Treatment of erythema nodosum and nodular vasculitis with potassium iodide.

Twenty-four of twenty-eight patients with erythema nodosum and sixteen of seventeen patients with nodular vasculitis responded to treatment with potassium iodide. Relief of symptoms occurred within 2 days. The average duration of treatment was 3 weeks and the lesions took an average of 2 weeks to resolve. The possible mode of action of potassium iodide is discussed and an immunosuppressive effect mediated by heparin is suggested.