leukocytoclastic vasculitis
"I've had Vascultis along with Lupus for 10 years. The pain, welts, sensitivity was unbearable. Dapsone was prescribed 1 year later for the Vasculitis. It saved me from pain along with prednisone.  It works great.  It seems to be on a 24 hour cycle.  If I miss my dose or go way past the time I take my medicines I start breaking out. Please heed the warning of sunlight sensitivity.  If I'm out in the sun for a long time, within hours I'm covered with the painstaking welts.  Then I have to ride it out for a day or two even if I take my dapsone on time."