More than half of people with asthma say their symptoms can be triggered by laughter, a survey reveals.
Laughter can trigger asthma symptoms
The US research, involving 235 patients with asthma, found that 56% had laughter-induced asthma.
Nobody knows how laughter brings on asthma, but it might involve hyperventilating, say the New York University authors.
They told an American Thoracic Society meeting how it might be a sign that a person's asthma is not well controlled.
No laughing matter
Asthma that was triggered by laughter did not seem to cause more asthma flare-ups requiring emergency room visits or hospitalisations compared with other types of asthma, said lead researcher Dr Stuart Garay.
"But patients did report that during times when their asthma is well controlled they can laugh for longer without getting asthma symptoms.
"That suggests that laughter-induced asthma may be a sign that a person's asthma isn't as well controlled as it could be," he said.
He said that laughter was not as well recognised as a trigger as factors such as pollen, fumes and dust mites, even though it is equally or more common than these.
He said for some even mild laughter or a chuckle is enough to set off coughing. A spokeswoman from Asthma UK said: "We know that emotion, stress and laughter can all trigger asthma attacks in people with asthma.
"However, if you find that you are often experiencing asthma attacks as a result of laughing it could be a sign that your asthma is not well controlled.
"Speak to your GP or asthma nurse about reviewing your treatment or call the Asthma UK Advice line on 08457 01 02 03 for further advice."