We asked Dr Philip Timms, honorary senior lecturer in psychiatry at King’s College London, what he would want to know if he was diagnosed with psychotic symptoms.

What things might suggest that my partner, friend or child is having psychotic experiences that could be part of a mental illness?

Hearing voices (auditory hallucinations) tends to start as a fleeting experience, which gradually becomes louder and more persistent. These hallucinations often seem like a conversation between other people who are saying cruel or unkind things. The person hearing voices may be upset. They may also feel embarrassed or worried about what others might think and avoid talking about what's happening.

Those vague feelings of discomfort can grow into delusions. They have misplaced and false ideas which often have an air of suspicion about them and make the person experiencing them feel left out, as if secret things only known to other people are going on.

Describing the voices and feelings is never easy and can get harder. As the problems develop, concentration may fade and thinking can seem fragmented. This ‘thought disorder’ expresses itself in ideas and phrases that don’t seem to join up.

How harmful is this experience when it happens?

With both hallucinations and delusions the most important issue is how they affect the individual’s frame of mind, their feelings and their sense of safety. Some people find these experiences troublesome, causing them genuine distress. Mistrust can extend to people who care about them and health professionals trying to help.

Do people ever get over it?

It seems likely that at least 20% of people going through this kind of experience, which in some cases lasts as long as 18 months, will never have such feelings or thoughts again. Some people can work and interact with friends and families without the voices or feelings dominating or damaging how they get on in the world. Others may need medication to help them stay in control. There is a wide range of medications available and individuals can respond quite differently to the same medication. It can be difficult to predict who will do well on which medication, or to know how long they should take it for. Talking treatments, such as cognitive behavioural therapy, can also be helpful.

So there’s more to a psychotic experience than just hearing voices or having strange ideas?

It might be best to describe a psychotic experience as a time in an individual’s life when they are overwhelmed by the frequency and strength of these distressing thoughts and feelings and find it hard to tell the difference between them and reality.

Are self-help groups useful?