What Is Androgenetic Alopecia?

Androgenetic alopecia (AGA) — commonly called male-pattern or female-pattern hair loss — is a genetically influenced condition in which hair follicles progressively miniaturize in response to androgens (hormones like dihydrotestosterone, or DHT). It's the most common cause of hair loss worldwide, affecting people of all ethnicities and, to varying degrees, both sexes.

Despite its prevalence, AGA is widely misunderstood. It's not simply "going bald" — it's a biological process involving hormone sensitivity, genetics, and follicle biology that can begin as early as the late teens or early twenties.

The Role of DHT

DHT is derived from testosterone via the enzyme 5-alpha reductase. In people with a genetic predisposition, DHT binds to androgen receptors in hair follicles on the scalp, progressively shrinking them. Over multiple growth cycles, affected follicles produce shorter, thinner, and more lightly pigmented hairs until they may stop producing visible hair altogether.

Crucially, not all scalp follicles are equally sensitive to DHT. This is why hair loss in AGA follows predictable patterns — and why hair on the sides and back of the head (which lacks the same androgen sensitivity) is typically retained even in advanced cases.

Hair Loss Patterns

In Men

Male-pattern hair loss is typically classified using the Norwood-Hamilton Scale, ranging from Type I (minimal recession) to Type VII (only a horseshoe-shaped band of hair remains on the sides and back). The most common early signs include:

  • Recession at the temples
  • Thinning at the crown
  • Gradual merging of these two areas over time

In Women

Female-pattern hair loss more often presents as diffuse thinning across the top of the scalp rather than complete bald patches — the hairline at the front is usually maintained. It's classified using the Ludwig Scale (Types I–III). Hormonal events like menopause, pregnancy, and polycystic ovary syndrome (PCOS) can accelerate AGA in women.

Evidence-Based Treatment Options

There is no cure for AGA, but several treatments have demonstrated efficacy in clinical studies:

Minoxidil

The most widely used topical treatment, available over the counter in 2% and 5% formulations. Minoxidil prolongs the anagen (growth) phase and increases blood flow to follicles. It requires consistent, ongoing use — stopping treatment typically results in a return of hair loss. An oral low-dose formulation is increasingly used and may offer greater efficacy for some individuals.

Finasteride (Oral)

A prescription 5-alpha reductase inhibitor that reduces DHT levels systemically. Clinical trials show it slows hair loss and promotes regrowth in a meaningful proportion of men. It is not approved for use in premenopausal women due to risk of hormonal effects. Potential side effects should be discussed with a physician before starting.

Low-Level Laser Therapy (LLLT)

Devices using specific wavelengths of red light have FDA clearance for promoting hair growth. The mechanism is thought to involve stimulation of cellular energy production in follicles. Evidence quality varies, but some studies show modest benefits in both men and women.

Platelet-Rich Plasma (PRP)

PRP involves injecting concentrated growth factors from a patient's own blood into the scalp. Research results are mixed, and it's generally considered a complementary rather than standalone treatment. It's typically administered in clinical settings.

Lifestyle Factors That May Influence Progression

  • Chronic stress — elevated cortisol can accelerate shedding in genetically susceptible individuals
  • Nutritional deficiencies — low iron, vitamin D, or zinc are associated with increased hair shedding
  • Scalp health — chronic inflammation or buildup may exacerbate follicle miniaturization
  • Smoking — linked to reduced scalp circulation and accelerated hair loss in some research

When to See a Doctor

If you notice rapid or patchy hair loss, or if shedding begins suddenly rather than gradually, it's worth seeing a dermatologist or trichologist. Sudden diffuse shedding can indicate conditions unrelated to AGA — such as alopecia areata, thyroid dysfunction, or telogen effluvium — which require different approaches.

The Takeaway

Androgenetic alopecia is a complex, multifactorial condition — but it's not untreatable. Early intervention, evidence-based treatments, and a healthy scalp care routine offer the best chance of slowing progression and maintaining hair density over time. Understanding what's driving your hair loss is always the first and most important step.