Low-Dose Oral Minoxidil During Chemotherapy: A Review of the Mechanism and Current Evidence

Chemotherapy-induced alopecia (CIA) significantly impacts patients' quality of life. While low-dose oral minoxidil (LDOM) shows promise in treating CIA after chemotherapy completion, its safety and efficacy when given during active chemotherapy remain unclear. This review examines existing literature on CIA pathogenesis, minoxidil's mechanism of action, and LDOM efficacy to explore its potential use during chemotherapy. Recent retrospective studies demonstrated LDOM's good tolerability in cancer patients post-chemotherapy, with minimal adverse effects. Scalp cooling, the only Food and Drug Administration-cleared intervention to mitigate CIA, is thought to reduce chemotherapeutic delivery to the hair follicles, whereas minoxidil, a vasodilator, increases blood flow to the follicle. Despite these differing mechanisms, preclinical studies suggest potential benefits of LDOM during chemotherapy. One study demonstrated a protective effect of subcutaneous minoxidil against cytarabine-induced alopecia, while another showed faster regrowth with systemic minoxidil administered concurrently with paclitaxel. LDOM may therefore exert benefits through mechanisms beyond vasodilation, potentially by its impact on the hair cycle. Studies on topical minoxidil during chemotherapy show variable results, possibly due to poor adherence or variations in application practices—limitations LDOM could address. Given the psychological impact of CIA and limited treatments, investigation of LDOM's safety and efficacy when initiated during chemotherapy is warranted.