Thirteen patients with atopic dermatitis were treated orally with guanethidine in daily doses of up to 50 mg for 10 to 30 days. Only six patients experienced a decrease of itching. The delayed blanch reaction did not disappear except in one patient.
During early treatment eight patients exhibited marked reddening, edema, and itching of the skin in the face, especially periorbitally. Nine had orthostatic complaints and four had abdominal symptoms. Guanethidine has only a doubtful antipruritic effect in atopic dermatitis in the dosage used.
In addition, the delayed blanch reaction after intracutaneous injection of methacholine was studied in 124 dermatological patients and 40 persons without skin diseases. The reaction was found in 15 out of 16 (94%) patients with atopic dermatitis, and in 22% to 30% of patients in other groups. The delayed blanch reaction is characteristic but not specific for atopic dermatitis and the atopic state.