Allergy sufferers urged to be cautious kissers

People who suffer from food allergies not only have to be careful about what they eat but also about who they kiss, according to a warning from the Mayo Clinic in the US timed to coincide with Valentine's day last week.

In the February issue of Mayo Clinic Proceedings​, David Steensma, a haematologist at the clinic, wrote about the case of a 20-year-old woman who is allergic to shellfish and experienced a severe allergic anaphylactic reaction immediately after she kissed her boyfriend. The boyfriend had eaten several shrimp less than an hour earlier.

"It is important to warn susceptible patients that food does not actually have to be eaten to trigger an allergic reaction,"​ said Dr Steensma. "Touching the offending food and kissing or touching someone who has recently eaten the food can be enough to cause a major reaction."​

Kissing has been recognised only recently as a vector for transmitting food allergens, Dr Steensma added.

The woman experienced a reaction in her lips and skin, had throat swelling, diffuse flushing, abdominal cramps, nausea and wheezing with symptoms beginning less than one minute after she kissed her boyfriend. She was treated at the emergency department of a Mayo Clinic-affiliated hospital, where she was given a prescription for an epinephrine injection kit, urged to scrupulously avoid shellfish exposure and instructed to follow up with her primary-care physician.

The couple worked at a seafood restaurant, and the woman sometimes wore gloves while serving food. However, the night of her severe reaction, she reported no distress or symptoms prior to the kiss. The patient had repeatedly touched shellfish while on the job and, as a consequence, had experienced a series of mild allergic reactions.

These minor reactions may have served to "prime " her immune system to produce more antibodies directed at crustacean proteins, a phenomenon that is similar to reactions people have to seasonal allergens such as ragweed and other noxious pollens.

"This case report underscores the importance of carefully counselling all patients who are allergic to food that they must avoid exposure to offending proteins via all potential routes of contact, including kissing and touching,"​ Dr Steensma said. "Carrying an injectable epinephrine kit - and having been instructed in its use - and wearing emergency medical information, such as a Medic-Alert bracelet, may also be helpful for patients susceptible to severe allergic reactions."​