No matter the cause, female hair loss can be devastating to deal with. And, you might be unaware of how common it is. In fact, 49% of women experience hair loss at some point in their life [1]. And, age often doesn't matter, with women in their 20s commonly experiencing hair loss.

Whether you’re experiencing thinning hair, balding spots or a receding hairline, it can be difficult to get to grips with understanding what’s happening and what you might be able to do to treat it. There are various causes of hair loss in women, ranging from medical treatment to hereditary causes, and even trauma from hairstyling. 

Here’s everything you need to know about the causes of female hair loss and female pattern baldness.

How does hair grow?

Most of us don’t give it a huge amount of thought but hair growth is actually incredibly complex. Each hair follicle is known as a “mini organ” made up of the blood vessels, nerves, a hair papilla, hair bulb, root, follicle and shaft [2]. 

If you’re unfamiliar, hair goes through four growth stages: anagen, catagen, telogen, and exogen. 

Anagen phase

First is the anagen phase, which is the period of active growth. During this time, blood flow in the scalp provides oxygen to cells in the hair bulb that divide and produce something called keratinocytes, which are essentially hardened cells.

These hardened cells eventually form a protein called keratin, creating a strong strand of hair. This phase can last anywhere between 3-7 years. 

Catagen phase

Next up is the catagen phase, which is known as the period of transition and lasts about 2-4 weeks. During this time, the production of keratinocytes stops and the hair follicle shrinks, separates from the papilla and the blood supply is cut off. 

Telogen phase

The telogen phase is next, which is the resting phase, and where the hair loss name telogen effluvium comes from (more on that later!) During this time, the stand is dormant for a number of months. 

Exogen phase

The final phase is called the exogen phase, which is sometimes referenced as part of the telogen phase. It is the period of hair shedding. 

Once the hair is shed, the process starts all over again and active growth begins. In healthy hair, new hair growth cells are constantly being formed. 

How much hair loss is normal?

Of course, losing hair is a part of life and is entirely normal, so when do you know when you’re experiencing hair loss? Each stage of growth for each stand is different, which means you won’t suddenly find your entire head of hair in the growth or resting stage at once. 

On average, you can lose 70 to 100 hairs each day [3]. If someone isn’t experiencing hair loss, this shedding shouldn’t be noticeable. But if you’re experiencing excessive shedding or your hair remains in the resting phase longer than the growth phase, you may be noticing more hair loss.

What is androgenetic alopecia?

Androgenetic alopecia, also known as female pattern hair loss or male pattern hair loss, is a genetically determined type of hair loss and is the most common cause of hair loss. For some experts, using the term female pattern hair loss is preferred over androgenetic alopecia due to the uncertainty of the role of androgens in hair loss.

In women, these hair loss changes can start as early as 12 years old [4]. It happens due to a hormone called dihydrotestosterone (DHT), which is derived from testosterone and shortens the anagen (growth) phase. It also makes the hair follicles shrink, which causes thinning; this is known as miniaturisation [5]. 

In both men and women, hair loss presents differently and at varying rates. In men, this presents with a receding hairline and balding crown and in women, it presents more as overall thinning. Women rarely go bald due to this condition, but men can. 

Interestingly, if we’re talking about body hair (or androgenic hair) (for example, beards), DHT is actually needed to grow this hair. That’s why some people might have little to no hair on their heads but an impressive beard. 

Although this hair loss is genetic, there are certain lifestyle factors that can contribute to hair loss. 

What causes hair loss in women?

There are lots of causes of hair loss in women. The most common is genetics, which often means you can feel out of control with your hair loss. But there are also lots of other common causes, and lots you can do to help slow down or treat hair loss.

Stress

Besides genetics, the second biggest factor of hair loss in women is due to stress. This can be prolonged work-related or emotional stress or acute periods of stress brought on by traumatic accidents or a stressful event.

This type of hair loss is called telogen effluvium and occurs when the hair is in the telogen phase for longer than normal, meaning the hair follicles remain dormant and shed. Since it’s a non-scarring type of hair loss, it is temporary and for a lot of people, it generally only lasts for around 6 months [6].

Childbirth

Hair loss is also common after childbirth, this is often referred to as telogen gravidarum or simply postpartum hair loss.

