Penicillin allergy is more likely to develop in women than in men, even after factoring in the effects of other allergy risk factors, according to study findings published in the of the Annals of Allergy, Asthma, and Immunology.

The rate of individuals reporting they are allergic to penicillin ranges from 1 percent to 10 percent, and the rate of life-threatening reactions to this antibiotic is estimated to be 0.01 percent to 0.05 percent, note Dr. Miguel A. Park, of the Mayo Clinic, Rochester, Minnesota, and colleagues. ”

In a chart review study, the researchers determined the rates of positive penicillin skin test (PST) results, according to sex, in patients with a history of penicillin allergy who were undergoing a medical evaluation.

A total of 1,921 patients were included in the study. Of these, 1759 underwent PST and 157 did not. Five medical records were not available for review. The average patient age was 60 years old.

The PST was positive in 64 patients (4 percent). Of these 64 subjects, 53 (83 percent) were female and 11 (17 percent) were male, a statistically significant difference.

After performing additional analysis, taking in consideration the effects of age, history of multiple drug allergies, and time elapsed from the initial penicillin reaction to the PST, female sex again conferred a significant risk of a positive PST reaction.

“Females were also 2.6 times more likely than males to report multiple drug allergies,” Park’s team reports. There have also been previous reports of studies that found female sex to be a risk factor for adverse drug reactions in general.

SOURCE: Annals of Allergy, Asthma, and Immunology, July 2007.