Minoxidil and finasteride are the two most evidence-based pharmacological treatments for androgenetic hair loss. They are frequently discussed together, but they work through entirely different mechanisms and their indications, side effect profiles, and appropriate use differ significantly.
Finasteride works on the root cause of androgenetic hair loss. It inhibits 5-alpha reductase, the enzyme that converts testosterone to dihydrotestosterone (DHT). DHT is the primary driver of follicle miniaturisation in genetically susceptible follicles. By reducing DHT by approximately 70%, finasteride slows or halts the miniaturisation process. The result is stabilisation in most patients and some regrowth in many. It is taken as a daily oral tablet (1mg dose for hair loss) or as a topical formulation.
Minoxidil works differently — it is a vasodilator that increases blood flow to the scalp and extends the anagen growth phase of the follicle. It does not address DHT. The result is stimulation of existing follicles to grow more actively, producing visible density improvement in many patients. It is available as a topical solution or foam (2% or 5%) or as a low-dose oral formulation.
Used together, the two treatments are complementary. Finasteride addresses the cause (DHT), while minoxidil stimulates what remains. The combination has a stronger evidence base for maintaining and improving density than either treatment alone.
Finasteride is approved for men only in the UK. Minoxidil is approved for both men and women. The potential side effects of finasteride — sexual dysfunction, mood changes in a small proportion of users — should be discussed in full before starting. Topical finasteride has a significantly lower systemic absorption and is associated with lower rates of systemic side effects.
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