A cross-sectional study of adverse cutaneous drug reactions with special reference to reaction time

Background: Adverse cutaneous drug reactions (ACDRs) present with different morphologies and times of onset. Knowledge about the common drugs causing them, their reaction time (time interval between drug intake and the onset of symptoms), and the clinical presentations are helpful in identifying an offending drug, especially in the setting of multiple drug therapies, thereby reducing the morbidity and mortality associated with them. Aims: This study aims to identify causative drugs and clinical patterns of ACDRs in a tertiary care center and to estimate their reaction time. Methods: Sixty-two patients diagnosed to have ACDRs who attended the department of dermatology of a tertiary care teaching hospital during an 18-month period were selected for the study. They were classified into certain, probable, or possible categories as per the World Health Organization-Uppsala Monitoring Centre (WHO-UMC) classification. The frequency of each type of drug reaction, common causative agents, and reaction time of different drug reactions was analyzed. Results: Of the 62 patients, 40 (64.5%) were probable, 18 (29%) possible, and 4 (6.4%) were certain. The most common types of reactions encountered were fixed drug eruption (FDE) (13, 21%), drug hypersensitivity syndrome (12, 19.4%), and maculopapular rash (9, 14.5%). As a single group of drugs, antimicrobials were the most common causative agents (23, 37%) followed by anticonvulsants (16, 25.8%). As an individual drug, phenytoin was the most common causative agent (10, 16.1%), followed by paracetamol (7, 11.3%) and isoniazid (5, 8.1%). Reaction time varied from less than an hour for FDE and urticaria to 3–4 months for exfoliative dermatitis, lichenoid eruption, and folliculitis. Limitations: Small sample size was the major limitation. Conclusion: Reaction time varied from less than 24 h in FDE, urticaria, and angioedema to 3–4 months in exfoliative dermatitis, lichenoid eruption, and folliculitis.