Dihydrotestosterone, commonly abbreviated DHT, is the principal hormonal driver of androgenetic alopecia. Although DHT plays essential roles in normal physiology, including the development of male reproductive tissue, its interaction with genetically susceptible scalp follicles is the central mechanism behind progressive pattern hair loss.
This page explains what DHT is, how it affects hair follicles, why some follicles are vulnerable while others are not, and which treatments influence the DHT pathway.
What DHT is
DHT is an androgen, a class of steroid hormones that includes testosterone. It is produced when the enzyme 5-alpha reductase converts testosterone into dihydrotestosterone. DHT binds to androgen receptors with significantly higher affinity than testosterone itself, making it a more potent androgenic signal in tissues where it acts.
Two main isoforms of 5-alpha reductase exist:
- Type 1, expressed predominantly in skin, sebaceous glands, and some other tissues
- Type 2, expressed predominantly in genital skin, prostate, and hair follicles, particularly those of the scalp
The dominance of Type 2 in scalp follicles is what makes the hair follicle a primary site of DHT activity, and it is also why pharmacologic inhibition of 5-alpha reductase has therapeutic value in androgenetic alopecia.
Why DHT exists
Despite its association with hair loss, DHT is not pathological in itself. It serves important biological functions:
- Development of male reproductive anatomy in utero
- Maturation of secondary sexual characteristics during puberty
- Maintenance of certain androgen-dependent tissues in adulthood
The role DHT plays in androgenetic alopecia is not a malfunction of the hormone but an interaction between DHT and follicles that are genetically programmed to respond adversely to its presence.
How DHT affects hair follicles
In susceptible individuals, DHT binds to androgen receptors located on cells within hair follicle structures. This binding triggers a series of changes that progressively impair follicle function over many hair cycles. The cumulative effect is known as follicle miniaturization.
The specific changes include:
Shortened anagen phase
The hair growth cycle has three phases: anagen (active growth), catagen (transition), and telogen (rest). Anagen normally lasts 2 to 6 years for scalp hair. DHT exposure progressively shortens anagen, meaning each successive hair grows for less time before being shed.
Decreased follicle size
The dermal papilla, the cluster of cells at the base of the follicle that regulates growth, becomes smaller over time. The follicle as a whole shrinks, producing thinner, shorter hairs with each new cycle.
Changes in hair characteristics
Affected hairs become:
- Shorter
- Thinner in diameter
- Less pigmented
- More brittle and prone to breakage
Eventually, terminal hairs (the thick, pigmented hairs typical of an unaffected scalp) regress to vellus hairs (fine, short, lightly pigmented). At advanced stages, the follicle may stop producing visible hair entirely, although it often remains present in the skin.
Inflammatory contribution
Chronic DHT activity in scalp follicles is associated with low-grade perifollicular inflammation, which may further accelerate miniaturization in some individuals. This is one reason adjunctive treatments that reduce scalp inflammation, such as topical anti-inflammatory agents, are sometimes used alongside DHT-targeting therapies.
Why some follicles are vulnerable and others are not
A defining feature of androgenetic alopecia is its anatomical pattern. Follicles on the top, front, and crown of the scalp are typically affected, while those on the back and sides (the "horseshoe" area) generally remain stable throughout life.
This selective vulnerability reflects regional differences in:
- Androgen receptor density: higher on susceptible follicles
- 5-alpha reductase activity: greater in scalp regions prone to loss
- Local DHT concentration: elevated in affected areas
These differences are genetically determined. The DHT-resistant follicles on the back of the scalp are also why hair transplant procedures can produce lasting results when those follicles are surgically relocated to thinning regions.
DHT levels are usually normal
A common misconception is that androgenetic alopecia results from elevated systemic testosterone or DHT. In most affected individuals, circulating hormone levels are within the normal range. The condition is driven by local follicular sensitivity to DHT, not by hormone overproduction.
This is clinically important because:
- Routine testosterone testing is not informative for diagnosis
- Lifestyle interventions aimed at "lowering testosterone" do not address the underlying mechanism
- Treatment must target follicle response or local DHT activity, not systemic hormone levels in isolation
Treatment approaches that target DHT
Several clinically supported treatments work by reducing DHT activity at the follicle, by either inhibiting its production or blocking its receptor binding.
5-alpha reductase inhibitors
Finasteride is an oral medication that inhibits Type 2 5-alpha reductase. At the standard 1 mg daily dose, it reduces scalp DHT by approximately 60%. It is one of the most studied medications for male pattern hair loss and is appropriate for many men when medically suitable.
Dutasteride inhibits both Type 1 and Type 2 isoforms and produces greater overall DHT suppression, on the order of 90% reduction. It is used off-label for hair loss in some cases. The differences between these two medications are discussed in detail on our finasteride vs dutasteride page.
Topical anti-androgens
Some topical formulations include compounds intended to reduce local DHT activity at the scalp without systemic exposure. Topical finasteride is one example; it has shown promising data in clinical trials, though available evidence is more limited than for the oral form.
Spironolactone (women)
In women with androgenetic alopecia, spironolactone is sometimes used to block androgen receptors. It is not appropriate for use in pregnancy and requires medical supervision.
Minoxidil (does not target DHT)
Minoxidil, by contrast, does not affect DHT directly. It works downstream of the hormonal cascade by extending the anagen phase and supporting follicle activity. It is often used in combination with a DHT-targeting medication, because the two approaches address different parts of the same problem. This is discussed in our minoxidil vs finasteride comparison.
What this means for treatment decisions
Effective treatment of androgenetic alopecia generally requires addressing the DHT pathway in some form, because DHT activity is the underlying driver of the condition. Treatments that do not influence DHT or follicle activity have limited capacity to alter the long-term progression of the condition.
Decisions about whether to use a DHT-targeting medication, which agent to use, and what dose to take depend on multiple factors, including:
- Stage and rate of hair loss
- Age and reproductive considerations
- Existing medical conditions and concurrent medications
- Tolerance to potential side effects
- Personal preferences
These decisions are best made under physician supervision. Individuals considering treatment should expect a medical assessment, screening for contraindications, and ongoing follow-up to monitor response and tolerability.
How Curekey approaches DHT-targeted treatment
Curekey is a HIPAA-compliant telehealth platform that connects patients with licensed U.S. physicians experienced in managing androgenetic alopecia. Each case is reviewed individually, and prescription medications, including those that target the DHT pathway, are issued only when medically appropriate. Treatments are fulfilled by licensed pharmacies. More on the process is available on the how it works page.
Considering a structured assessment
If you are noticing pattern hair loss, an assessment by a physician can help determine whether DHT-targeted treatment is suitable for your case. A Curekey consultation includes a history review, photographic evaluation, and a treatment plan tailored to your medical profile.