During pregnancy, women have a high level of something called placental oestrogen in their body which actually prolongs the period of the anagen phase (the growth phase) of hair, which is often why a lot of women find their hair is longer and fuller than ever.

However, after birth — typically around 2-5 months after birth — the withdrawal of these hormones leads to all of these hairs entering the shedding phase at once [6].

Dieting

It might not seem like it but diet, specifically, nutritional deficiencies, can have a huge impact on your hair. Follicles need plenty of nutrients to keep the blood flow healthy and in a consistent growth cycle. In a lot of common types of hair loss, there are a few deficiencies present. 

The first is iron — which is the most common nutritional deficiency — and it impacts the cell division right at the beginning of the anagen phase and therefore impacts growth [7]. 

Another common deficiency is zinc (found in red meat, tofu, lentils, beans and dairy products) as your body can’t generate this on its own so supplements and food are necessary.

The next is niacin (vitamin B3), with a deficiency in such called pellagra, which is rare nowadays and often found in those with malabsorption disorders and alcoholism [7].  

Lastly (though this list is by no means exhaustive) is protein, which can be a common cause of hair loss through diet if someone is experiencing rapid weight loss. In fact, it's common for people to experience hair loss (specifically telogen effluvium) changes through restrictive dieting.

This is because a lot of rapid dieting and weight loss involves cutting out entire food groups, leaving out much-needed vitamins and minerals. It’s always best to work with your doctor before cutting out food groups or starting a diet. 

Thyroid problems

Thyroid problems, whether it’s hyperthyroidism or hypothyroidism, can impact a whole host of issues in the body, including hair loss and thinning hair. 

When the thyroid hormone T3 and T4 are disrupted, the development of the hair in the anagen phase doesn’t work as it should, which in turn, can cause thinning and breakage. 

Because of this, it can actually cause other areas of the body, such as the eyebrows, to experience thinning too [8].

PCOS

Since polycystic ovary syndrome is a hormonal condition, it’s not entirely surprising that it can impact your hair. This hormonal imbalance can lead to androgenic alopecia, often due to an increase in dihydrotestosterone (DHT).

As we touched on above, these effects caused by DHT are what make it possible that the hair on your head is thinning or shedding and yet you’re experiencing more body hair than before. 

The good news is that hair loss due to PCOS can often be remedied with the right hormone-balancing medication. Hormone regulation is an important part of treatment so it’s always best to discuss it with your healthcare provider.

Tight hairstyles

Tight hair styling practices can affect hair loss over time, specifically contributing to a type of permanent hair loss called traction alopecia. You might notice bald spots or patchy hair loss.

This type of hair loss occurs due to excessive pulling of the hair strands over time, which can break strands and damage the follicle. Common hairstyles that cause this include: cornrows, tight buns and ponytails, tightly braided hair, weaves or hair extensions [9]. 

To avoid this, it’s recommended to switch up your hairstyle regularly and try to wear loose styles as well where you can.

Iron deficiency

Iron is the most common nutrient deficiency and unfortunately, it can impact hair growth. Now, it’s not yet clear how significant the deficiency has to be to experience hair loss and it’s not yet known exactly how hair growth is impacted [7]. Because of this iron and female pattern hair loss is debated but lots of studies suggest a link. 

It’s thought that a deficiency in this macronutrient impacts the very early stages of the anagen phase in hair growth by limiting the oxygen supply to the cells. A study from 2013 found an interesting link between iron deficiency and telogen effluvium in pre-menopausal women [10].

Can female hair loss grow back?

When it comes to hair loss growing back, the answer isn’t so cut and dry. In short: it depends on what type of hair loss it is as to whether there is a hair loss treatment available.

For acute types of hair loss such as telogen effluvium, the shedding is only temporary so it will grow back. Make sure you’ve got a well-balanced diet and are avoiding tight hairstyles and things like rough brushing and handling all help.  

You can also do things like include a gentle head massage into your showing routine to stimulate hair growth.

If you’re experiencing hereditary hair loss like female pattern hair loss or scarring alopecia, then it may not grow back, but there are things you can do to reduce the speed of the hair loss. We recommend speaking to your doctor or dermatologist for next steps when it comes to treatment.