BACKGROUND:Recent studies show that patients with multiple nonsteroidal anti-inflammatory drug (NSAID) intolerance are frequently characterized by autoreactivity; this can be detected by autologous serum skin test (ASST). OBJECTIVE:To assess whether the autologous plasma skin test (APST), a test that was recently shown to be more sensitive than ASST, may be usefully employed as a predictive test for multiple NSAID intolerance in patients with a history of single NSAID intolerance. METHODS:Thirty otherwise normal adults with a history of acute urticaria following the ingestion of one single NSAID underwent an APST before being challenged with a COX-1-inhibiting NSAID other than the offending drug. RESULTS:Sixteen patients experienced urticaria following the ingestion of the alternative NSAID and were therefore classified as multiple NSAID reactors; all 16 (100%) scored positive on APST. In contrast only 3/14 patients finally classified as single NSAID reactors were positive on APST (p < 0.001). The positive and negative predictive value of APST for multiple NSAID intolerance were 86 and 100%, respectively. CONCLUSION:In patients with a history of acute urticaria induced by a single NSAID APST can be usefully employed to detect patients that are prone to react to NSAID other than the original offending one.