GP and medical author Dr Deborah McManners reveals the most common causes

What causes hair loss?

Age
In our twenties and thirties we typically have 615 hair follicles per square centimetre. The number falls to 485 by the time we hit 50 and to 435 at 80. Each hair also becomes thinner, therefore reducing hair volume.

A poor diet
Hair thrives on a plentiful supply of protein, vitamins and minerals. In fact, a lack of protein is often at the root of hair loss and because hair is considered ‘non-essential’ by the body, if you’re lacking in nutrients it will often be your hair that suffers first. Eating badly affects new growth which slows or can halt altogether, leading to excess shedding, hair breakage and weak connection of the hair strand at the root.

A reaction with the male hormone testosterone
Both men and women have the male hormone testosterone circulating in the blood. Some sensitive individuals, often genetically determined, can be more sensitive to what is called an Androgenetic Alopecia with the male hormone triggering hair loss.

Cancer
Hair loss is a common side-effect of chemotherapy. Lost hair usually starts to grow back within six months of the end of treatment.

Diabetes
Diabetes is a disorder that can have a very gradual onset which reduces the overall state of health which may affect hair growth.

Medicines
Medicines which in some cases may have hair loss as a side effect include cholesterol lowering agents, ulcer healing agents, anti-diabetic drugs, blood pressure medication and birth control pills.

Menopause
During the menopause hair can feel thinner as hormone levels fall. For women with a family tendency to hair loss, it can become apparent at this time.

Polycystic Ovary Syndrome (PCOS)
Women with Polycystic Ovary Syndrome can experience loss hair due to a hormone imbalance and increased sensitivity to the male hormones we all have.

Pregnancy and childbirth
When a woman is expecting a baby, pregnancy hormones delay the shedding phase. After delivery, many hairs enter the resting and shedding stage causing what seems to be a huge amount of hair to fall out at once.

Smoking
Scientists in Taiwan discovered men who smoked 20 or more cigarettes per day had a greater chance of developing baldness. Cigarette smoking has been shown to cause poor circulation, which can affect the amount of blood flow available to the hair follicles of the scalp.

Stress
Stress affects many people and is one of the most common reasons for hair loss. Its effects are often not instantaneous – typically occurring between four and 16 weeks after the stress point.

Styling
Over-styling, heat treatments, hair extensions and frequent use of strong chemicals on hair can break the hair shaft and cause thinning and slow growth.

Thyroid conditions
An overactive or under active thyroid gland can often lead to hair loss due to changes in hormone levels.