Angry back or the excited skin syndrome. A prospective study.

Allergens eliciting weak positive reactions were retested to ascertain their reproducibility. Weak positive patch test reactions, concomitant to other weak or strong positive reactions, were retested after 3 weeks in 61 patients. 79 reactions were retested; 35 (44.3%) were negative. Allergens which are marginal irritants, e.g., formaldehyde, often gave weak positive reactions which were lost at retesting. In patients without dermatitis but with several strong positive reactions, lost reactions were frequently encountered, suggesting that strong reactions induced a state of hyperirritability. False positive reactions were often found in the proximity of strong reactions. We attempted to develop a nonspecific irritant (sodium lauryl sulfate) as a hyperirritability marker. A correlation between the score of this test and false positive reactions was not found. It is concluded that weak positive reactions should not be accepted as a proof of sensitization. The allergens eliciting these reactions should be retested at a later date.