Male pattern baldness is a genetic condition in which hair follicles on the scalp gradually shrink in response to a hormone called dihydrotestosterone, or DHT. It follows a predictable pattern — typically a receding hairline and thinning at the crown — and it affects roughly half of men by age 50 and most men to some degree by age 70. The process is driven by inherited gene variants, not by stress, shampoo, or poor circulation.
What Actually Causes Male Pattern Baldness?
Male pattern baldness, also called androgenetic alopecia, is caused by a combination of genetics and hormones. Both have to be present for the condition to develop in its typical form.
The hormone involved is DHT, which the body makes from testosterone. An enzyme called 5-alpha-reductase converts testosterone into DHT in tissues including the scalp. DHT is far more potent than testosterone at the androgen receptor.
What makes male pattern baldness unusual is that DHT does not harm hair everywhere on the body. It actually promotes hair growth on the face, chest, and back. On certain areas of the scalp, though, hair follicles respond to DHT by gradually producing thinner, shorter hairs until the follicle stops producing visible hair altogether.
This is why the condition looks so specific. The follicles along the front hairline and on the crown tend to be the most sensitive to DHT. Follicles on the sides and back of the scalp are usually far less sensitive, which is why men with advanced baldness often keep a horseshoe-shaped band of hair.
How DHT Shrinks Hair Follicles Over Time
DHT does not kill hair follicles. It miniaturizes them.
Each hair follicle goes through a growth cycle. There is a long growing phase (anagen), a short transition phase, and a resting phase before the hair sheds. In men with the genetic predisposition, DHT binds to receptors inside susceptible follicle cells and shortens the growing phase over time.
The result is a follicle that produces a hair shaft that gets progressively thinner and shorter with each cycle. Eventually the follicle may produce only a fine, nearly invisible hair — or none at all. The follicle itself is still alive. This is an important distinction, because it explains why some treatments can partially restore hair if they are started early enough.
This miniaturization happens slowly. It typically unfolds over years, not weeks or months.
Which Genes Are Involved in Male Pattern Baldness?
The genetics are more complicated than the old idea that baldness comes only from your mother’s father.
The most well-studied genetic association is with the androgen receptor (AR) gene, which sits on the X chromosome. Because men inherit one X chromosome from their mother, this gene does pass down the maternal line. Variants in this gene can make hair follicles more sensitive to DHT.
But the AR gene is not the whole story. Research has identified many other genetic variants across the genome that are associated with male pattern baldness, including some on chromosomes inherited from either parent. This means a man can inherit the tendency from his father’s side as well.
Some studies suggest that having a father with male pattern baldness increases a man’s risk, but the inheritance is polygenic — meaning many genes each contribute a small effect. There is no single “baldness gene,” and no consumer genetic test can reliably predict whether or when a man will lose his hair.
What Are the Stages of Male Pattern Baldness?
Clinicians commonly describe male pattern baldness using the Norwood-Hamilton scale, which runs from Stage I to Stage VII. It is a descriptive tool, not a diagnostic test, and it was developed to standardize how hair loss is classified in research and clinical practice.
The general progression looks like this:
- Stage I: Little or no visible hair loss. The hairline may look mature but is not receding.
- Stage II: Mild recession at the temples, often described as a maturing hairline.
- Stage III: Deeper recession at the temples that forms a distinct M, U, or V shape. This is usually the first stage considered true baldness.
- Stage IV: Further recession plus noticeable thinning or a bald patch at the crown, with a band of hair separating the two areas.
- Stage V: The receding front and the crown thinning merge, with a narrower band of hair between them.
- Stage VI: The bridge of hair between the front and crown disappears, leaving a large bald area on top.
- Stage VII: The most advanced stage, with only a horseshoe-shaped band of hair remaining around the sides and back.
Not every man moves through every stage, and the pace varies widely. Some men stay at Stage II or III for decades. Others progress faster. The scale is a snapshot, not a forecast.
Is Male Pattern Baldness the Same as Other Types of Hair Loss?
No, and the difference matters.
Male pattern baldness has a distinct pattern and a distinct cause. Other forms of hair loss can look similar at first but have different drivers and different implications.
Telogen effluvium is a temporary shedding condition often triggered by illness, major stress, surgery, or nutritional deficiency. It usually causes diffuse thinning rather than patterned loss, and it often reverses once the trigger resolves. Alopecia areata is an autoimmune condition that causes smooth, round patches of hair loss and can affect any hair-bearing area. Scarring alopecias are a group of conditions in which inflammation destroys the follicle permanently.
If hair loss is patchy, sudden, accompanied by scalp pain, scaling, or itching, or occurs alongside other symptoms, that is not typical male pattern baldness. A dermatologist can usually distinguish these conditions with a physical exam, and sometimes a scalp biopsy. Getting the right diagnosis matters because the treatments are different.
Can Male Pattern Baldness Be Treated or Slowed?
Two medications are widely used and have the strongest evidence for treating male pattern baldness: finasteride and minoxidil.
Finasteride is an oral prescription drug that blocks the 5-alpha-reductase enzyme, lowering DHT levels in the scalp. Clinical trials have found it can slow hair loss and, in some men, regrow hair, with results typically taking several months to appear. It works best in men who still have active follicles. It is not approved for women of childbearing age, and it can cause sexual side effects in a minority of men.
Minoxidil is available over the counter as a topical liquid or foam. It prolongs the growth phase of the hair cycle and can slow loss and promote some regrowth. It does not work through DHT. Results also take months, and hair loss typically resumes if the treatment is stopped.
Other options exist, including low-level laser therapy, platelet-rich plasma injections, and hair transplant surgery. The evidence for laser therapy and PRP is more limited than for the two medications, and results vary. Hair transplant surgery can produce durable results by moving DHT-resistant follicles from the back of the scalp to thinning areas, but it does not stop ongoing loss in untreated areas.
Some clinicians also recommend ketoconazole shampoo, which has mild anti-androgen activity. The evidence for its effect on hair growth specifically is limited.
No treatment reliably restores a full head of hair once follicles have stopped producing visible hair. Starting treatment earlier generally produces better results, but no treatment works for everyone.
Does Anything Else Cause or Worsen Male Pattern Baldness?
Genetics and DHT are the core drivers. Other factors can influence how hair looks or feels, but they do not cause male pattern baldness.
Stress, poor diet, thyroid disorders, and low iron can contribute to hair shedding, but that is a different process. Smoking has been associated with earlier onset and faster progression of androgenetic alopecia in some studies, though the evidence is not definitive. There is no consistent evidence that wearing hats, washing hair frequently, or using certain shampoos causes or worsens male pattern baldness.
Testosterone levels themselves are not the main factor. Men with normal testosterone can still develop male pattern baldness if their follicles are genetically sensitive to DHT. This is why the condition is about follicle sensitivity, not hormone levels.
Frequently Asked Questions
Does male pattern baldness come from your mother’s side only?
No. The androgen receptor gene on the X chromosome does come from the mother, but many other genes on other chromosomes are also involved, and some are inherited from the father. Inheritance is polygenic, meaning many genes each contribute a small effect.
At what age does male pattern baldness usually start?
It can begin in a man’s late teens or early twenties, though many men first notice it in their thirties or forties. The timing and speed vary widely and are largely determined by genetics.
Can male pattern baldness be reversed?
It can sometimes be partially reversed with treatment, especially if started early, but complete reversal is uncommon. Once a follicle stops producing visible hair, no current treatment reliably brings it back.
Does masturbation or wearing hats cause male pattern baldness?
No. Neither has any established link to male pattern baldness. The condition is driven by genetics and DHT sensitivity in certain scalp follicles.
