The prevalence and risk factors of drug allergy in Sri Lanka—a multi-centre cross-sectional observational study (2024–2025)

Background There is a huge burden of drug allergy (DA) in High-Income Countries and is a major impediment to clinical management, adversely affecting outcomes. Data regarding DA from low-and middle-income countries (LMICs) are sparse. Also, there is a vast unmet demand for DA services in LMICs. We aimed to determine the prevalence of self-reported and physician-documented DAs in Sri Lanka and to explore potential risk factors associated with DA labels. Methods Cross-sectional, observational study was carried out among adults presenting to outpatient clinics in selected secondary and tertiary care centres during December 2024 to April 2025. A standardised e-proforma in a 1-1 interview captured details. Potential risk factors were explored using multivariable logistic regression. Findings Total number of respondents was 12,491: Females: 8410 (67.4%) and males: 4081 (32.6%). Mean age (SD) was 55.1 (14.4) years and 727 reported allergies to 868 drugs; prevalence=5.8% (95% CI: 5.42–6.24); allergy to ≥2 drugs=0.74%. Most common reported were antibiotics (41.5%; penicillins most common), nonsteroidal-anti-inflammatory drugs (13%), and paracetamol (10.6%). In the mixed-effect logistic model, odds of DA were lower among males (AOR: 0.74, 95% CI: 0.61–0.88; p < 0.001), and Tamil ethnicity (AOR: 0.67; 95% CI: 0.51–0.89; p=0.005). Higher odds were observed in 50–<60-year (AOR: 1.55; 95% CI: 1.20–1.99.; p < 0.001) and 60–93-year (AOR: 1.38; 95% CI: 1.08–1.77, p=0.011) age groups and allergic, endocrine, cardiovascular, rheumatological, neurological, and haematological comorbidities. Interpretation There is a high burden of reported DA in Sri Lanka. This is compounded by an unmet demand for DA services highlighting a need for capacity building.