The contact dermatitis due to this weed has long been recognized. It has been observed that chances of getting sensitized to the weed are high, when a person comes in constant contact with the weed for a period ranging from 3 to 12 months. In one case, a lady aged forty years was drawing out water from her skin to the extent of 1.0 to 1.5 litres per day during peak season of Parthenium growth. Parthenium is reported to be responsible for largest number of airborne contact dermatitis in India. Almost every part of the plant except root is reactive. The reaction was mainly over the sun-exposed area.