Background: Acetaminophen (paracetamol-P) is a widely used analgesic-antipyretic drug with no antiinflammatory effects and its rate of adverse hypersensitivity reactions is very low. On the contrary non-steroidal anti-inflammatory drugs (NSAIDs) are commonly involved in side effects. Celecoxib (CE)is a novel drug, with high selectivity and affinity for COX-2 enzyme.

Objective: We evaluated the tolerability of CE in a group of patients with documented history of adverse cutaneous reactions to P and to classic NSAIDs.

Methods: We studied 29 patients with hypersensitivity to P and classic NSAIDs. The diagnosis of P-induced skin reactions was based on in vivo challenge. The placebo was blindly administered at the beginning of each challenge. After three days, a cumulative dosage of 200 mg of CE in refracted doses was given. After 2-3 days, a single dose of 200 mg was administered. All patients were observed for 6 hours after each challenge, and they were controlled again after 24 hours to exclude delayed reactions. The challenge was considered positive if one or more of the following appeared: erythema, rash or urticaria-angioedema.

Results: No reaction was observed with placebo and twenty eight patients (96.5 %) tolerated CE. Only one patient developed a moderate angioedema of the lips.

Conclusion: Only one hypersensitivity reaction to CE was documented among 29 P-intolerant patients. Thus, we conclude that CE is a reasonably safe alternative which can be used in subjects who do not tolerate P.

Key words: Celecoxib, drug allergy, cutaneous adverse reactions, NSAIDs, paracetamol.