Exploring the Efficacy and Safety of Topical Phenytoin in Androgenetic Alopecia: A Clinical Investigation

ABSTRACT Background Phenytoin, a widely used antiepileptic drug, is known for its proliferative effects on fibroblasts and keratinocytes, as well as its stimulatory influence on angiogenesis. One of its notable side effects is hirsutism, which suggests a potential role in hair growth promotion. Aims This study aimed to evaluate the safety and efficacy of a topical 5% phenytoin solution in men with androgenetic alopecia (AGA). Methods In this 16‐week, open‐label clinical trial, adult male participants with AGA applied a 5% phenytoin solution twice daily. TrichoScan analysis and standardized global photographs were employed at baseline, week 8, and week 16 to assess changes in total hair count, hair density, anagen‐to‐telogen ratio, and follicular units. Subjective assessments of hair condition and scalp oiliness were obtained at each visit using a patient satisfaction scale. Adverse events were monitored throughout the study period. Results Statistically significant improvements were observed in total hair count from baseline (158.07 ± 37.65) to week 16 (183.21 ± 44.63) ( p ‐value = 0.010). Similarly, hair density significantly increased from baseline (174.99 ± 41.70 number/cm 2 ) to week 16 (202.39 ± 49.67 number/cm 2 ) ( p ‐value = 0.011). Number of total follicular units also exhibited a significant increase from baseline (90.07 ± 16.85) to week 16 (98.07 ± 19.67) ( p ‐value = 0.013), as did follicular unit density from baseline (99.71 ± 18.66 FU/cm 2 ) to week 16 (108.65 ± 20.94 FU/cm 2 ) ( p ‐value = 0.012). The average hair unit and the anagen rate showed slight increases from baseline to week 16, but these changes were not statistically significant. Subjective assessments indicated improvements in scalp oiliness and hair texture. The treatment was well tolerated, with only mild and transient adverse events reported. Conclusion Topical 5% phenytoin solution appears to be a safe and potentially effective therapeutic option for AGA.