Hallucinations happen when someone sees, hears, smells, tastes or feels things that don't exist outside their mind. They're common in people with schizophrenia and are usually experienced as hearing voices.
Hallucinations can be frightening as they may be unexpected and unwanted, but there's usually an identifiable cause. They can occur as a result of taking illicit drugs or alcohol, or as part of a mental illness such as schizophrenia.
Some people may experience hallucinations that aren't related to a mental illness.
If you have hallucinations and are worried about them, see your doctor straight away. If necessary, call for an ambulance as you may have a serious mental health condition.
Hallucinations can make you feel nervous, paranoid and frightened, and it's important to be with someone you can trust.
In the meantime, the following information explains the typical types of hallucinations, including why they occur and what you can do. It covers:
- hearing voices
- drug-induced hallucinations
- hallucinations and sleep
- hallucinations experienced by children with a fever
Hallucinations can also occur as a result of extreme tiredness or recent bereavement. However, these and other rarer causes are not covered here.
Hearing voices in the mind is the most common type of hallucination in people with conditions such as schizophrenia. The voices can be critical, complementary or neutral, and may give out potentially harmful commands or even engage the person in conversation. They may make a running commentary on the person's actions.
The experience is usually very distressing, but it's not always negative. Some people who hear voices are able to live with them and get used to them or may consider them a part of their life.
It's not uncommon for recently bereaved people to hear voices, and this may sometimes be the voice of their loved one.
If you're hearing voices, discuss any concerns you have with your doctor. They'll refer you to a psychiatrist if necessary. This is important in determining whether you have a serious mental illness.
There's no shame in seeing a psychiatrist, and it's important to be thoroughly assessed and treated early. If the voices you're hearing are due to schizophrenia, the earlier your treatment is started, the better the outcome.
You may also find the following advice helpful:
- talk to other voice hearers
- be open to discussing your voices
- try to understand where the voices come from and why, and what triggers them
Illegal drugs and alcohol
People can experience hallucinations when they're high on illicit drugs such as amphetamines, cocaine, LSD or ecstasy. Hallucinations can also happen during withdrawal from alcohol or drugs if you suddenly stop taking them.
Drug-induced hallucinations are usually visual but may affect other senses. Hallucinations include flashes of light or abstract shapes, or may even take the form of an animal or person. More often, visual distortions occur that alter the person's perception of the world around them.
These hallucinations can happen on their own or they can occur as a part of drug-induced psychosis. After long-term use, they may cause schizophrenia.
Some people take cannabis to "calm themselves" and relieve their psychotic symptoms, without realising that in the longer term, cannabis makes the psychosis worse.
Heavy use of alcohol can also lead to psychotic states, hallucinations and dementia.
Various prescription medicines can occasionally cause hallucinations. Elderly people may be at particular risk.
Hallucinations caused by medications can be dose-related and usually go away when you stop taking the medicine. However, never stop taking medication without speaking to a doctor first, and if necessary after being assessed by a psychiatrist.
Speak to a doctor about how the medication is affecting you, so you can discuss the possibility of switching to another medicine.
Hallucinations and sleep
It's relatively common for people to have hallucinations just as they're falling asleep (hypnagogic), or as they start to wake from sleep (hypnopompic).
You may hallucinate sounds or see things that don't exist, such as moving objects or even a formed image such as a person (people may think they've seen a ghost).
Hypnagogic and hypnopompic hallucinations are especially common in people with the sleep disorder narcolepsy, although they're also common in people without this or any disorder. They're essentially like dreams, and in themselves are nothing to worry about.
Hallucinations in children with a fever
Hallucinations can sometimes occur in children who are ill with a fever. If your child is unwell with a body temperature of over 37.5C (99.5F) and you think they're hallucinating, call a doctor.
In the meantime, stay calm, keep your child cool and reassure them. Encourage them to drink plenty of fluids and give them paracetamol or ibuprofen (always read the patient information leaflet to find out the correct dose and frequency for your child’s age, and check they're not allergic to medicines you give them). The hallucinations should pass after a few minutes.
For more information, read about fever in children.