Peanut-allergic patients, particularly adolescents, need to be counseled on the risks of kissing someone who has recently eaten peanuts or peanut-containing products, even if that person brushed their teeth afterwards, a researcher said at the American Academy of Allergy, Asthma and Immunology’s annual meeting in Miami Beach.

Despite the recent conclusion from the Quebec coroner’s office that a 15-year-old girl with a severe peanut allergy did not die from kissing her boyfriend after he ate a peanut butter sandwich, as was theorized, “there is a risk for allergens to be transferred in saliva,” Dr. Jennifer M. Maloney of Mount Sinai Medical Center in New York noted at a press conference.

“Several investigators,” she continued, “have looked at populations of food-allergic individuals and have found that significant proportions of them do have reactions via kissing.”

Maloney and colleagues evaluated the level of peanut protein in saliva, and methods to remove it, in 10 volunteers after they ate a sandwich containing 2 tablespoons of peanut butter.

Saliva concentrations of the major peanut allergen, varied markedly immediately after ingestion. The levels ranged from below the level of detection to very high levels.

By one hour after the meal, allergen levels were undetectable in the saliva from six of the seven individuals who had positive test results after the meal. Allergen levels were undetectable in all subjects within 4.5 hours.

According to Maloney, none of the methods of trying to get rid of all traces of peanut - brushing the teeth, brushing and rinsing, rinsing alone, or chewing gum - consistently reduced the allergen levels to below the level of detection. “Everything reduced the amount, but nothing uniformly removed it,” Maloney said.

“It is not enough,” she pointed out, “for clinicians just to tell peanut-allergic individuals to simply have their partner brush their teeth or rinse their mouth and think that this is a safe approach.”

“The safest approach,” Maloney advised, “would be for the partner of a food-allergic individual to completely avoid the food. If this is impossible, we think that waiting several hours, possibly eating a meal in between, would reduce the levels below a level that would pose a critical problem.” A larger study currently underway may provide more definitive answers.