The other parts of the body were relatively free. Full blood picture including platelet count was within normal limits. The patient was advised to stop taking prazosin and after three weeks the rash disappeared, leaving mild hyper-pigmentation. These are common due to the pharmacologic action of the drug and usually diminish with the continuation of therapy or reduction in dosage. Drugs which cause purpura are arsenic, bismuth, barbiturates, carbromal, ethyl stilbesterol, phenacetin, sulphonamide, food additives such as tartarazine and tolbutamide, etc.3 Carbromal, a sedative, produces a well-recognized and unique pattern of purpura.
Drugs can cause vascular or non-thrombocytopenic purpura.
A good history is often helpful in the diagnosis of drug-induced purpura, which usually resolves upon withdrawal of the offending drug. Nonspecific rashes due to prazosin are seen but purpuric eruptions are rare. Since prazosin is commonly administered, it is useful to look for purpura when patients present with drug rash, especially when it involves the lower limbs. 10990 Penang, Malaysia References 1. Ruzicka T, Ring J. Hypersensitivity to prazosin.