Monthly allergy shots can lessen the torment of hay fever for years after the shots are stopped, a study found.
Researchers at the Imperial College School of Medicine in London found that patients who received immunotherapy monthly for three or four years reported weaker symptoms of the grass-pollen allergy three years after stopping the treatment.
"They may never relapse into symptoms as severe as what they had originally," said Samantha Walker, one of the study's authors.
The research is reported in today's edition of the New England Journal of Medicine.
The British researchers asked patients to keep detailed diaries of their hay fever symptoms in 1993, '94 and '95.
The study found little differ-ence between the severity of symptoms reported by patients who had continued allergy-shot treatment during the three-year trial and those who got dummy shots.
Those who had never had immunotherapy reported much more severe symptoms than the others.
The researchers also found that the immune systems of the patients who discontinued treatment produced less of the allergen-fighting substances that cause runny noses and other hay fever symptoms than the untreated group.
Those who maintained allergy-shot treatment had even fewer of those symptoms.
The researchers said their findings and other studies suggest that starting immunotherapy sooner after an allergy appears, particularly in children, could prevent the allergy from becoming severe and prevent development of additional allergies.