That news comes from researchers including Mary Morris, MD, of Allergy Associates of La Crosse in La Crosse, Wis.
They studied 115 people with a history of severe skin reactions to poison ivy who were treated at their clinic over the past 15 years.
The treatment was a small amount of poison ivy extract placed under the tongue. The goal was to train the body's immune system not to overreact to poison ivy.
The patients took skin tests to see if the treatment helped.
Those tests showed that after treatment, patients had a much higher threshold for allergic skin reactions to poison ivy.
Further tests are needed. If those tests go well, the treatment may help people whose jobs and hobbies expose them to poison ivy, the researchers note.