Effect of oral minoxidil 1 mg and 2.5 mg on the growth speed of hair and nails

Background: Nail and hair growth are complex phenomena that are subject to individual variation and influenced by external factors. Objectives: To evaluate the effect of oral minoxidil on the growth rate of hair and nails. Materials & Methods: An open study was conducted involving 10 healthy adult men (21 to 46 years old), who under-went treatment with minoxidil 1 mg/day, followed by 2.5 mg/day for 14 days. Hair evaluation was conducted within 48 hours after shaving a standard retro auricular area. Nails were evaluated after 14 days, and the length between the thumbnail lunula and markings on the nail plate were measured. Hair and nail growth rate assessments were performed through dermoscopic photographs and measured in pixels using ImageJ software. Blood pressure and heart rate were evaluated during visits (D-14, D0, D14, and D28). Significance was set at p value <0.05, one-tailed. Results: Minoxidil 2.5 mg, but not 1 mg, increased nail growth speed by 50.7% (p<0.01). Minoxidil 1 mg and 2.5 mg increased hair growth speed by 16.5% and 35.9% (p<0.01), respectively. Heart rate increased by 9.7% and 16.7% with 1 mg and 2.5 mg (p<0.01), respectively, but there was no change in blood pressure (p>0.2), and other symptoms were not reported during the study. Conclusion: Oral minoxidil was well tolerated and increased nail and hair growth rates in healthy adult men.