Safety of low-dose oral minoxidil for hair loss: A multicenter study of 1404 patients.

BACKGROUND: The major concern regarding the use of low-dose oral minoxidil (LDOM) for the treatment of hair loss is the potential risk of systemic adverse effects. OBJECTIVE: To describe the safety of LDOM for the treatment of hair loss in a large cohort of patients. METHODS: Retrospective multicenter study of patients treated with LDOM for at least 3 months for any type of alopecia. RESULTS: A total of 1404 patients (943 women [67.2%] and 461 men [32.8%]) with a mean age of 43 years (range 8-86) were included. The dose of LDOM was titrated in 1065 patients, allowing the analysis of 2469 different cases. The most frequent adverse effect was hypertrichosis (15.1%), which led to treatment withdrawal in 14 patients (0.5%). Systemic adverse effects included lightheadedness (1.7%), fluid retention (1.3%), tachycardia (0.9%), headache (0.4%), periorbital edema (0.3%), and insomnia (0.2%), leading to drug discontinuation in 29 patients (1.2%). No life-threatening adverse effects were observed. LIMITATIONS: Retrospective design and lack of a control group. CONCLUSION: LDOM has a good safety profile as a treatment for hair loss. Systemic adverse effects were infrequent and only 1.7% of patients discontinued treatment owing to adverse effects.