What Is Male Pattern Baldness?
The most common form of male hair loss, explained — what causes it, the DHT mechanism, the Norwood scale stages, and how treatable it is.
Part of the Male Hair Loss Health Guide.
Key fact: Male pattern baldness — androgenetic alopecia — accounts for around 95% of male hair loss and affects about 66% of men by age 35. It is driven by genetics and the hormone DHT, and it is one of the most treatable hair loss conditions, especially when addressed early.
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Order Finasteride →What is male pattern baldness?
Male pattern baldness — medically termed androgenetic alopecia — is the most common form of hair loss in men, accounting for around 95% of cases. It follows a characteristic, progressive pattern and is caused by the interaction of genetic factors and the hormone dihydrotestosterone (DHT).
Despite being so prevalent, it remains a source of real concern for many men. The good news is that it is also one of the most treatable hair loss conditions, particularly when addressed early. Around 66% of men are affected by age 35, rising to over 85% by 50 — yet many delay seeking treatment, which reduces the window of maximum effectiveness.
95%
Of male hair loss is androgenetic alopecia
66%
Of men affected by age 35
85%
Of men affected by age 50
What causes male pattern baldness?
Male pattern baldness is driven by two interacting factors: genetics and hormones. The genetic component is inherited from both sides of the family — contrary to the common belief that hair loss only comes from your mother's side. It is polygenic, meaning multiple genes contribute, which is why patterns vary so much even within families.
Having a father or maternal grandfather with significant hair loss meaningfully increases your risk. But the absence of a strong family history does not guarantee you will be unaffected. For the full picture of genetic and non-genetic causes, see our guide on what causes hair loss in men.
Genetics
Inherited from both sides of the family. Polygenic — multiple genes determine susceptibility and pattern.
DHT sensitivity
Genetically determined sensitivity of scalp follicles to DHT. The same DHT level affects men very differently.
Age
The process can begin in susceptible men as early as their teens, and probability increases with age.
Hormonal status
Testosterone levels influence DHT production; other hormonal conditions can compound genetic loss.
The role of DHT
Dihydrotestosterone (DHT) is a potent androgen formed when the enzyme 5-alpha reductase converts testosterone. In men with a genetic predisposition, scalp follicles have receptors that are highly sensitive to DHT. When DHT binds to them, it disrupts the normal hair growth cycle:
- The anagen (growth) phase shortens — each hair grows for less time before shedding
- The follicle gradually miniaturises — producing progressively thinner, shorter, lighter hairs
- Eventually the follicle becomes dormant and stops producing hair altogether
This is why finasteride is so effective: it inhibits 5-alpha reductase, reducing scalp DHT by up to 70% and halting the miniaturisation process, giving surviving follicles a chance to recover.
The Norwood scale: stages of male pattern baldness
The Hamilton-Norwood scale is the standard system for describing how far male pattern baldness has progressed, from minimal recession to extensive baldness. Your stage closely predicts how well treatment will work, because medication can only help follicles that are still active:
| Norwood type | Description | Finasteride suitability |
|---|---|---|
| Type 1 | No significant recession — a mature hairline without loss | Preventive use possible |
| Type 2 | Slight temple recession; early vertex thinning | Ideal — early intervention |
| Type 3 | Pronounced recession forming an M, W or U shape | Highly suitable |
| Type 4 | Significant frontal and crown thinning, bridge between | Suitable — good results typical |
| Type 5 | Frontal and crown areas beginning to merge | Suitable — results more variable |
| Type 6 | Frontal and crown merged into extensive baldness | Limited response on bald areas |
| Type 7 | Most severe — only a horseshoe of hair remaining | Limited benefit to bald areas |
For a full walk-through of each stage and what it means for your treatment, see our dedicated Norwood scale guide.
Symptoms and early signs
Male pattern baldness develops gradually. The earliest signs to watch for include:
- A hairline receding at the temples — the "widow's peak" or M-shape recession
- Increasing visibility of the scalp at the crown when viewed from above
- Hairs becoming progressively finer, shorter and lighter in colour
- Increased shedding noticeable on pillows, in the shower or on clothing
- A change in how your hair fills your usual hairstyle
If you notice any of these, it is worth acting promptly — finasteride is most effective before significant follicle miniaturisation has occurred. Our finasteride suitability guide explains how your stage affects the likely result.
The emotional impact of hair loss
Many men find hair loss affects their confidence, self-image and emotional wellbeing — sometimes significantly. Research consistently shows that androgenetic alopecia can affect quality of life and social confidence, and in some cases contribute to low mood. These feelings are entirely valid and should not be minimised.
Seeking treatment is a practical, positive response. Many men report that taking action — through medication, lifestyle changes, or both — substantially improves how they feel about their hair and themselves. There is no need to simply "accept" hair loss when effective, well-evidenced treatments exist.
Can male pattern baldness be treated?
Yes — and the evidence for the two first-line, MHRA-approved options is strong:
- Finasteride 1mg daily — a prescription oral tablet that blocks DHT, with an 85% improvement rate over five years. Suitable for Norwood Types 2–5.
- Minoxidil 5% — an over-the-counter topical, applied twice daily, most effective combined with finasteride.
For a detailed comparison including hair transplants and laser therapy, read our complete male balding treatment guide.
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Order Finasteride →Frequently Asked Questions
What is male pattern baldness?
Male pattern baldness (androgenetic alopecia) is the most common form of hair loss in men, caused by a genetic sensitivity to DHT. It follows a recognisable pattern of hairline recession and crown thinning, classified by the Norwood scale, and affects around 66% of men by age 35.
Is male pattern baldness hereditary?
Yes — male pattern baldness is strongly genetic, inherited from both sides of the family. It is polygenic, meaning multiple genes contribute. Having a father or maternal grandfather with significant hair loss substantially increases your own risk, but absence of family history does not guarantee immunity.
What is the Norwood scale?
The Norwood (Hamilton-Norwood) scale is the standard classification for male pattern baldness, rating hair loss from Type 1 (no significant recession) to Type 7 (extensive baldness). It helps prescribers assess severity and recommend the most appropriate treatment at each stage.
Can male pattern baldness be stopped?
Yes — finasteride significantly slows or stops progression by reducing scalp DHT levels by up to 70%, with 85% of men showing improvement over five years. Early treatment at Norwood Types 2 to 4 yields the best results, as most follicles are still active at that point.
At what age does male pattern baldness typically start?
It can begin as early as the late teens. Around 25% of men with hereditary hair loss show signs before age 21. By 35, approximately 66% of men are affected; by 50, over 85%. The earlier it starts, the more important it is to seek treatment promptly.
References
- Norwood OT. Male pattern baldness: classification and incidence. Southern Medical Journal. 1975;68(11):1359–65. pubmed.ncbi.nlm.nih.gov
- Cranwell W, Sinclair R. Male Androgenetic Alopecia. Endotext. 2016. ncbi.nlm.nih.gov
- NICE Clinical Knowledge Summaries. Alopecia — androgenetic. cks.nice.org.uk
- NHS. Hair loss. nhs.uk
Medical disclaimer: This article is for informational purposes only and does not constitute medical advice. Always consult a qualified healthcare professional for diagnosis and treatment. In a medical emergency, call 999.