Understanding Androgenetic Alopecia
Androgenetic alopecia is one of the most common types of hair loss worldwide. Hair follicle function declines gradually through a combination of genetic and hormonal factors. The goal of treatment is not to restore every lost hair, but to assess follicles that still have remaining function and determine a management approach. Early diagnosis and ongoing care are important.
Androgenetic alopecia (AGA) includes male pattern hair loss (MPHL) and female pattern hair loss (FPHL) (Devjani Shivali et al., 2023). Although they share the same biological mechanisms, their clinical presentations can differ considerably.
The Role of DHT and Follicle Miniaturization
Dihydrotestosterone (DHT) is the key mechanism. In scalp hair follicles, testosterone is converted to DHT through the action of 5α-reductase (an enzyme that converts testosterone to a more potent form). Type II 5α-reductase is primarily involved, though the Type I enzyme is also present in areas such as the sebaceous (oil) glands of the scalp and plays some role. When DHT binds to androgen receptors in follicle cells, the process of follicle miniaturization begins. Follicles that once produced thick, long hairs gradually shift to producing thinner, shorter, vellus-like (fine, downy) hairs.
This change progresses slowly over many years. In the early stages, it may feel like nothing more than hair becoming slightly thinner. A decrease in hair shaft diameter can occur long before any noticeable reduction in overall hair density.
Male pattern hair loss follows a pattern of a receding frontal hairline or thinning at the crown (Nestor Mark S et al., 2021). Female pattern hair loss often involves broad thinning centered on the crown while the hairline is preserved. The same hormonal mechanism can present differently depending on the hormonal environment.
The fact that follicles have not yet completely lost their function is the basis for considering treatment options. Even when function has declined, if living follicles remain, a treatment approach may be worth evaluating. Treatment response can vary from person to person. This is why it is important not to miss the window of opportunity.
Causes and Risk Factors for Androgenetic Alopecia
There is no single cause of hair loss. It arises from an interplay of genetic predisposition, hormonal changes, and environmental factors (Devjani Shivali et al., 2023).
Genetic Predisposition
There is a common saying that if your maternal grandfather was bald, you will be too — but this is only partly true. The genes associated with androgenetic alopecia are distributed across multiple chromosomes, not just the X chromosome. Risk is inherited from both the paternal and maternal sides. A father with significant hair loss may not pass it on to his children, and hair loss can still occur even when there is no history on the maternal side.
The Effect of Hormonal Changes
Hormonal changes can trigger genetic predisposition. After puberty, rising testosterone levels lead to higher DHT concentrations, and follicle miniaturization may begin at this point. After menopause, declining estrogen levels mean that androgens have a relatively greater influence, which is associated with a higher incidence of FPHL (Nestor Mark S et al., 2021). Postpartum hair loss can occur regardless of an AGA predisposition, but in those who have one, it may be more pronounced or last longer. Thyroid dysfunction can also cause or worsen hair loss through a separate mechanism.
Stress and Lifestyle Factors
Chronic stress is a risk factor that should not be overlooked. Animal studies have reported that cortisol may suppress hair follicle stem cell activity and shorten the anagen (growth) phase. Clinical evidence in humans remains limited. It has also been observed that, two to three months after a major stressor, a sudden surge of hair shedding can occur — this corresponds to stress-induced telogen effluvium (a condition where hair follicles prematurely shift into the resting/shedding phase). When AGA is also present, both processes may progress simultaneously.
Nutritional status matters. Deficiencies in iron, biotin, zinc, and vitamin D may make it more difficult for hair to grow. Excessive caloric restriction or insufficient protein intake can also weaken hair. Seborrheic dermatitis (a common scalp condition causing flaking and irritation) or scalp inflammation can place additional burden on follicles that are already compromised.
Ultimately, understanding the cause of hair loss requires examining how genetics, the current hormonal environment, and lifestyle factors are overlapping. This is why analyzing the cause before beginning treatment is important.
Stages of Hair Loss Progression and Diagnostic Criteria
When hair loss is suspected, it is important to objectively confirm the current stage. Relying on subjective impression alone can lead to missing the optimal treatment window or causing unnecessary anxiety.
Classification Systems
Clinically, male pattern hair loss is classified using the Hamilton–Norwood scale (Stages I–VII) and female pattern hair loss using the Ludwig scale (Stages I–III) (Nestor Mark S et al., 2021). The Hamilton–Norwood scale is based on the degree of frontal hairline recession and the extent of crown thinning, while the Ludwig scale assesses the reduction in hair density centered on the crown. These classifications serve as a practical basis for determining the direction of treatment.
