Drinking a strong cup of coffee can relieve the symptoms of hayfever and prevent severe allergic reactions, claim researchers.

They said they had successfully prevented even acute allergic responses such as anaphylactic shock, which can kill.

Caffeine may be effective in chronic allergic disorders

Scientists had previously discovered that coffee cold have anti-allergic properties because of its ability to reduce the release of histamine from mast cells.

In susceptible people, mast cells release histamine into affected tissues when triggered by substances such as pollen and dust.

The researchers at Wongkwang University in South Korea are the first to investigate its role in stopping anaphylactic shock.

They injected rats with a synthetic compound called 48/80 to activate mast cells and rapidly release large amounts of histamine.

In untreated rats, the injections caused fatal allergic reactions, but when they repeated the test giving the rats an infusion of caffeine, many survived.

Levels of caffeine as low as 0.1 milligrams per kilogram - equivalent to a strong cup of coffee - cut the death rate by half, reported New Scientist magazine.

Hopeful

Hyung-Min Kim, who led the research, was hopeful caffeine could have a similar effect in humans.

He said: "Caffeine may be effective in chronic allergic disorders."

And it might be useful in preventing everyday allergies, he added.

Francesca Levi-Schaffer, a pharmacologist at the Hebrew University-Hadassah Medical School in Israel, said: "Caffeine can be a preventative drug if given by inhalation to asthmatic patients."



