What Is DHT (Dihydrotestosterone) and How Does It Cause Hair Loss?

Key Takeaways

Dihydrotestosterone (DHT) is a potent androgen formed when the 5-alpha reductase enzyme converts roughly 10% of circulating testosterone each day.
Paradoxically, DHT stimulates thicker beard and chest hair while shrinking scalp follicles at the temples and crown in genetically susceptible men.
Male pattern baldness is driven primarily by inherited androgen-receptor sensitivity inside scalp dermal papillae rather than ‘abnormally high’ testosterone.
5-alpha reductase inhibitors — finasteride (~70% DHT reduction) and dutasteride (>90% reduction) — shield sensitive follicles so miniaturized hairs can recover.

If you’ve ever researched receding hairlines or thinning crowns, three letters appear everywhere: DHT. Understanding what dihydrotestosterone actually does in adult male physiology explains both why pattern baldness happens and why targeted DHT blockers stop it without lowering testosterone.

Where DHT Comes From — and Its Paradoxical Role

Each day, an enzyme called 5-alpha reductase (found in scalp oil glands, hair follicles, skin, and prostate tissue) converts roughly 10% of circulating testosterone into DHT — an androgen that binds androgen receptors up to five times more tightly than testosterone itself.

During puberty, DHT is essential for voice deepening, facial and body hair development, and male reproductive growth. In adulthood, however, DHT acts as a biological paradox: it stimulates hair follicles on the beard and chest, yet shrinks genetically sensitive follicles on top of the scalp.

Step-by-Step: Follicular Miniaturization

DHT binds androgen receptors inside genetically sensitive temple, mid-scalp, and vertex dermal papilla cells (while follicles on the back and sides of the head lack this sensitivity — which is why a horseshoe fringe persists even in advanced baldness).
Anagen (growth) shrinks from several years down to mere months.
Shaft diameter narrows with each cycle, turning thick terminal hairs into wispy, translucent vellus strands until the follicle eventually goes dormant.

How Proven Treatments Protect DHT-Sensitive Follicles

Oral or topical Finasteride: Inhibits Type II 5-alpha reductase, cutting scalp and serum DHT by ~70% while leaving circulating testosterone intact (or slightly higher).
Dutasteride (off-label): Inhibits both Type I and Type II 5-alpha reductase for >90% DHT suppression when stronger stabilization is needed.
Minoxidil (complement): Works independently of DHT to widen follicular microcirculation and prolong anagen growth — making combined DHT blockade + minoxidil the gold-standard synergy.

References

Society for Endocrinology. Dihydrotestosterone — Hormone Physiology Overview. 2023.
American Academy of Dermatology. Male pattern hair loss (androgenetic alopecia). 2024.

Medical Editorial Review: Reviewed by the Amble Clinical Editorial Team. This article is for educational purposes only and does not replace an individualized consultation with a licensed healthcare professional.