Diagnostic Tools and Methods
Trichoscopy (hair dermoscopy — a technique that uses a magnifying device to examine the scalp and hair in detail) can be used to assess variability in hair shaft diameter, the presence of perifollicular inflammation, and other dermoscopic findings. It can help identify follicle miniaturization that is not visible to the naked eye. Quantifying the number of hairs per unit area using hair density measurement equipment is also useful for monitoring treatment progress over time.
Blood tests can also aid in diagnosis. For female pattern hair loss, a hormonal panel (testosterone, DHEAS, thyroid hormones) and nutritional markers (serum ferritin, vitamin D, zinc) are checked. If thyroid dysfunction, anemia, or nutritional deficiency is driving hair loss, correcting these issues first is important. It is recommended to review these results together with your physician.
The Importance of Early Diagnosis
Many patients first seek care when they have already reached Hamilton–Norwood Stage III–IV. Considering treatment at this stage is not without value, but the fewer viable follicles that remain, the more limited the potential range of treatment response may be. Rather than waiting until hair loss is visibly noticeable, it may be more appropriate to seek a diagnosis when hair begins to feel finer or when a change in thickness is first perceived.
Diagnostic findings serve as the basis for deciding whether to begin pharmacological treatment, whether to incorporate regenerative therapies, or whether hair transplantation is worth considering.
Treatment Options for Androgenetic Alopecia
Treatment for androgenetic alopecia is divided into pharmacological (drug-based) and regenerative approaches — these are not competing options. Combining them according to the stage of hair loss is a standard approach.
Pharmacological Treatment
Topical minoxidil is an FDA-approved treatment for hair loss (Gupta A K et al., 2022). The 5% formulation is used for male pattern hair loss; the FDA has approved the 2% solution and 5% foam for female pattern hair loss. As the 5% liquid formulation is primarily approved for use in men, it is important to confirm the approved indications and suitability for your sex and formulation with your physician. When applied directly to the scalp, it may be involved in prolonging the anagen (growth) phase through several mechanisms including vasodilation (widening of blood vessels), anti-inflammatory effects, and induction of the Wnt/β-catenin signaling pathway. Some individuals may experience a temporary increase in shedding in the early stages of application; this is sometimes interpreted as a resetting of the hair growth cycle. If symptoms persist or cause significant discomfort, consulting a healthcare professional is important.
Oral finasteride inhibits Type II 5α-reductase, thereby reducing DHT production (Nestor Mark S et al., 2021). It may help slow the progression of hair loss. Prescribing is restricted in patients of childbearing potential due to the risk of fetal malformations, and some sexual side effects have been reported in men, so adequate counseling is necessary.
Dutasteride inhibits both Type I and Type II 5α-reductase. It is reported to have a broader range of DHT suppression, but this does not mean it is more suitable in every case. Whether it is appropriate, along with its potential side effects, should be reviewed together with a physician.
Beyond FDA-approved treatments, low-level laser therapy (LLLT — a non-thermal light-based device cleared as an FDA 510(k) medical device) is also available. Oral and topical medications, hormonal therapy, nutritional supplements, and hair transplantation each fall within their respective pharmacological, adjunctive, or surgical treatment categories (Nestor Mark S et al., 2021). Low-dose oral minoxidil is also discussed as a treatment option, and its suitability should be confirmed in consultation with a physician. Treatment response and the pattern of side effects can vary from person to person.
Regenerative Treatments
When medications alone have limitations, regenerative therapies may be discussed as a complementary approach. PRP (platelet-rich plasma) treatment involves concentrating platelets from the patient's own blood and injecting them into the scalp. There are reports that the growth factors in platelets may be involved in regulating the environment around hair follicles.
Exosome-based therapy is being investigated on the premise that extracellular signaling molecules (substances released by cells that can influence other cells) may be able to interact with follicle regeneration pathways. Neither the Korean Ministry of Food and Drug Safety (MFDS) nor the FDA has granted formal approval for this approach in hair loss treatment; it remains at the research stage. Some small-scale pilot studies have suggested a response, but large-scale randomized controlled trials are lacking (Devjani Shivali et al., 2023). It has not been established as a standard treatment, and this approach should be considered with an awareness that the clinical evidence base is not yet sufficient.
PDRN (polydeoxyribonucleotide — a substance derived from salmon DNA that is being studied for its potential tissue-regenerative properties) is discussed as a substance that may be involved in scalp tissue regeneration and inflammation-related pathways. It may be considered alongside other treatments when chronic scalp inflammation is present, but whether it is applicable depends on diagnostic findings and individual condition. Response to regenerative treatments can vary from person to person.
