March 18, 2008 (Philadelphia) -- Taking allergy drops instead of enduring painful shots may someday become an option for people who are allergic to honeybee stings.
Immunotherapy using the ubiquitous allergy shot is the standard treatment for allergies to everything from insect stings to dust mites. Tiny amounts of the allergens are injected into the patient until tolerance develops.
The new study involved a different form of immunotherapy, called sublingual immunotherapy. It involves putting extracts of allergens under the tongue. Like the shots, sublingual immunotherapy reduces allergic sensitivity in many patients over time.
And it's never been used to treat sting allergies, even in Europe, says researcher Giovanni Passalacqua, MD, of the Allergy and Respiratory Diseases Clinic at the University of Genoa.
Honeybee Venom Drops vs. Placebo
The new study, presented here at the annual meeting of the American Academy of Allergy, Asthma and Immunotherapy (AAAAI), is the first attempt to determine if sublingual immunotherapy is effective against honeybee sting allergies, Passalacqua says.
The study involved 30 people with a history of local allergic reactions to honeybee stings. A local reaction is a large raised patch of pricked skin right in the area of the sting. These raised bumps are often called wheals.
The participants were randomly assigned to receive either sublingual immunotherapy in the form of honeybee venom drops placed under the tongue, or placebo drops.
Patients in the immunotherapy group got escalating doses of honeybee venom for six weeks, followed by a maintenance dose, given three times a week for six months.
"You hold the drop under the tongue for about one or two minutes, then swallow," Passalacqua says.
The Bee Sting Challenge
Then came the bee sting challenge. "We put insects in a jar and then put the jar on the patient's forearm" and looked to see what happened, he says.
It worked. The median diameter of the sting wheals in patients given sublingual immunotherapy dropped from about 8 to 3 inches. Looked at another way, wheal diameter was reduced by more than 50% in more than half of them.
"This was a very apparent and very significant reduction in the size of the reaction to the sting," Passalacqua says.
In contrast, there was no change in wheal diameter in the placebo group, and one person broke out in hives.
The findings show that sublingual immunotherapy against honeybee stings works, Passalacqua says.
Venom Shots Are Effective
The next step: Testing sublingual immunotherapy in patients who have more severe allergic reactions that spread far from the sting or that affect the entire body. Doctors call these systemic reactions; while uncommon, they can be life-threatening.
Clifford Bassett, MD, vice chair of AAAAI's public education committee and an allergist at Long Island College Hospital in Brooklyn, N.Y., says that if sublingual immunotherapy proves safe and effective in larger numbers of people, "it will offer an alternative treatment for our patients. It's always good to have multiple choices."
In the meantime, he tells WebMD, venom shots are more than 95% effective in reducing the risk of systemic reactions in people with honeybee sting allergies.
While not always possible, avoiding the bees in the first place is the first line of defense, Bassett adds. A few tips: avoid cologne and trash-collection areas where the insects congregate.