Androgenetic alopecia is the medical name for pattern hair loss, the most common cause of thinning hair in both men and women. It is driven by a combination of genetics and the hormone DHT, which gradually shrinks genetically sensitive follicles until they produce finer hairs and eventually stop. In men it shows up as a receding hairline and crown thinning; in women, as diffuse thinning across the top of the scalp. The encouraging part: while you cannot change your genes, you can often slow or improve it, especially when you act early. At True Roots in La Canada Flintridge, evaluation is physician-led by board-certified Dr. Luis Valle.
What is androgenetic alopecia?
Androgenetic alopecia ("andro" for hormones, "genetic" for inheritance) is hair loss that follows a predictable pattern driven by your genes and your hormones. It is by far the most common type of hair loss, affecting a large share of men and women over their lifetimes. Unlike sudden shedding from stress or illness, it is gradual and progressive, which is why it often goes unnoticed until a noticeable amount of density is already gone.
What is DHT and how does it cause hair loss?
The central player is DHT (dihydrotestosterone), a hormone your body makes from testosterone via an enzyme called 5-alpha reductase. In people who are genetically sensitive to it, DHT binds to receptors on scalp follicles and slowly shrinks them, a process called miniaturization. With each growth cycle the follicle produces a thinner, shorter, weaker hair, until eventually it stops producing visible hair at all.
A key detail: the follicles on the back and sides of the scalp are usually resistant to DHT. That is why those areas keep hair the longest, and why they serve as the donor sites in hair transplants.
Is hair loss really genetic?
Androgenetic alopecia is largely genetic, and you can inherit the underlying DHT sensitivity from either side of your family, not only your mother's. Genetics set your predisposition, while hormones and age determine how quickly and how far it progresses. It is worth distinguishing this from other causes: stress-related shedding, thyroid issues, and nutritional deficiencies are not genetic and often reversible. If you are unsure which you have, see what is causing my hair loss.
How it looks in men versus women
The same condition presents differently by sex:
- Men: A receding hairline (often an "M" shape) and thinning at the crown, progressing along the Norwood scale.
- Women: Diffuse thinning across the top of the scalp and a widening part, staged on the Sinclair scale, rarely progressing to complete baldness. See hair loss in women.
Hormonal shifts, particularly around menopause for women, can make the pattern more apparent.
Can you stop genetic hair loss?
You cannot rewrite your genetics, but you can meaningfully slow androgenetic alopecia and often improve it, especially in the early to middle stages while follicles are still alive. Treatments work along a few different mechanisms:
- Lowering DHT: medications like finasteride address the hormonal driver. See FoLix vs. finasteride and minoxidil.
- Stimulating follicles: the FDA-cleared FoLix laser stimulates miniaturizing but still-living follicles without drugs or surgery.
- Prolonging growth: minoxidil extends the active growth phase.
The common thread is that all of them work best while living follicles remain, which is why early action matters so much. Once a follicle is gone, only a transplant can place hair there.
When to get evaluated
Because androgenetic alopecia is progressive, the best time to evaluate it is when you first notice consistent thinning, a receding hairline, or a widening part. An evaluation can confirm the pattern, rule out other contributing causes with bloodwork, and identify which treatments fit your stage. To understand candidacy for the laser option, see are you a good FoLix candidate.
This article is educational and not a substitute for personalized medical advice.