Azathioprine as a corticosteroid sparing agent for the treatment of dermatitis caused by the weed Parthenium.

Air-borne contact dermatitis caused by Parthenium hysterophorus is a serious problem in India. Patients with this condition have to use corticosteroids regularly in order to maintain clinical remissions, but prolonged usage causes serious side-effects. The weed cannot be eradicated. We have used 3 therapeutic regimens with azathioprine, which led to an effective control with minimal side-effects even when used for long periods. A total of 22 patients (group I) were given 50 mg azathioprine twice a day; 11 patients (group II) received 50 mg azathioprine per day and 300 mg azathioprine every 28 days, and 10 patients (group III) were given 50 mg azathioprine twice a day along with 300 mg azathioprine every 28 days. The duration of treatment varied from 6 months to 3 years. Twenty patients in group I and 9 patients each in groups II and III had complete remission. Nine, 7 and 6 patients in the respective groups needed additional oral betamethasone 1-2 mg per day for brief periods only during the peak season in order to maintain complete remission. One patient in each group had only partial relief. The need for oral betamethasone during the second and the third year was further reduced. One patient each in group I and group II could not continue azathioprine due to the side-effects of the drug.