Quick answer: Androgenetic alopecia (AGA) is genetic, hormone-driven hair loss, known in men as male pattern baldness. It happens when DHT, a hormone made from testosterone, gradually shrinks genetically sensitive follicles at the temples and crown. It's the most common cause of hair loss in both men and women. Treatment aims to slow DHT's effect and support the follicles: prescription options include finasteride and minoxidil, and the best-studied natural options are saw palmetto, pumpkin seed oil and rosemary oil. The earlier you start, the more hair you keep.
What is androgenetic alopecia?
Androgenetic alopecia, often shortened to AGA, is progressive, patterned hair loss caused by the combination of androgens (male hormones) and genetic sensitivity. In men it usually starts with recession at the temples or thinning at the crown. In women it more often shows as a widening part with the front hairline intact.
The defining feature is miniaturization: with each growth cycle, affected follicles get smaller and produce thinner, shorter, lighter hairs, until some stop producing visible hair at all (Lolli 2017).
What causes AGA?
Two things have to be present: DHT and genetic sensitivity.
- DHT. The enzyme 5α-reductase converts roughly 10% of your daily testosterone into dihydrotestosterone (DHT). In sensitive scalp follicles, DHT binds to androgen receptors and drives miniaturization.
- Genes. AGA is polygenic, meaning many genes contribute. The two strongest risk regions sit on the X chromosome (the AR/EDA2R locus, inherited from your mother) and on chromosome 20 (Lolli 2017). That's why it can come from either side of the family.
Follicles at the back and sides of the head are largely resistant to DHT, which is why they stay full even in advanced AGA. For the full biology, read DHT, Explained.
Signs of androgenetic alopecia
- Temples receding into an M shape
- Thinning or a visible spot at the crown
- Fine, wispy hairs along the hairline (miniaturized hairs)
- Hair that takes longer to grow out and feels thinner overall
- A family history of similar hair loss
AGA progresses gradually over years. Doctors grade it in men with the Norwood scale, from stage 1 (no recession) to stage 7 (a horseshoe of hair around the back and sides).
How common is AGA?
Very. In a community study of men aged 18 to 49, 16% of men aged 18 to 29 already had moderate to extensive hair loss, rising to 53% of men in their forties (Rhodes 1998). Starting to thin in your twenties is common, and early is the best time to act.
Is it AGA or something else?
| Type | What it looks like | Common causes |
|---|---|---|
| Androgenetic alopecia | Patterned: temples and crown in men, a widening part in women; sides and back stay full | DHT plus genetic sensitivity |
| Telogen effluvium | Sudden, diffuse shedding all over, often a few months after a trigger | Stress, illness, surgery, crash dieting, deficiencies |
| Alopecia areata | Smooth, round bald patches | Autoimmune; see a dermatologist |
If your hair loss is sudden or patchy, see a doctor before starting any treatment.
Treatment options for androgenetic alopecia
| Option | How it works | Access in Canada |
|---|---|---|
| Finasteride | Blocks 5α-reductase to lower DHT | Prescription |
| Minoxidil | Extends the growth phase; doesn't affect DHT | Over the counter |
| Saw palmetto | Natural DHT blocker; inhibits 5α-reductase | No prescription |
| Pumpkin seed oil | Natural DHT blocker | No prescription |
| Rosemary oil | Supports scalp circulation | No prescription |
| Hair transplant | Moves DHT-resistant follicles from the back of the head | Clinic procedure |
Concerned about finasteride? See finasteride side effects and finasteride alternatives.
Natural treatment for androgenetic alopecia
Three natural ingredients have been tested in men with AGA:
- Saw palmetto inhibits the enzyme that makes DHT. Across seven studies, it improved hair density in 83.3% of patients (Evron 2020).
- Pumpkin seed oil raised hair count by 40%, versus 10% on placebo, in a 24-week trial of 76 men with AGA (Cho 2014).
- Rosemary oil matched minoxidil 2% on hair count over six months in 100 men with AGA, with less scalp itching (Panahi 2015).
Natural DHT blockers work best in early to moderate AGA, roughly Norwood 1 to 3, while follicles are still active. Read more in natural DHT blockers for hair loss.
Where DHT Defense fits
DHT Defense Hair Oil combines all three, saw palmetto, pumpkin seed oil and rosemary, with bhringraj in a light grapeseed base you apply straight to the scalp. Made in Toronto, no prescription, two minutes a day.
Frequently asked questions
What does AGA stand for in hair loss?
AGA stands for androgenetic alopecia: hair loss driven by androgens (DHT) in genetically sensitive follicles. In men it's also called male pattern baldness.
Is androgenetic alopecia genetic?
Yes. It's polygenic, with major risk genes on the X chromosome (from your mother) and chromosome 20, so it can run on either side of the family.
Can women get androgenetic alopecia?
Yes. In women it usually appears as thinning and a widening part rather than a receding hairline.
Is androgenetic alopecia reversible?
Follicles that are thinning but still active can often be thickened; areas bald for years rarely return. See is androgenetic alopecia reversible?
What is the best natural treatment for AGA?
Saw palmetto and pumpkin seed oil have the strongest human evidence as natural DHT blockers, and rosemary oil has a head-to-head result against minoxidil 2%.
Does androgenetic alopecia ever stop?
It tends to keep progressing with age, which is why treatment is ongoing rather than a one-time fix.
Related reading
- The Norwood scale: the 7 stages of male pattern hair loss
- How to stop a receding hairline early
- DHT, Explained: the full guide
References
- Lolli F, et al. Androgenetic alopecia: a review. Endocrine. 2017;57(1):9-17. PMID 28349362
- Rhodes T, et al. Prevalence of male pattern hair loss in 18-49 year old men. Dermatol Surg. 1998. PMID 9865198
- Evron E, et al. Saw palmetto, a systematic review in alopecia. Skin Appendage Disord. 2020. PMID 33313047
- Cho YH, et al. Effect of pumpkin seed oil on hair growth in men with androgenetic alopecia. Evid Based Complement Alternat Med. 2014. PMID 24864154
- Panahi Y, et al. Rosemary oil vs minoxidil 2% for the treatment of androgenetic alopecia. Skinmed. 2015. PMID 25842469