More than a million asthma sufferers may not actually have the condition and could be taking unnecessary medication the NHS watchdog has warned.
The National Institute of Clinical Excellence (Nice) has warned that around one third of adults show no clinical signs of the chronic lung problem and could be at risk from the side effects of asthma drugs.
The watchdog has drafted new guidelines for doctors which are currently out for consultation and could become standard by the summer.
The new guidance advises doctors to use more clinical tests to back up their judgement and avoid the danger of wrongly labelling someone as having asthma.
Prof Mark Baker, director of clinical practice at NICE, told the BBC: “Accurate diagnosis of asthma has been a significant problem which means that people may be wrongly diagnosed or cases might be missed in others.
The new guidelines state: “Diagnosis is principally based on a thorough history taken by an experienced clinician.
“It is therefore not surprising that studies of adults diagnosed with asthma suggest that up to 30 per cent do not have clear evidence of asthma.”
The NHS spends around £1 billion a year treating and caring for the 5.4 million people with asthma but many may be suffering from other respiratory diseases