Nickel dermatitis: the reaction to oral nickel challenge.

Pompholyx in nickel-sensitive subjects can be induced by orally-administered nickel, but only by a high dose. Ingestion of 5.6 mg nickel consistently worsened the pompholyx, often with a mild toxic erythema or patch test site flare, but lower doses of nickel failed to excite reactions more frequently than did a placebo, in a double-blind study. The metabolism of nickel is complex and there was considerable variation between three normal individuals in their absorption and excretion of an orally-administered nickel load. Patients may show similar variability which could be of importance clinically, although in only one of five subjects with acute eczema was the serum nickel raised, and then only marginally. The exact role of dietary nickel in perpetuating the hand dermatitis of sensitive subjects remains unclear.