Patients with the serious mental health condition bipolar disorder should get annual health checks, a watchdog has recommended.
Bipolar can trigger extreme symptoms
As many as one in 100 people have the condition, also known as manic depression.
But it is often not picked up - patients can wait an average of eight years to get a correct diagnosis.
The new guidelines are published by the National Institute for Health and Clinical Excellence (NICE).
Drawn up in collaboration with the National Collaborating Centre for Mental Health, they set out the criteria for when patients need to be referred on for specialist psychiatric assessment and treatment.
The guidelines also set out the drug treatment options for people with bipolar disorder, and call for healthcare professions to carefully monitor their patients' medication.
Mr Stephen Pilling, consultant clinical psychologist and joint director of the National Collaborating Centre for Mental Health, said people needed better and swifter treatment.
"It can take on average about eight years from onset of first symptoms to receiving a diagnosis of bipolar disorder. This is far too long.
"More needs to be done to improve awareness, identification and recognition of the problem, which can be misdiagnosed as depression, or schizophrenia.
"This can lead to inappropriate treatment being prescribed and poor symptom control - so that appropriate treatments are prescribed and symptoms can be better controlled."
Andrea Sutcliffe, deputy chief executive of NICE, agreed: "Bipolar disorder often goes unrecognised or mis-diagnosed and more needs to be done to raise awareness of the condition and the fact that there are effective treatments available.
"This guideline should help raise awareness by setting out how people with bipolar disorder should be identified and treated."
Bipolar is characterised by the presence of episodes of mania and depression.
During a manic period a person can feel elation, irritation, or both. They might feel over-confident and take unnecessary risks.
When they are depressed however they feel low, are often tired and might have sleep problems, feelings of worthlessness and guilt.
Some even have thoughts of committing suicide or self-harming.
But Dr Clare Lamb, consultant child and adolescent psychiatrist at North Wales adolescent service, Conwy and Denbighshire NHS Trust, said if patients are swiftly diagnosed their outlook is brighter.
"Early detection and effective treatment can result in recovery and a good quality of life," she said.
Margaret Edwards, of the mental health charity Sane, agreed that bipolar could be difficult to diagnose - and carried a high risk of suicide when symptoms went untreated.
She said: "These guidelines are important not only in equipping health professionals to recognise and treat the condition, but in informing those with the illness and their carers about the effective treatments available."