Clinical study and skin tests of patients with drug eruptions

Background: Drug reactions are common problems in hospital inpatients and outpatients. Reliable diagnosis is essential but often difficult. Objective: This study attempts to define the clinical features and causative drugs in the patients with drug eruptions, and to evaluate the diagnostic value of skin tests. Methods: Sixty one patients with drug eruptions were reviewed clinically. In 18 patients, patch and prick tests were performed using suspected drugs. Results: 1. The highest incidence of drug eruptions was observed in the third and forth decades (44.2%) and there was no sexual predominence. 2. The most frequent latent period was 4 hours to 1 week (49.2%). 3. The common morphological features were exanthematous eruptions (57.3%), urticaria (14.8%) and fixed drug eruptions (11.5%). 4. The major causative drugs were antibiotics (cephalosporin, ampicillin), antipyretics/anti-inflammatory analgesics (aspirin, piroxicam) and CNS depressants (diphenylhydantoin). 5. Clinical manifestations according to possible causative drugs were as follows; exanthematous eruptions by antibiotics, antipyretics/analgesics, herbs, CNS depressants, prophylthiouracil and captopril; urticaria by antibiotics and herbs; fixed drug eruption by sulfonamide, antipyretics/analgesics and phenobarbital; acneiform eruptions by diphenylhydanton and isoniazid; Stevens-Johnson syndrome by ampicillin, sulfonamide, aspirin and piroxicam, erythema nodosum by sulfonamide, and lichenoid drug eruptions by propylthiouracil. 6. Positivity to patch and prick tests was shown in 2 of the 18 patients and in 1 of 18 patients, respectively. Conclusions: The most frequent clinical feature of the drug eruptions were exanthematous in nature and the most common causative drugs were antibiotics, as suspected. To search for the causative drug of the drug eruption, the only usual methods of patch and prick tests were not sufficient in our study.