Why men lose their hair

For the large majority of men, hair loss comes down to one cause: male pattern hair loss, also called androgenetic alopecia. It is genetic, hormonally driven, and completely normal, which does not make it any less frustrating to watch happen.

The mechanism is well understood. In genetically susceptible men, hair follicles are sensitive to a hormone called DHT, which over time causes them to miniaturise, producing progressively finer, shorter hairs until they stop producing visible hair at all. It usually begins at the temples and crown.

  • Male pattern hair loss. By far the most common cause, following the familiar pattern of a receding hairline and thinning crown.
  • Stress and lifestyle. Significant stress or illness can accelerate shedding, sometimes months after the trigger.
  • Medical and nutritional factors. Thyroid conditions, certain medications and deficiencies can contribute, which is why a proper history matters.
Up to 50% by age 50 of Caucasian men experience some degree of hair loss, and possibly as many as 80% by age 70. Other population groups, including Japanese and Chinese men, are far less affected.

Source: DermNet, Male pattern hair loss. General population research, not clinic outcomes.

The single most useful thing to know

It is easier to keep the hair you have than to recover hair that is gone. Because male pattern hair loss is progressive, the window where treatment can do the most is while follicles are still active, before an area has been smooth and bald for years.

It also starts earlier than most men expect. The Cleveland Clinic reports that around 25% of men see the first signs of hair loss before the age of 21, which is why noticing something in your twenties is not unusual and not something to dismiss.

This is not a scare tactic, it is just the biology. If you are noticing thinning now and wondering whether to wait, a scan gives you a clear, honest picture so you can decide with real information rather than worry.

When to see your GP instead

Male pattern hair loss is the most common explanation, but it is not the only one, and some causes need a doctor rather than a clinic. Speak to your GP first if any of the following apply.

Worth a doctor's opinion
  • Hair is coming out in distinct round patches rather than thinning gradually.
  • You are losing hair from other parts of the body, or eyebrows and eyelashes.
  • The shedding is sudden or very heavy, rather than slow over years.
  • There is itching, pain, scaling or scarring on the scalp.
  • You feel unwell generally, or have noticed other changes such as fatigue or weight change.

Your GP can arrange blood tests where relevant, including iron studies and thyroid function, and rule out causes that are treated medically rather than in a clinic. We would rather send you there first than sell you something that was never going to help. You can read more in our guides on blood tests for hair loss and the different types of hair loss.