Fixed drug eruption and intradermal provocation tests.

OBJECTIVE To determine the role of Intradermal Provocation (IDP) tests in Fixed Drug Eruption (FDE). STUDY DESIGN Quasi-experimental study. PLACE AND DURATION OF STUDY Dermatology Unit, Shaikh Zayed Hospital, Lahore, from August 2004 to July 2006. METHODOLOGY The tests were performed in 96 patients in two stages. At stage I, suspected drugs were given intradermally. Changes at injection site in FDE lesions or any systemic effects were observed. In patients showing no response to IDP, Oral Provocation (OP) was performed (stage II) and its effects in FDE lesions or any systemic effect were observed. The positive response of FDE lesions after IDP and OP were compared with local changes at injection site. Control intradermal tests were repeated in normal persons with drugs and in FDE patients with distilled water on normal skin. RESULTS At stage I, 46 positive cases had local signs of erythematous indurated nodule with or without hemorrhagic centre, urticarial weal with hemorrhagic centre and erythematous indurated nodule with central vesicle. At stage II, 41 patients had similar local signs. The changes at injection site to those of FDE lesions were compared. Z-test for proportions showed no significant difference between groups (p-value > 0.05). Control tests were negative. CONCLUSION The drug producing erythematous indurated nodule with or without hemorrhagic centre, vesicle or urticarial weal with hemorrhagic centre at injection site was the most likely drug causing fixed eruption.