Male-pattern baldness (androgenetic alopecia) runs in families. It is thought to be caused by hair-producing follicles becoming hyper-sensitive to dihydrotestosterone (DHT), an androgen which is created by the male hormone testosterone via enzymes. DHT causes hair follicles to shrink and eventually stop producing hair.
Female pattern baldness may also be genetic and mostly affects post-menopausal women (falling oestrogen levels may play a role) and an under-active thyroid (hypothyroidism) can also cause thinning hair.
Alopecia areata causes patches of baldness in men and women. It is caused by a problem with your immune system and is more common in people with an over-active thyroid or diabetes. In most cases, hair grows back within several months.
Telogen effluvium is caused by hormonal or physical stress, which temporarily puts hairs into their dormant (telogen) phase. Sufferers lose handfuls of hair at a time. It is common after childbirth, with between a third to a half of women affected. Other causes include crash dieting, anorexia, sudden weight loss, iron deficiency, major surgery, serious illness and sometimes medication.
Hair loss can also follow a course of chemotherapy treatment for cancer.
Male-pattern baldness usually begins with a receding hairline, then hair on the crown thins, but hair on the back and sides of the head remains. In women, the pattern is less obvious, mainly affecting the top of the scalp, gradually thinning out all over, with a widening parting.
Alopecia areata causes coin-sized bald patches on your scalp, though it can develop into Alopecia universalis, which results in total hair loss on head and body. Telogen effluvium causes widespread thinning of hair, but not bald patches.
Your GP can examine your hair and diagnose your type of hair loss. Your doctor will ask about the timing and pattern of your hair loss, any medical problems, family history of hair loss, possible hormonal factors such as menopause or pregnancy and any changes in your diet. Your GP may want to do a blood test to rule out a thyroid disorder or anaemia.
Who gets hair loss?
Half of men over 50 are affected by male-pattern baldness, although early signs can begin in teenage years and white men are four times more affected than Afro-Caribbean men.
Around one in three white women over 70 have female-pattern baldness and it’s more common after the menopause. Some 15 per 10,000 people have alopecia areata in the UK, it’s most common between ages 15 and 29 and around one in five affected have a family history of the condition. Telogen effluvium is most common in women after having a baby or following a crash diet.
For male-pattern baldness there are two medicines that can be effective. Finasteride is available on private prescription from your GP and is a daily tablet. It works by preventing testosterone being converted into DHT (which shrinks hair follicles), allowing hair follicles to regain their normal size. It takes three to six months to work.
Minoxidil can be bought from pharmacies, either as a two per cent or five per cent lotion. Rubbed into your scalp daily, it can help slow hair loss and may trigger regrowth. It takes at least four months to work.
For female-pattern baldness treatment only two per cent minoxidil is licensed. This can be bought from pharmacies and is rubbed into your scalp twice daily and studies have shown good results with minoxidil two per cent in women.
Other treatments include hair transplants, where a small area of the scalp with plenty of hair growing is removed, split up and grafted onto areas with no hair growing. It's not available on the NHS and is very expensive.
Acrylic wigs are available on the NHS, but wigs made from real hair are not available unless you have an allergy to acrylic and can cost up to £2,000.
Vitamin D deficiency may be linked with women’s hair loss. A study found only 38 per cent of women with female pattern baldness had a normal vitamin D level.