Minoxidil Works on Existing Hair Follicles, Not New Ones
Minoxidil does not create new hair follicles but rather acts on existing miniaturized follicles to enlarge them and prolong their growth phase. The drug works by reversing the miniaturization process that occurs in androgenetic alopecia, transforming smaller, thinner follicles back into larger, terminal hair-producing structures 1.
Mechanism of Action on Existing Follicles
Minoxidil enlarges existing miniaturized hair follicles rather than generating new ones—morphometric studies have shown no evidence of follicular neogenesis (new follicle formation) in any patient treated with topical minoxidil 1.
The drug shortens the telogen (resting) phase and accelerates the transition to anagen (growth) phase, causing existing follicles to prematurely enter their growth cycle 2.
Minoxidil increases hair follicle size by acting on the dermal papilla, the specialized mesenchymal cells that control hair matrix cell growth and differentiation 1.
The mechanism likely involves calcium influx that upregulates ATP synthase, which promotes stem cell differentiation in the bulge region of existing follicles, allowing them to re-enter the anagen phase 3.
Clinical Implications
The primary morphologic change in androgenetic alopecia is miniaturization of terminal hair follicles—minoxidil reverses this by enlarging these shrunken follicles back to normal size 1.
Patients experience an initial shedding phase because minoxidil synchronizes the hair cycle, causing telogen hairs to shed before being replaced by thicker hairs in a new anagen phase 4.
Hair regrowth requires 6-12 months for visible improvement, as the drug must work through multiple hair cycles to progressively enlarge miniaturized follicles 5.
Treatment Requirements
Continuous application is mandatory—measurable changes disappear within months after discontinuation because the underlying miniaturization process resumes once treatment stops 5, 4.
The American Academy of Dermatology recommends topical minoxidil 5% applied twice daily as first-line therapy for androgenetic alopecia 5.
Combining minoxidil with PRP increases hair density by 1.74 times compared to minoxidil alone, providing enhanced enlargement of existing follicles 5, 6.
Common Pitfall to Avoid
- Do not expect new follicles to form—patients with completely bald areas (where follicles have been lost entirely) will not respond, as minoxidil can only work on follicles that still exist, even if severely miniaturized 1.