Male and female pattern hair loss: what works according to the evidence

Noticing your hair thinning at the crown, a widening parting or a receding hairline is unsettling, and understandably so. Androgenetic alopecia, better known as male or female pattern hair loss, is the most common reason for it in both men and women ^[1]. It follows a recognisable pattern, progresses slowly and, while it cannot be cured, it can be slowed down. This guide sets out what the scientific evidence actually says, without promises or shortcuts.

What pattern hair loss is and why it happens

It is gradual hair loss that follows a pattern. It often starts in the teens or twenties and becomes more common with age. According to the European guideline, it affects up to 80% of men of European descent and 42% of women ^[1].

The cause is a mix of genetics and hormones. Some scalp follicles overreact to androgens, particularly dihydrotestosterone ^[2]. With each growth cycle, those follicles shrink, a process called miniaturisation: they produce hair that is finer, shorter and shorter-lived. Eventually some stop producing visible hair at all ^[10].

A hormonal component does not mean your hormones are out of balance. In most men and women with pattern hair loss, hormone blood tests are normal: what changes is how sensitive the follicle is.

In men

The typical pattern starts at the temples, the crown or both. Over the years the two areas can merge. The Hamilton-Norwood scale grades this progression and is useful for comparing photos over time.

In women

Female pattern hair loss usually spares the front hairline. The usual picture is diffuse thinning over the top of the head, with a parting that gradually widens. It is the most common form of hair loss in women and can weigh heavily on quality of life ^[3]. The Ludwig scale describes its stages.

There is one important nuance for women. If hair loss comes with irregular periods, acne or excess body hair, it is worth checking for raised androgens from the ovaries or adrenal glands ^[3].

How it is diagnosed

In most cases a good medical history and a look at the scalp are enough ^[3]. Trichoscopy, a magnifying lens for the scalp, helps to see miniaturisation and to rule out other causes. A scalp biopsy can confirm the diagnosis but is rarely needed ^[3].

Above all, the doctor looks for anything that does not fit pattern hair loss:

• Sudden shedding by the handful, which points more towards telogen effluvium.
• Round, sharply defined bald patches, typical of alopecia areata.
• Red, scaly or scarred-looking skin, which means a scarring alopecia has to be ruled out.

A blood test is not always needed. It is requested when your history suggests it: to check iron or thyroid levels or, in women with other signs, hormones. Two problems often coexist, for example pattern hair loss and low iron, and both need treating.

Which treatments have evidence behind them

Not everything sold for hair loss works equally well. Here is where the evidence stands, from strongest to weakest.

Doctor-led medical treatment

This is the foundation of treatment and the option with the strongest evidence. There are two broad families: treatments that stimulate hair growth, applied to the scalp or taken by mouth, and anti-androgen treatments, which reduce the effect of androgens on the follicle. A meta-analysis of randomised trials found that the treatments studied outperformed placebo in men and, for scalp-applied treatment, in women too ^[2].

For women, the Cochrane review pooled 47 trials with 5,290 participants. Scalp-applied treatment was effective, with moderate to low-quality evidence; oral options have fewer and weaker trials ^[4]. Even so, oral anti-androgen treatment is used in selected women in clinical practice, with good results in mild to moderate cases ^[3].

Several of these medicines are prescription-only in Spain. Which option suits you, and at what dose, depends on your sex, age, health, pregnancy plans and any medication you already take. That is a decision for your doctor, not a catalogue.

Low-level laser

These are light devices, shaped as a helmet, cap or comb, used at home. A meta-analysis of 38 studies found greater hair density than placebo in pattern hair loss, although results varied widely between studies ^[8]. It can be a sensible add-on, not a replacement for medical treatment.

Platelet-rich plasma (PRP)

PRP means injecting a platelet concentrate, made from your own blood, into the scalp. In a network meta-analysis PRP ranked among the most effective options for men, but the quality of that evidence was judged low ^[5]. Another analysis showed that its effect depends heavily on the protocol: more sessions, closer together, gave better results on average ^[6]. You can read more about PRP for hair loss.

Scalp mesotherapy

Mesotherapy involves micro-injections of various substances into the scalp. A systematic review found improvement in some studies, but with no standardised protocols and with reported side effects ^[7]. For now it is a complementary option with limited evidence.

Hair transplantation

A transplant moves follicular units from the back of the scalp, which does not respond to androgens, to thinning areas. Not every type of hair loss can be operated on, and choosing the right candidate matters most for the result ^[9]. A transplant does not stop the untransplanted hair from thinning.