DHT (dihydrotestosterone) is a potent androgen that plays an important role in the biology of male androgenetic alopecia. However, not every form of hair loss is driven by DHT, and the role of androgens in female pattern hair loss is less uniform and less clearly defined than it is in men.
This guide explains how testosterone is converted to DHT, what the 5-alpha-reductase enzyme family does, why genetically susceptible hair follicles can progressively miniaturize, and where cosmetic scalp care fits without being confused with medical treatment.
What Is DHT?
DHT is an androgen formed when 5-alpha-reductase enzymes convert testosterone. It binds the androgen receptor with greater affinity than testosterone. DHT has normal physiological roles in several tissues, including male sexual development, the prostate and certain types of hair follicles.
Its effect on scalp hair depends on follicle location and genetic susceptibility. In male androgenetic alopecia, increased androgen signaling in susceptible frontal, mid-scalp and vertex follicles is associated with progressive thinning of hair shafts and follicular miniaturization. Occipital follicles are generally more resistant.
What Is 5-Alpha-Reductase?
5-alpha-reductase is an enzyme family that converts testosterone and other steroids into 5-alpha-reduced metabolites. Older explanations often focus only on type I and type II, but current classification includes a broader family with SRD5A1, SRD5A2 and SRD5A3.
- SRD5A1 (type I): expressed in multiple tissues including skin and scalp.
- SRD5A2 (type II): expressed in hair follicles and other androgen-sensitive tissues and strongly associated with male androgenetic alopecia.
- SRD5A3 (type III): has additional biological functions; its clinical role in androgenetic alopecia is less clearly established than that of type II.
It is therefore too simplistic to say that only one 5-alpha-reductase type matters in hair loss or that total DHT production alone determines whether a person develops androgenetic alopecia. Genetic predisposition, androgen-receptor signaling, local steroid metabolism and the biological sensitivity of the follicle all contribute.
How Does DHT Affect Follicles in Male Androgenetic Alopecia?
Male androgenetic alopecia is a multifactorial, polygenic condition. One of its best-supported mechanisms begins when DHT binds androgen receptors in genetically susceptible follicles.
Shortening of anagen: the active growth phase can progressively shorten, so successive hairs may grow for less time and become shorter and finer.
Follicular miniaturization: across repeated hair cycles, terminal hairs can become progressively thinner, shorter and less pigmented. This is a defining feature of male androgenetic alopecia.
The follicular microenvironment: inflammation, oxidative stress, extracellular-matrix changes and perifollicular fibrosis are also being studied in AGA. These findings should not be reduced to claims such as “DHT cuts off blood supply to the follicle,” which oversimplify the biology.
Is DHT the Cause of Every Type of Hair Loss?
No. DHT is especially relevant to male androgenetic alopecia. Telogen effluvium, alopecia areata, scarring alopecias, thyroid- or nutrition-related shedding and medication-associated hair loss can arise through different mechanisms.
Seeing hair shedding does not by itself prove that a person has high DHT. Pattern, distribution, onset and accompanying scalp or systemic findings are important in dermatological assessment.
Is the Role of DHT the Same in Female Pattern Hair Loss?
Not exactly. DHT and androgen-receptor signaling are strongly supported in male androgenetic alopecia, whereas female pattern hair loss is more biologically heterogeneous. Many women develop characteristic thinning without clear hyperandrogenism, and recent reviews note that the exact role of androgens in female pattern hair loss remains incompletely defined.
Diffuse thinning in women should therefore not automatically be attributed to excess DHT. Menopause, genetic susceptibility, endocrine factors, iron deficiency, thyroid disease and other potential causes may need to be considered according to the clinical picture.
Is DHT Produced Locally in the Scalp?
Yes. Skin and hair follicles express enzymes involved in steroid metabolism, so androgen biology is not determined solely by circulating hormone levels. Local DHT formation and androgen-receptor sensitivity are relevant to male androgenetic alopecia.
That does not mean that scalp DHT must be high whenever blood DHT is normal, nor does it mean that a topical product automatically reduces local DHT without systemic exposure. Even topical pharmaceutical agents can produce systemic exposure depending on the molecule and formulation.
Medical Treatments That Target the DHT Pathway
Agents that inhibit 5-alpha-reductase and reduce DHT signaling are medical treatments. Finasteride and dutasteride are examples of drugs acting on this pathway. Indications, regulatory approval, contraindications and adverse-effect considerations vary by country and by patient.
Minoxidil is not a 5-alpha-reductase inhibitor and does not work by directly lowering DHT. Treatment decisions for hair loss should follow appropriate medical assessment. Cosmetic products do not replace these medicines.
Does Zinc PCA Reduce DHT or Inhibit 5-Alpha-Reductase?
