An antigen from Parthenium hysterophorus Linn.

The increasing incidence of contact dermatitis due to the wild growth of the weed Partheium hysterophorus Linn. in many parts of India has prompted chemical analysis coupled with clinical testing to isolate the offending agent. Results are present to show that parthenin, a sesquiterpene lactone, is the major antigen which produces contact dermatitis in sensitive human beings.