Low-Dose Oral Minoxidil and Associated Adverse Events: Analyses of the FDA Adverse Event Reporting System (FAERS) With a Focus on Pericardial Effusions.

Background: Low-dose oral minoxidil (LDOM) is used to treat hair loss, but the literature on its safety profile is relatively sparse.

Aims: Using the FDA Adverse Event Reporting System (FAERS) database, we determined signals for adverse events (AEs) with LDOM use.

Methods: Four sets of case/noncase study disproportionality analyses were conducted to determine reporting odds ratio (ROR) for 10 AEs including pericardial effusion (PE). The oral minoxidil dose ranges were: (i) ≤1.25 mg (i.e., 0-1.25 mg), (ii) ≤2.5 mg (i.e., 0-2.5 mg), (iii) ≤5 mg (i.e., 0-5 mg), and (iv) ≤10 mg (i.e., 0-10 mg).

Results: For ≤1.25 mg, we detected a signal for PE (ROR = 16.41, 95% CI: 2.29, 117.37, p < 0.05). For ≤2.5 mg, the analyses detected a signal for PE (ROR = 13.30, 95% CI: 5.96, 29.68, p < 0.05); the ROR in the absence of cardiac impairment was 5.34 (95% CI: 1.33, 21.37, p < 0.05); in the presence of cardiac impairment, the ROR was 49.42 (95% CI: 18.27, 133.66, p < 0.05). A signal for PE was also detected at ≤5 and ≤10 mg. For PE, there was a significant (p < 0.05) association with a patient outcome of "life threatening" only at the ≤10 mg dose range.

Conclusions: Our study, the first FAERS-based signal detection study for LDOM, found significant associations between LDOM use and several AEs. In the absence of causal evidence, these correlations warrant more attention regarding safe use of LDOM. Until more safety data are available, we recommend using LDOM at the lowest effective dose (≤5 mg/day).