Risk and timing of isotretinoin‐related laboratory disturbances: a population‐based study

Introduction Uncertainty surrounds the optimal routine laboratory monitoring in acne patients treated with isotretinoin. Objective Our aim was to evaluate the risk of mild and severe laboratory abnormalities in patients with acne starting isotretinoin versus oral antibiotic treatment. Methods A global population‐based retrospective cohort study assigned two groups of patients with acne‐prescribed isotretinoin ( n = 79,012) and oral antibiotics ( n = 79,012). Comprehensive propensity‐score matching was conducted. Results Compared to acne patients treated with oral antibiotics, those under isotretinoin demonstrated an increased risk of grade ≥3 hypertriglyceridemia (hazard ratio [HR], 7.85; 95% confidence interval [CI], 5.58–11.05; P < 0.001) and grade ≥3 elevated aspartate transaminase (AST) levels (HR, 1.45; 95% CI, 1.13–1.85; P = 0.003) within the initial 3 months of treatment. The absolute risk of these abnormalities among isotretinoin initiators was 0.4% and 0.2%, respectively. The risk difference of these findings was clinically marginal: 3 and 1 additional cases per 1,000 patients starting isotretinoin, respectively. There was no significant risk of grade ≥3 impairment in cholesterol, alanine transaminase, gamma‐glutamyl transferase, or creatinine levels under isotretinoin. Most laboratory abnormalities were documented 1–3 months after drug initiation in time‐stratified analysis. Conclusion Isotretinoin is associated with a clinically marginal increased risk of severe hypertriglyceridemia and hypertransaminasemia. Routine blood testing should be performed 1–3 months after commencing therapy.