Common causes of hair loss: a complete guide

The most common cause of hair loss in men is male pattern baldness (MPB), known as male androgenetic alopecia. It affects 30-50% Trusted source National Center for Biotechnology Information (NCBI) Government Source Biomedical Research and Literature Go to source of men by the age of 50 and causes 95% of cases of male hair loss.

Male pattern baldness is linked to the hormone dihydrotestosterone (DHT). Cells in the scalp convert testosterone, the male hormone, into DHT. DHT causes the hair follicles to shrink and the hair to grow back thinner each time. This eventually causes the hair to fall out.

This type of hair loss usually runs in families and occurs naturally as you age. Experts Trusted source PubMed Government Source Database of Biomedical Research Go to source have identified up to 63 genes that could affect whether you will experience hair loss.

While it cannot be prevented, treatment options like finasteride can slow or even reverse early signs of hair loss. You can also get surgical hair transplants.

Women also experience pattern hair loss, known as female androgenetic alopecia or female pattern hair loss (FPHL). Unlike male pattern baldness, women don’t lose their hair. The hair thins on the scalp, causing your parting to get wider.

Like in men, FPHL is typically hereditary. You’re more likely to experience it if you have a family history of it. As you age, the number of hair follicles shrinks and reduces which causes the thinning hair appearance.

In some women, it is due to an imbalance of hormones. It is common in women with polycystic ovary syndrome (PCOS) as they have higher levels of male hormones. It is also common during menopause as oestrogen levels drop.

Your doctor may recommend treatment for FPHL. Some women take Minoxidl which is a solution applied directly to the scalp. If the cause is hormonal, your doctor may recommend an anti-androgen treatment like spironolactone.

Certain hair styling practices can cause hair loss. This is because the constant pulling damages the hair follicles, which prevents the hair from going back. This type of hair loss is known as traction alopecia.

This is common in certain hairstyles, such as:

• tight buns, ponytails or up-dos
• cornrows
• dreadlocks
• hair extensions or weaves
• tightly braided hair
• hair rollers

Wearing these hairstyles too often can cause the hairline to recede and irritate the scalp.

Overuse of hair straighteners, curling irons and hair dryers can also lead to hair loss. It is linked to one type of alopecia called Central Centrifugal Cicatricial Alopecia (Scarring Alopecia).

As soon as you see any noticeable signs of hair loss, you should change your hairstyle. This is because often the hair does not grow back. So, acting early can prevent further hair loss.

If you’re worried about this type of hair loss, you should consult your GP or a dermatologist.

There are a group of conditions that cause hair loss. This is where the body mistakenly attacks the hair follicles and causes hair loss.

Alopecia areata

The most well-known type of autoimmune hair loss is alopecia areata. It is relatively common, affecting up to 1 in 1000 Trusted source National Institute for Health and Care Excellence (NICE) Government Source Go to source people in the UK.

Experts are still unsure what triggers the immune system to react, but it could be a combination of factors (e.g. an infection or environmental factors).

It can range in severity:

• Alopecia areata - causes round or oval bald patches on the scalp or other parts of the body where hair grows.
• Alopecia totalis - causes a total loss of scalp hair.
• Alopecia universalis - causes total hair loss across the scalp and face, including eyebrows and eyelashes as well as across the body.

It affects most people in childhood. It is also linked to a family history of alopecia or another autoimmune condition.

There is, unfortunately, no cure for alopecia areata, but in some cases, hair loss is not permanent.

Lichen planopilaris

Lichen planopilaris is a type of hair loss that irritates the scalp. The immune system attacks the hair follicles and replaces them with scarring. This blocks the hair follicle and causes permanent hair loss.

The exact cause is unknown but it is believed a type of white blood cell is involved. Evidence suggests that some genes may make people more susceptible to developing the condition.

Unfortunately, hair loss is permanent. But, some treatments may help to keep the remaining hair. The condition may also become inactive, meaning you stop losing hair.

Frontal fibrosing alopecia

Frontal fibrosing alopecia (FFA) is known as a localised version of lichen planopilaris. This is because it only affects the front part of the scalp, making the hairline recede.

Like lichen planopilaris, the immune system attacks hair follicles and replaces them with scarring. Similarly, an exact cause or trigger is unknown. But, it is particularly common in postmenopausal women.

Certain types of cancer treatment can cause hair loss. This type is known medically as Anagen effluvium.

Cancer treatments like chemotherapy are designed to be toxic to any rapidly growing cell in the body, which includes any cancer cells but also the cells in the hair follicle.

Cancer treatment affects everyone differently. But, hair loss is gradual and usually starts within 2 - 3 weeks of starting treatment. It does not cause complete hair loss, but many people choose to shave their heads for comfort.

Your hair usually grows back after you finish cancer treatment. Different treatments may cause your hair to grow back more slowly, but it usually starts to grow back within 3 - 6 months.

You may also be offered a cooling cap during treatment to prevent hair loss. It is a closely fitted cap cooled by chilled liquid. This slows blood flow which stops the effect of cancer treatment on the hair follicles.

Telogen effluvium is a type of hair loss that occurs when some kind of stress to the body disrupts the hair growth cycle. It causes a large number of hairs in the growing cycle to go into the resting phase. This causes these hairs to shed.

Many factors can cause this type of hair loss, such as:

• emotional trauma
• rapid weight loss
• iron deficiency
• severe infection
• major surgery
• hormonal changes (e.g. after childbirth or due to a condition like thyroid problems)
• certain medications (e.g. birth control)
• conditions affecting the scalp (e.g. ringworm or seborrheic dermatitis)

Usually, this type of hair loss is short-term and is resolved when you treat the underlying cause. However, it may take some time for the hair to regrow.

A more uncommon condition that causes hair loss is known as trichotillomania.

This is a psychological condition where someone has strong urges to pull out their hair. This can be hair from your scalp, face or body. Some people are not conscious while they do it but others may do it intentionally.

The condition commonly develops during childhood between the ages of 10 and 13. It may have a genetic element, as it can run in families. It can also be linked to other mental health disorders like obsessive-compulsive disorder (OCD) or anxiety.

Constant pulling can damage the scalp and permanently affect your hair growth. So, your doctor may recommend therapy to help you cope with the condition.