DHT, or dihydrotestosterone, is the hormone most directly responsible for pattern hair loss in both men and women. Your body converts roughly 10% of its testosterone into DHT each day through an enzyme called 5-alpha reductase. While DHT plays important roles during development, it can gradually shrink hair follicles on the scalp over time, leading to thinner strands and eventual hair loss.
How Your Body Makes DHT
DHT is an androgen, a type of sex hormone involved in male sexual development. It starts as regular testosterone circulating in your blood. When testosterone encounters the enzyme 5-alpha reductase (found in the skin, hair follicles, and prostate), it gets converted into DHT, a more potent form of the hormone. In men, this conversion happens primarily in the genital skin and prostate. In women, it takes place in the skin.
DHT is essential during fetal development and puberty. It drives the formation of male sex organs before birth and triggers changes like facial hair growth and voice deepening during adolescence. The problem isn’t DHT itself. It’s what happens when DHT interacts with hair follicles on certain parts of the scalp.
Why DHT Shrinks Hair Follicles
Hair follicles contain androgen receptors, proteins that bind to hormones like DHT and trigger a response inside the cell. When DHT attaches to a receptor on a scalp follicle, it can shorten the hair’s growth phase and cause the follicle to miniaturize. Over successive growth cycles, the follicle produces thinner, shorter, lighter hairs until it eventually stops producing visible hair altogether. This process is called miniaturization, and it’s the core mechanism behind pattern hair loss.
Here’s the part that surprises most people: the amount of DHT in your blood isn’t necessarily what determines whether you lose hair. Genetics play a bigger role. Variations in the AR gene, which codes for androgen receptors, can make those receptors more sensitive to DHT than normal. Someone with highly sensitive androgen receptors may experience significant thinning even with average DHT levels, while someone with less sensitive receptors could have higher DHT and keep a full head of hair. This is why two people with similar hormone profiles can have dramatically different hair outcomes.
The AR gene sits on the X chromosome, which is why hair loss patterns often (though not always) track through the maternal side of the family.
Pattern Hair Loss in Men vs. Women
In men, DHT-driven hair loss typically follows a recognizable pattern: a receding hairline at the temples and thinning at the crown, eventually progressing to more widespread loss. This is androgenetic alopecia, and it affects a majority of men to some degree by middle age.
In women, the picture is less clear. Scientists aren’t entirely sure how large a role DHT plays in female hair thinning. Women do convert testosterone to DHT in the skin, but their overall androgen levels are much lower. Female pattern hair loss tends to show up as diffuse thinning along the part line rather than a receding hairline, and the frontal hairline usually stays intact.
One situation where DHT clearly affects women is polycystic ovarian syndrome (PCOS), a hormonal condition where the ovaries produce excess androgens, including testosterone. The resulting increase in DHT can cause hair thinning on the scalp alongside other symptoms like excessive body hair growth, acne, and irregular periods. Women experiencing unexplained thinning, especially alongside those other symptoms, may benefit from hormone testing.
Treatments That Reduce DHT
Since DHT is the primary driver of pattern hair loss, the most effective treatments work by either blocking its production or reducing its effect on follicles. Two main pharmaceutical approaches exist, both targeting the 5-alpha reductase enzyme that converts testosterone into DHT.
Oral finasteride is the most widely studied option. It reduces scalp DHT levels by roughly 50% at standard doses. Topical finasteride, applied directly to the scalp, has shown even greater local reduction. One study found a 70% decrease in scalp DHT from a once-daily topical application. The topical route is appealing because it concentrates the effect where it’s needed while potentially reducing whole-body exposure to the drug.
Both forms work by slowing miniaturization and, in many cases, partially reversing it. Results typically take three to six months to become visible, and the effect only lasts as long as you continue treatment. Stopping allows DHT levels to return to baseline, and hair loss resumes.
Minoxidil, the other common hair loss treatment, works through a completely different mechanism. It increases blood flow to follicles and extends the growth phase of hair, but it doesn’t affect DHT at all. Many people use both approaches together.
Natural DHT Blockers
Saw palmetto is the most popular natural option. An extract from its berries may inhibit 5-alpha reductase, the same enzyme targeted by prescription treatments. The evidence is modest compared to pharmaceutical options. One small study of 25 participants found that a topical formulation containing saw palmetto increased hair count by about 12% after four months. That’s a meaningful change, but the study was small and used saw palmetto in combination with other ingredients, making it hard to isolate the effect.
Other natural compounds sometimes marketed as DHT blockers include pumpkin seed oil, green tea extract, and stinging nettle. The research on these is preliminary, and none have the level of clinical evidence behind them that finasteride does.
Side Effects of Lowering DHT
Because DHT is a potent androgen with roles throughout the body, reducing it systemically can cause side effects beyond the scalp. The most commonly reported issues with oral finasteride in men include reduced libido, difficulty with erections, and decreased semen volume. These affect a small percentage of users and typically resolve after stopping the medication, though a subset of men report persistent symptoms.
This is one reason topical formulations have gained popularity. By delivering the active ingredient directly to the scalp, they aim to lower DHT locally without suppressing it throughout the body as aggressively. The trade-off is that some systemic absorption still occurs with topical application, just at lower levels.
Women of childbearing age generally cannot use finasteride because DHT is critical for fetal development. Blocking it during pregnancy can cause serious birth defects in male fetuses.
The Role of Genetics in Your Options
Understanding that hair loss is driven by receptor sensitivity, not just DHT levels, changes how you think about treatment. If your androgen receptors are genetically programmed to be highly reactive, even a moderate reduction in DHT can make a real difference because you’re pulling the hormone below the threshold where your particular receptors respond aggressively. On the other hand, someone with less sensitive receptors may never need intervention at all.
There’s no widely available consumer test that precisely measures your androgen receptor sensitivity, but family history remains the strongest predictor. If multiple close relatives experienced significant pattern hair loss, the odds are higher that your follicles carry the more sensitive receptor variant. Starting treatment earlier, before extensive miniaturization has occurred, tends to produce better outcomes because it’s easier to maintain existing follicles than to revive ones that have already shut down.