Cutaneous adverse reactions – 10 cases

Vasculitis due to allopurinol

Hypersensitivity or leukocytoclastic vasculitis is an example of type 3 immune complex reaction. It may arise one to three weeks after starting a drug and is sometimes accompanied by eosinophilia. In many cases, it can be difficult to distinguish a drug-induced vasculitis from one due to underlying infection, connective tissue disease, malignancy or other systemic condition.
Cutaneous vasculitis is characterised by palpable purpura, i.e., non-blanching erythematous or purple macules, papules and plaques, sometimes accompanied by blisters. In some cases, fever, myalgia, arthritis and abdominal pain may be present.
Specialist advice should be obtained. New drugs should be stopped and underlying disease should be treated. Investigations should screen for causes of vasculitis and establish the degree of internal organ involvement.
In most cases, no specific treatment is required for the cutaneous eruption. It generally resolves within a few weeks, but crops of new lesions may arise for up to several months depending on the cause.

The drugs that most commonly cause cutaneous vasculitis are allopurinol, antiinflammatories, cimetidine, antibiotics, sulfonamides and thiazides. There are isolated reports of vasculitis due to a wide range of medications.