Peanut allergy is on the increase

The drug, which is still at an experimental stage, is not a cure for the allergy.

But doctors believe that a monthly jab may help to reduce the risk of a violent reaction to eating one or two peanuts accidentally.

However, the drug is at least three years away from going on the market.

And its critical third round of tests has been stalled by legal infighting among the three companies - Genentech, Tanox Inc and Novartis Pharmaceuticals - with rights to it.

Anything that reduces the everyday risks will improve the quality of life for the large number of families affected David Reading

The drug, TNX-901, is designed to block the action of immunoglobulin-E, or IgE, a molecule that plays a major part in asthma and allergies.

In a study, 84 people with peanut allergy were given monthly shots of the drug, or a dummy injection.

Four different doses of the drug were tested.

Those on the highest dose could safely handle an average of almost nine peanuts' worth of peanut flour after four months of treatment. Five ate the equivalent of 24 peanuts without reacting.

Other symptoms

Researcher Dr Hugh Sampson, of Mount Sinai Medical School in New York, said: "That's a pretty impressive amount."

The drug also protected people from the even tinier amounts of peanuts that can be present in the air.

In addition, several participants reported that other food allergies were lessened, and hay fever symptoms disappeared.

Among those who took part in the study was Allison Rush, 15, who was so sensitive to peanuts that the equivalent of just one-60th of a nut was enough to trigger an allergic reaction.

After four monthly injections, it took the equivalent of six peanuts to bring on such an anaphylactic attack.

Her mother Bonnie said: " really can't imagine life for my daughter without this drug.

"It's completely changed her quality of life, her outlook on life."

David Reading, director of the UK Anaphylaxis Campaign, said: "We are cautiously optimistic.

"People with peanut allergy often find that life is extremely uncertain and stressful.

"Parents of peanut-allergic children sometimes talk of 'playing Russian roulette at mealtimes.'

"Anything that reduces the everyday risks will improve the quality of life for the large number of families affected."

The research was presented to a meeting of the American Academy of Allergy, Asthma and Immunology in Denver. It will be published in the New England Journal of Medicine.