Patches take sting out of canker sores.

Canker sores, painful ulcers that form inside the mouth, can be slow to heal. In the absence of a cure, people often resort to numbing agents and wait out the lesions.

A patch that dispenses licorice extract directly onto the sores lessens their duration and dramatically eases pain, a preliminary test shows. Inventor Jeffrey T. Haley, a biochemist at Orahealth Corp. in Bellevue, Wash., presented the findings at a meeting of the International Association for Dental Research (IADR) in New Orleans in March.

Haley and his research team identified 46 people who each had a new canker sore. Half of the patients received patches--discs about the size of a child's fingernail--while the others went untreated. After 3 days, about four-fifths of the treated people reported no pain, while only two-fifths of the untreated volunteers did. Moreover, after 7 days, canker sores had shrunk by 90 percent in the treated group but had grown slightly in the untreated people.

"These results are very encouraging;' says Christopher H. Fox, a dentist and IADR executive director. "Decreasing the pain and speeding the healing is a positive benefit, [but] we would want further studies with a larger sample size and a control group to verify this,' he says.

The patches, marketed as Cankermelts by Orahealth, adhere to the sores for 2 to 6 hours. Study volunteers replaced their patches during waking hours.

People had tried licorice gargle as a canker sore remedy in the 1960s and 1970s, but it didn't catch on. Researchers don't know what causes canker sores or why licorice seems to work, Haley says.