Mental illness: what it is, types, symptoms and where to get help in the UK

Mental illness, also called a mental health condition or mental disorder, is an illness that affects mood, thinking, behaviour or how you relate to other people. It ranges from short episodes of low mood or anxiety to long-term conditions such as bipolar disorder or schizophrenia. Everyone has mental health, and the NHS Every Mind Matters service says life is full of ups and downs for us all, so the question is whether feelings become persistent or disabling.

The Royal College of Psychiatrists, whose patient information is written by psychiatrists in collaboration with patients and carers, lists a wide range, from ADHD, anxiety and depression to eating disorders, personality disorder, psychosis and PTSD. The NHS says your mental health is as important as your physical health.

The NHS mental health conditions pages cover a long list. The table groups the main ones using the NHS and NHS inform listings.

The Mental Health Foundation, citing national surveys, says one in five adults in England have a common mental health condition, mainly anxiety and depression, and that mixed anxiety and depression is Britain's most common mental disorder, affecting 7.8% of people. It adds that 4 to 10% of people in England will experience depression in their lifetime.

Rethink Mental Illness describes lifetime risk as one in four, and says about one in 100 people will develop schizophrenia, usually emerging in young adulthood. These figures come from different surveys using different definitions, so treat them as a guide to the scale of the problem rather than an exact count.

Symptoms depend on the condition. The NHS feelings and symptoms pages cover feelings that are common with mental health problems: stress, anxiety, fear and panic, low mood and depression, loneliness, grief, anger, and hallucinations and hearing voices.

A single bad day is not a mental illness. It becomes a concern when feelings are persistent, disproportionate or stop you doing what you normally do. Rethink Mental Illness says that if your mood stays low for a long period or stops you doing everyday activities, this could be a sign of depression and you might need some help.

• Low mood, hopelessness or loss of interest that does not lift.

• Excessive worry, fear or panic attacks.

• Changes in sleep, appetite or energy.

• Mood swings from extreme highs to extreme lows (a feature of bipolar disorder, according to Rethink).

• Hearing voices or seeing things others do not.

• Thoughts of self-harm or suicide, which always need prompt help.

Diagnosis is made from a conversation about your symptoms, how long they have lasted and how they affect your life, usually starting with a GP. The NHS says you do not need a diagnosed mental health condition to refer yourself to talking therapies. For some conditions, the GP refers you to a specialist, such as a psychiatrist or community mental health team, for assessment.

The Royal College of Psychiatrists' information includes how physical illness and mental health affect each other, so a GP may ask about your physical health too.

The NHS says talking therapies (psychological therapies) can be used to treat many different mental health problems, by talking to a trained professional about your thoughts, feelings and behaviours. Sessions may be in person, by video or phone, or as an online course, one-to-one or in groups.

The NHS mental health treatments hub also covers medicines such as antidepressants. The right mix depends on the condition, how severe it is and what you prefer, and a GP or specialist will explain the options.

The NHS says a mental health emergency should be taken as seriously as a physical one. If you need urgent help, call 111 or use 111 online and choose the mental health option, or ask for an urgent GP appointment. 111 will tell you the right place to get help, and you may be able to speak to a trained mental health professional over the phone.

Call 999 or go to A&E if someone's life is at risk, for example they have seriously injured themselves or taken an overdose, or you do not feel you can keep yourself or someone else safe. In A&E staff should refer you to a liaison psychiatry service or local crisis resolution and home treatment team.

• Samaritans offers free listening support, open 24 hours.

• Shout offers a free 24-hour text line.

• Childline supports anyone under 19.

• If you are worried about someone else, the NHS says just listening and taking them seriously can help more than having answers.

Children and young people can have mental health conditions too. The NHS has separate advice on anxiety in children, depression in children and young people, bereavement and talking to your child about feelings. Services for under-18s are different from adult services, and the NHS says if you are under 18 you can find out about getting mental health support for children and young people.

Childline offers confidential support to under-19s. A GP can help a young person and their family find the right service.

On the NHS you can refer yourself to talking therapies for anxiety and depression if you are registered with a GP and aged 18 or over (16 or over in some areas), or see a GP who can refer you to specialist services. Other routes include employer schemes, university services and local charities, and the NHS notes the Hub of Hope can help you find local mental health charities.

You may also choose to pay for therapy privately. The NHS advises checking that a private therapist is registered with a professional organisation accredited by the Professional Standards Authority.