An important evidence distinction is needed here. Older laboratory studies reported that zinc sulfate and zinc ions could inhibit 5-alpha-reductase activity in human-skin assay systems. These were in-vitro findings and do not establish that Zinc PCA clinically reduces scalp DHT or treats androgenetic alopecia.
A more direct and defensible cosmetic role for Zinc PCA in Mirissa Lab formulas is scalp care and sebum-balance support, particularly for oil-prone scalps. Mirissa Lab products are therefore not positioned as “DHT blockers” or as 5-alpha-reductase treatments.
Are Niacinamide and Peptides DHT Treatments?
No. Niacinamide, Panthenol, Zinc PCA and cosmetic peptides can be used in formulas targeting scalp comfort, moisturization, sebum balance and the appearance of stronger or fuller-looking hair. Their presence in a formula does not prove that the finished product changes hormone levels or treats androgenetic alopecia.
Similarly, Acetyl Tetrapeptide-3 has preclinical extracellular-matrix data, but it has not been shown to increase collagen XVII or reverse DHT-related follicular miniaturization. Raw-material or complex data for Biotinoyl Tripeptide-1 should also not automatically be presented as proven clinical efficacy of a finished cosmetic serum.
Where Does Mirissa Lab Scalp Serum Fit?
Mirissa Lab Night Repair Hair Serum is a cosmetic scalp-care product designed to support the care of shedding-prone and weakened-looking hair. Its current formula includes Biotinoyl Tripeptide-1, Acetyl Tetrapeptide-3, Niacinamide, Zinc PCA, Panthenol, Squalane, Apigenin, Oleanolic Acid and other care ingredients.
This multi-active architecture focuses on scalp care and the appearance of stronger, fuller and well-cared-for hair. Without finished-product clinical evidence demonstrating DHT reduction, clinically meaningful 5-alpha-reductase inhibition or treatment of androgenetic alopecia, those claims should not be made.
Why Does Early Evaluation Matter?
Because androgenetic alopecia involves progressive miniaturization, early and accurate diagnosis can be useful when considering appropriate treatment options. However, it is not scientifically sound to describe a universal point at which a follicle becomes “fully fibrotic” and recovery suddenly becomes impossible.
Dermatological evaluation is appropriate when there is progressive recession of the hairline, clear vertex thinning, increasing variation in hair-shaft diameter or persistent hair loss.
Frequently Asked Questions
What is DHT?
DHT is a potent androgen formed from testosterone through 5-alpha-reductase enzymes. It plays an important role in male androgenetic alopecia.
How is DHT related to hair loss?
In genetically susceptible male scalp follicles, DHT-androgen-receptor signaling is associated with shortened anagen phases and progressive follicular miniaturization.
How many types of 5-alpha-reductase are there?
Current classification includes multiple family members, including SRD5A1, SRD5A2 and SRD5A3. Types I and II have been studied most extensively in androgen metabolism and male AGA, with type II strongly associated with the condition.
Does high DHT always cause hair loss?
No. Genetic and biological follicle sensitivity matters, and many types of hair loss are unrelated to the DHT pathway.
Is female pattern hair loss caused by DHT?
The role of androgens is less clearly defined than in male androgenetic alopecia. Female pattern hair loss is heterogeneous and can occur with normal androgen levels, so other causes may need evaluation.
Is Zinc PCA a DHT blocker?
Older in-vitro studies exist for zinc salts and zinc ions, but they do not prove that Zinc PCA clinically lowers scalp DHT. In Mirissa Lab formulas, Zinc PCA is positioned for scalp and sebum-balance care.
Does Mirissa Lab serum treat androgenetic alopecia?
No. Mirissa Lab serum is a cosmetic scalp-care product and does not replace medical AGA treatment. It is designed to support scalp care for shedding-prone hair and the appearance of stronger, fuller-looking hair.
Scientific References
- Androgenetic alopecia. Nature Reviews Disease Primers. 2025. PMID: 41068174.
- Male androgenetic alopecia. Anais Brasileiros de Dermatologia. 2025. PMID: 39809632.
- Androgenetic alopecia: An update. 2023. PMCID: PMC10562178.
- Antiandrogen therapy for the treatment of female pattern hair loss: A clinical review of current and emerging therapies. JAAD. 2025. PMID: 40345536.
- Androgenetic Alopecia in Women: A Narrative Review of Pathophysiology, Clinical Evaluation, and Treatments. 2026. PMID: 41714473.
- Inhibition of 5 alpha-reductase activity in human skin by zinc and azelaic acid. British Journal of Dermatology. 1988. PMID: 3207614.
This content is for informational purposes only and does not constitute medical advice. Mirissa Lab products are cosmetic care products and do not replace diagnosis or treatment of hair-loss disorders.
