Photochemical reactions of Heracleum laciniatum. Influence of dimethyl sulphoxide and corticosteroids.

Phytophotodermatitis of Heracleum laciniatum is quite common in Tromsø during the summer months. The clinical picture varies from mild to severe erythematous reactions with or without vesicles or bullae on the exposed parts of the body. Phototoxic reactions of Heracleum laciniatum are reported. The influences on phototoxic reactions by bergapten (5-methoxypsoralen) and UV-A by treating the skin with a membrane labilizing agent, dimethyl sulphoxide (DMSO), and a membrane stabilizing agent, the steroid desoximethasone, are evaluated.