This is an excellent article discussing the safety and effectiveness of oral minoxidil. “Systemic adverse effects were infrequent and only 1.7% of patients stopped the treatment due to adverse effects.”
This second article reviewed 10 published papers addressing oral minoxidil use for alopecia in men and women: https://pubmed.ncbi.nlm.nih.gov/32516434/
Results: Ten articles were included for review comprising a total 19,218 patients (215 women and 19,003 men). Oral minoxidil dose ranged from 0.25 to 5 mg daily to twice daily. The strongest evidence existed for androgenetic alopecia and alopecia areata (AA), with 61-100% and 18-82.4% of patients demonstrating objective clinical improvement. Successful treatment of female pattern hair loss, chronic telogen effluvium, monilethrix, and permanent chemotherapy-induced alopecia was also reported. The most common adverse effects with oral minoxidil included hypertrichosis and postural hypotension.
Conclusion: Oral minoxidil is a safe and successful treatment of androgenic alopecia and AA. In addition to its therapeutic benefits, practical advantages over topical minoxidil stem from improved patient compliance.
Dr. Rassman: In my opinion, oral minoxidil is a reasonable second line drug for those men who can not use finasteride