SUNDAY, Nov. 14 (HealthDay News) -- The course of true love may not run smoothly for some people with highly sensitive allergies, experts say, since kissing or other intimate contact can pose risks for sometimes serious reactions.

In fact, allergens can linger in a partner's saliva up to a full day following ingestion, irrespective of toothbrushing or other interventions, according to Dr. Sami Bahna, president of the American College of Allergy, Asthma and Immunology (ACAAI), which is holding its annual meeting this week in Phoenix.

Allergic reactions from kissing are relatively uncommon, but they do occur.

"We're talking about those few whose immune system can react vigorously to a minute amount of allergen," noted Bahna, who also serves as chief of allergy and immunology at Louisiana State University Medical School in Shreveport. "For these people, yes, a very little quantity of food or medicine on the lips or the mouth or the saliva can cause a problem. And for these people we're not just talking about a passionate kiss. Even a non-passionate kiss on the cheek or the forehead can cause a severe reaction to this kind of extremely sensitive allergic individual."

The ACAAI estimates that more than 7 million Americans suffer from food allergies -- about 2 percent to 3 percent of adults and 5 percent to 7 percent of children.

It's not unusual for people with allergies to experience a reaction in the form of lip-swelling, throat-swelling, rash, hives, itching, and/or wheezing immediately after kissing a partner who has consumed an identified allergen. Bahna said some highly sensitive people can be affected hours after their partner has absorbed the culprit substance, because the partner's saliva is still excreting allergen.

One expert said that when it comes to preventing kissing-related allergic reactions, honesty -- and a little proactive guidance -- is key.

"People need to know that intimate contact with individuals who've eaten or consumed suspect foods or medicines can also cause problems," said Dr. Clifford W. Bassett, a clinical instructor at New York University's School of Medicine, New York City, and an attending physician in the allergy and immunology department of Long Island College Hospital. "So, for people with a significant food allergy it's always better to play it safe by making sure that everyone knows that in all situations these foods are strictly off-limits."

He believes it's vital that these individuals, "start a dialogue about [the allergy] with their friends, their colleagues, and their loved ones. In fact, I feel strongly that individuals with serious allergies -- and I'm not talking about trivial allergies, but those with life-threatening conditions -- have a kind of obligation to themselves and to the people they care about to start this discussion. Because it can and will save lives."

Bahna agreed, advising that the partners of people with these types of sensitivities avoid the problematic food or medication altogether for anywhere from 16 to 24 hours before initiating intimate contact. Toothbrushing and rinsing the mouth prior to contact should also help, although it can't eliminate the risk, he said.

And kissing isn't the only form of romantic activity that can trigger allergic reactions in the highly sensitive. The ACAAI notes that intercourse can pose its own hazards, given that some patients are allergic to chemicals found in spermicides, lubricants and/or latex condoms.

Even semen can prompt an allergic reaction in some, as can the more general emotional and physical exertion of intercourse itself.

When it comes to semen allergy, Bahna said antihistamines can sometimes help with mild issues, as can immunotherapy treatments offered by allergists. Condoms can also help, as long as a person is not allergic to latex.

Bahna stressed that reactions severe enough to interfere with romance are relatively rare.

"I do not want this discussion to cause all people with allergies to live in fear," he said. "It depends on the particular sensitivity of the immune system. While allergies in general are common, the degree of sensitivity in people varies widely. Most people get a mild reaction from an allergen. So if your girlfriend or your wife is not very allergic to peanuts, for example, she will not be affected by a kiss from a person who ate peanuts."

More information

For more on food and drug allergies, visit the U.S. National Institutes of Health.