DHT Explained: Why Your Hair Is Falling Out

Dihydrotestosterone (DHT) is the hormone responsible for the most common type of hair loss — androgenetic alopecia (male-pattern and female-pattern hair loss). Understanding how DHT works demystifies your hair loss, explains why certain treatments work, and helps you make informed decisions about medical and surgical options.

What Is DHT?

DHT is a potent androgen (male sex hormone) derived from testosterone. The enzyme 5-alpha reductase converts testosterone to DHT in various tissues, including the scalp. DHT is essential during puberty (it drives beard growth, body hair development, and voice deepening) but becomes the enemy of scalp hair in genetically susceptible individuals.

How DHT Causes Hair Loss

In genetically susceptible follicles, DHT binds to androgen receptors and triggers a process called follicular miniaturization — the follicle progressively shrinks over successive growth cycles, producing thinner, shorter, less pigmented hair until eventually the follicle produces only a tiny vellus hair (peach fuzz) or stops producing visible hair entirely. This process takes years to decades, which is why hair loss is gradual.

The Genetic Component

Susceptibility to DHT-driven hair loss is genetic — inherited through a complex polygenic pattern (not a single gene). Your father's hair, your maternal grandfather's hair, and your broader family history all contribute to your risk. But genetics determines susceptibility, not certainty — identical twins can have different hair loss patterns based on environmental factors, stress, and health.

Blocking DHT

Finasteride: Blocks type II 5-alpha reductase, reducing serum DHT by approximately 70%. The most studied and effective oral medication for hair loss. Dutasteride: Blocks both type I and type II 5-alpha reductase, reducing DHT by approximately 90%. More effective than finasteride but with a higher side-effect profile. Topical finasteride: Applied directly to the scalp to reduce systemic absorption — gaining popularity as a lower-side-effect alternative. Natural DHT blockers: Saw palmetto, pumpkin seed oil — modest evidence for mild benefit; not a substitute for pharmaceutical DHT blockers in progressive hair loss.

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