Principles of Combination Treatment
The combination of treatments varies depending on the stage of hair loss, sex, overall health status, and lifestyle. In the early stages, starting with topical minoxidil alone is one option; when progression is rapid or the response to medication is insufficient, combining oral medications with regenerative therapies may be considered. The most appropriate combination is determined based on diagnostic findings.
What to Realistically Expect from Hair Loss Treatment
When starting hair loss treatment, the greatest hope is often that lost hair will grow back. To be honest, that is difficult to make the primary goal.
The realistic goal of androgenetic alopecia treatment is to maintain the function of follicles that are still living and, if possible, to hope for partial recovery. Follicles that have already completely lost function are difficult to restore with medication or regenerative treatments. Follicles that are still in the process of miniaturizing — meaning their function has declined but they have not completely ceased activity — are the candidates for a treatment approach to be evaluated. This is why early assessment matters.
Treatment Response Over Time
A minimum observation period of 3–6 months is needed to assess treatment response, because the hair growth cycle operates on a timescale of several months. Some individuals may notice a temporary increase in shedding after first using minoxidil. This is explained as a process in which resting-phase hairs shed before transitioning into the growth phase.
The Reality of Relapse After Stopping Treatment
When treatment is discontinued, the response that had been maintained may be lost (Devjani Shivali et al., 2023). Some studies have reported that in cases where hair density was maintained during medication use, hair loss may resume within a few months of stopping (Gupta A K et al., 2022). This also varies from person to person. Androgenetic alopecia treatment is not like a course of antibiotics that concludes after a set period. Consistent management is needed to maintain the treatment response. This is something that should be clearly understood before starting treatment.
The Limitations and Role of Hair Transplantation
Hair transplantation is a surgical procedure that fills in areas where hair has already been lost. The transplant itself does not block the effects of DHT. As a result, hair in untreated surrounding areas may continue to thin even after transplantation. For this reason, the use of pharmacological and regenerative treatments to manage the surviving follicles — including the transplanted hairs and the surrounding area — is generally reviewed alongside the procedure.
The Essence of Treatment
Hair loss treatment is not a one-time fix. If follicles that are still living are appropriately managed while they remain, treatment may help with managing the progression of hair loss depending on the individual's condition. Treatment response varies from person to person. Whatever treatment is chosen, that decision begins with accurately understanding the current state of your own follicles.
Frequently Asked Questions
What is the difference between androgenetic alopecia and ordinary hair loss?
Androgenetic alopecia is a chronic process in which DHT-driven follicle miniaturization progresses gradually over many years. What is commonly called "ordinary hair loss" — telogen effluvium — occurs when a temporary factor such as severe stress, nutritional deficiency, or childbirth causes a large number of actively growing hairs to shift simultaneously into the resting phase. Because telogen effluvium often resolves on its own once the triggering factor is addressed, its prognosis is distinct from androgenetic alopecia, which requires long-term management.
If I stop taking hair loss medication, will the hair loss come back?
Because the biological cause of androgenetic alopecia does not go away on its own, stopping medication may allow DHT's miniaturizing effect on follicles to resume, and hair loss may progress again. Since medication works by "maintaining" follicle function during the period of use, the decision about whether to continue treatment should be made together with a physician, taking into account your current hair condition and overall health.
Can women also develop androgenetic alopecia?
Female pattern hair loss (FPHL) falls within the category of androgenetic alopecia and involves the same DHT pathway as in men. However, women more commonly present with broad thinning centered on the crown while the hairline is preserved, which distinguishes it visually from male pattern hair loss. Cases in which symptoms become more pronounced after menopause — as declining estrogen levels allow androgens a relatively greater influence — have also been reported.
Will transplanted hair fall out again?
Donor follicles used in hair transplantation tend to have relatively higher resistance to DHT, and this characteristic is generally maintained after transplantation. However, a transplant itself does not stop the progression of androgenetic alopecia, so existing follicles outside the transplanted area may continue to be affected. For this reason, continuing pharmacological treatment after transplantation to manage the remaining follicles is generally recommended.
Is it better to start treatment early?
The earlier treatment is started — that is, while follicles are still in the process of miniaturizing and have not yet completely ceased function — the higher the hair density that may potentially be maintained. Because hair loss progresses over many years, the point at which you feel "I haven't lost that much yet" may actually be the window during which treatment response is most favorable. It is important to objectively confirm the stage of progression before deciding on the timing of treatment.
This content is intended for general medical information purposes only, and results may vary depending on individual circumstances. Please consult a specialist for accurate diagnosis and treatment.