Written by Christina Boman-Markaki, reviewed by the Find Care Compare team · Last updated September 2026
Male pattern baldness, also known as androgenetic alopecia, is the most common type of hair loss in men. According to the NHS, it affects around 6.5 million men in the UK and usually develops gradually over time.
It happens when hair follicles that are genetically sensitive to a hormone called DHT become smaller, leading to thinner hair and, eventually, hair loss. Because genetics play a major role, it can affect each man differently and may start as early as the late teens or twenties.
This guide explains what male pattern baldness is, why it happens, the earliest signs to watch for and what its stages look like, so you know what you're dealing with before deciding on next steps.
What is male pattern baldness?
Male pattern baldness is a hereditary condition in which hair follicles on the scalp gradually shrink, or "miniaturise", over time. Each affected follicle produces progressively finer, shorter and less pigmented hairs until, in some cases, it stops producing visible hair altogether.
Unlike hair loss caused by stress, illness or nutritional deficiency, male pattern baldness follows a predictable pattern rather than diffuse, all-over thinning. It typically starts at the hairline and crown and spreads from there, which is why doctors and trichologists can "stage" it using a standard scale, covered below.
By age 50, around half of men show some degree of male pattern baldness, and the figure is higher by 60. It is not harmful to your physical health, but it can affect confidence and self-image, and many men look for ways to slow, stop or manage it.
What causes male pattern baldness?
Male pattern baldness comes down to three things working together: genetics, hormones and age.
- Genetics. Your likelihood of developing male pattern baldness, and how early it starts, is inherited. Contrary to the old idea that baldness only comes from your mother's side, susceptibility genes can be passed down from either parent, and researchers have identified hundreds of genetic regions linked to the condition. That is why hair loss patterns can vary widely even between brothers.
- Dihydrotestosterone (DHT). DHT is a hormone that your body makes from testosterone. In men whose follicles are sensitive to DHT, the hormone gradually shrinks scalp follicles, shortening the hair's growing phase and thinning each strand with every cycle. This is why treatments such as finasteride work by reducing DHT rather than testosterone itself. Having male pattern baldness does not mean you have unusually high testosterone or DHT, it means your follicles are more sensitive to it.
- Age. Follicle sensitivity to DHT builds up over time, so hair loss typically becomes more noticeable with age. It can start as early as the late teens, though for most men the process becomes more visible through their twenties, thirties and forties.
Early signs of male pattern baldness
Because male pattern baldness develops gradually, the early signs are often easy to miss or put down to normal shedding. Common early signs include:
- A receding hairline, particularly at the temples, creating an "M" or "V" shape
- Thinning at the crown or vertex (the top-back of the head), sometimes noticed first by other people or in photos taken from above
- A widening parting, or hair that looks gradually thinner when brushed or styled
- Finer, shorter or "wispy" hairs replacing thicker ones in affected areas
- More visible scalp under bright light or when hair is wet
Male pattern baldness causes patterned thinning at the hairline and crown rather than sudden clumps of hair loss, all-over shedding, or bald patches with a defined, coin-shaped edge. Those patterns point towards different causes, such as stress or an autoimmune reaction, and are worth mentioning to a GP separately.
The stages of male pattern baldness: the Norwood-Hamilton scale
Doctors, trichologists and hair loss clinics commonly describe the extent of male pattern baldness using the Norwood-Hamilton scale, a seven-stage classification first developed in the 1950s and refined by Dr O'Tar Norwood in 1975. It is a useful shared reference point for tracking how hair loss is progressing.
| Stage | What it typically looks like |
|---|---|
| Stage I | Hairline intact, with no noticeable recession. |
| Stage II | Mild recession at the temples, sometimes described as a "mature" hairline rather than hair loss. |
| Stage III | Generally the first stage considered clinically significant hair loss, with deeper temple recession and, in some men, thinning at the crown as well. |
| Stage IV | More pronounced hairline recession with distinct crown thinning, separated by a band of hair across the top of the head. |
| Stage V | The areas of hairline recession and crown thinning grow larger, and the band of hair separating them narrows further. |
| Stage VI | The receding hairline and balding crown join together, leaving a horseshoe-shaped band of hair around the sides and back. |
| Stage VII | The most extensive stage, with only a thin strip of hair remaining around the sides and back of the head. |
Stages I to III are generally considered mild, IV to V moderate, and VI to VII advanced. Most treatments are more effective when started earlier, which is one reason it is worth getting an early assessment rather than waiting to see how things progress.
When to see a doctor about hair loss
Male pattern baldness is not a medical emergency, and for many men it is simply something to monitor and decide whether to treat. However, it is worth speaking to a GP or dermatologist if:
- Hair loss is sudden, patchy, or comes with scalp itching, redness or pain, which can point to a different underlying cause
- You are losing hair from areas outside the typical hairline and crown pattern, such as eyebrows, beard or body hair
- Hair loss is affecting your confidence, mood or daily life
- You are considering prescription treatment, such as finasteride, which requires a prescriber's assessment
A GP or dermatologist can confirm that androgenetic alopecia is the underlying cause, rule out other conditions, and talk through which treatment options, if any, suit you.
Frequently asked questions
Related guides
Sources
- NHS - Hair loss
- British Association of Dermatologists - Male pattern hair loss patient information leaflet
Last reviewed: September 2026. This page is intended for healthcare navigation and information purposes only and does not provide medical advice.