hairlossDHT (dihydrotestosterone) is the hormone at the centre of pattern hair loss. Understanding what it does makes it much easier to judge the treatments, and the marketing, built around it.
Key points
- DHT is made from testosterone by the enzyme 5-alpha-reductase.
- In genetically sensitive follicles, DHT causes miniaturisation: each new hair grows back thinner and shorter.
- Prescription 5-alpha-reductase inhibitors lower DHT and are a doctor's decision because of possible side effects.
- "DHT-blocker" shampoos and supplements have much weaker evidence than prescription treatments.
What DHT does to hair follicles
In androgenetic alopecia, follicles on the top and front of the scalp are genetically sensitive to androgens. DHT binds to receptors in those follicles and gradually shortens the growth phase, so hairs become finer, shorter and lighter until some stop producing visible hair (StatPearls). Follicles at the back and sides are usually resistant, which is why they are used as the donor area in hair transplants.
Is high DHT the problem?
Usually not. Most men with pattern hair loss have normal hormone levels. What differs is how sensitive their follicles are, which is largely inherited. That is why a blood test for DHT is rarely useful for diagnosing pattern hair loss.
Medicines that lower DHT
Finasteride reduces DHT by blocking type II 5-alpha-reductase and is one of the most studied hair-loss treatments for men (AAD). Dutasteride blocks both enzyme types and is sometimes prescribed off-label. Both can have side effects, including sexual side effects in a minority of men, and they are not for women who are or may become pregnant. Whether either is right for you is a conversation with a doctor or dermatologist.
What about DHT-blocker shampoos and supplements?
Shampoos sit on the scalp for a few minutes, which limits what they can do to hormones in the follicle. The ingredient with the most interesting data is ketoconazole, an antifungal: a small study found ketoconazole shampoo improved hair density in men with pattern hair loss (Pierard-Franchimont et al.). Saw palmetto and other plant extracts are marketed as natural DHT blockers, but the evidence is limited. See our saw palmetto overview and natural remedies guide.
Is blocking DHT bad for you?
DHT has jobs in the body, particularly during male development. Lowering it in adults is generally well tolerated, but not by everyone. That trade-off is exactly why these are prescription decisions made with a doctor who knows your history.
When to see a doctor or dermatologist
- Sudden or heavy shedding, or shedding lasting longer than about six months
- Bald patches, broken hairs, or loss of eyebrows or eyelashes
- Scalp pain, burning, redness or scaling
- Hair loss together with fatigue, weight changes you can't explain, or irregular periods
FAQ
Does DHT cause hair loss in women?
Androgens play a role in female pattern hair loss too, but the picture is more complex. See our female hair loss guide.
Can you reverse DHT hair loss?
Treatment can often stop or slow it and sometimes thicken miniaturised hairs. Follicles that have been inactive for years are less likely to recover.
Does exercise raise DHT and cause baldness?
There is no good evidence that normal exercise causes hair loss.
Have a question about your own hair? Ask Hairloss AI, browse the hair loss FAQ, or read more in Hairloss Labs.