Human maximization test of falcarinol, the principal contact allergen of English ivy and Algerian ivy (Hedera helix, H. canariensis)

Abstract
In a human maximization test of 55 falcarinol isolated from Hedera helix, 10 of 20 subjects were sensitized. No subjects gave irritant reactions to 5%, 10 became sensitive to 1%, and 7 to 0.05%, with 3 of these giving 3+ to 4+ bullous reactions.