance-induced episode from an underlying illness, so it is worth giving details even if it feels difficult. People are not always able to recognise their symptoms, which is why the NHS notes that others may need to help them get support.

The NHS says treatment for psychosis depends on the cause but usually involves a combination of antipsychotic medicine to help relieve symptoms, talking therapies such as cognitive behavioural therapy (CBT) and family interventions, and social support with needs such as education, employment or accommodation. Some people are recommended to take antipsychotics on a long-term basis, while others may be able to gradually reduce the dose and stop if symptoms improve markedly. It says not to stop prescribed medicines suddenly as this could trigger a relapse.

If psychotic episodes are severe, a person may need to be admitted to a psychiatric hospital. The NHS says someone with very severe psychosis can be compulsorily detained at hospital for assessment and treatment under the Mental Health Act (1983).

When substances are involved, support to cut down or stop is a central part of care alongside treating the psychosis itself. Local drug and alcohol services and GPs can arrange this, and NHS mental health services can work with them. Waiting times and the services available differ across the UK nations and between areas.

The NHS says how often a psychotic episode occurs and how long it lasts can depend on the underlying cause. For some people, symptoms settle once the substance has left the body and the person is well supported. For others, an episode is the first sign of a longer-term condition, which is why follow-up matters even after the immediate crisis passes.

People with psychosis have a higher than average risk of self-harm and suicide, according to the NHS. It advises seeing a GP if you are self-harming and says the Samaritans can be called free of charge on 116 123. If you are feeling suicidal you can go to your nearest A&E, contact NHS 111 or make an urgent appointment with a GP, psychiatrist or care team.

The NHS also offers annual physical health checks at the GP surgery to people with a severe mental illness.

See a GP immediately if you have symptoms of psychosis. The NHS says that if you are concerned about someone else you can contact a GP for them, or their mental health worker if they are already supported by a service. If their symptoms are severe enough to need urgent treatment and could place them at risk, you can take them to the nearest A&E if they agree, call their GP or out-of-hours GP, or call 999 and ask for an ambulance.

If someone is a danger to themselves or others, call 999. If they have a crisis team, you can contact that team, or call 111 if you do not have the details.