Understanding Hormonal Hair Loss (Part One)

Hair can be a precious and defining part of personal identity - whether we choose to show it or not, so it is normal to feel some anxiety if we begin to notice excessive hair loss or clumps in the shower. 

The internet is overloaded with scary (and sometimes, not always accurate) information. That’s why we’ve created this guide, so we can summarise the most important scientific evidence and explain hormonal hair loss in women, what hormones cause hair loss and how.

The truth is, hair loss is affected by a wide range of factors. Some of these are more internal, like your genetics and your nutrition. Others are more external factors like the quality of the water that you use to shower, the level of stress you are experiencing and even the hairstyles you are creating!

But amongst all of these, there is one very powerful player that holds a crucial role in regulating our hair growth, and that’s our hormones. They are signalling messengers that travel all around your body to influence everything ranging from your mood, metabolism and, yes, even the growth cycle of your hair!

So let’s take a closer look at what we mean by the hair cycle.

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The Hair Growth Cycle

The hair cycle is basically what your hair shaft goes through from beginning to the end of every day. It’s an ongoing, silent and painless process that happens on the top of your head (without you even realising).

It’s made up of four main phases: anagen (growth), catagen (transition) and telogen (rest) and exogen (shedding).

• Anagen/growth phase: During the anagen/growth phase, your hair is happily growing at about a rate of 1cm/month, bursting out of its root follicle and gaining length. This phase can last between 2-3 years for some individuals, but can also go as long as 5-7 years for others. During that phase, your hair will reach the absolute maximum length it can ever achieve. If you were to take a closer look, you’d notice that about 85-90% of your hair will be in that phase.

• Categen phase: Following that, your hair is now ready to enter its transition, or catagen phase. This stage is significantly shorter between 2-3 weeks on average. During this time, your hair will stop growing and will start detaching from the underlying blood supply that is giving it all the fuel to lengthen. At any given time, only about 3-5% of your total hair is actually in this transition phase. It’s the time when the hair gets ready to say goodbye to its cozy spot on your head.

• Telegen phase: Next comes the resting phase, or scientifically called the telogen phase. Your hair is now fully formed, is now over this whole growing phase and has decided to settle and live a calm life. Around 10-15% of your hair will be in that phase during the growth cycle. During that time, the hair is still in the follicle, it’s just not interested in doing particularly much.

• Exogen phase: Lastly, we get to the final step of the cycle, the exogen phase. This step is also known as the shedding phase and sometimes considered an extension of the previous phase. The hair shaft now proceeds into detaching itself from the hair follicle on your scalp and falls out. This is unlike hair loss, which happens when your hair doesn’t grow back, shedding is expected and natural, and about 50-100 hairs per day are lost that way.
  

Hormones and Hair Loss: Where and How do They Step in?

Now that we have walked through the wonderful journey that is the life story of our hair, ranging from its enthusiastic growth to its peaceful farewell, you might be wondering what hormones have to do in all of this.

Imagine Hormones as Messengers

Hormones are incredibly important and are the key messengers of a variety of functions in your body. They travel through your bloodstream, sending specific signals to different organs. So, they cancarry out their designated role and create harmony in your body. For example, one of the main contributors of your hair cycle is oestrogen. Its main impact is seen during the growth phase of your hair as it will mainly prolong the duration of that phase, which means that your hair will have more time spent growing and in length-gaining mode.

Interesting fact: during pregnancy, hair can feel thicker and healthier and this is mainly to do with the fact that oestrogen levels are very high to support the healthy development of the fetus.

Androgens Have a Vital Part to Play

Androgens, which is an umbrella term used for another group of hormones, also play a very important role in hair growth regulation. You may recognise names like testosterone, or its more potent byproduct, dihydrotestosterone (DHT). They are both naturally found in the body, in both men and women: while testosterone is made in the testes in men, it’s also made in much smaller concentrations in ovaries and adrenal glands in women. 

DHT is Essential for Normal Hair Growth

Meanwhile, DHT is produced in areas like the skin and hair follicles. It’s essential for normal hair growth in areas like the face and body, but can unfortunately have the opposite effect on the scalp - especially if you are sensitive to it. Some people have a genetic predisposition that makes their hair follicles more susceptible to DHT. In this context, "sensitive" means that follicles react more strongly to normal circulating levels of the hormone, leading to a shorter hair growth cycle and shrinking of the follicle, which can all eventually lead to hair thinning. So in reality, it’s not actually about how much circulating testosterone or DHT is present, but how your scalp follicles interpret and respond to them.

Don’t Forget About Progesterone 

Another important key player is progesterone, the balancer. It’s also produced in both men and women, but in significantly higher amounts in women and even sometimes up to 200 times more. Unlike oestrogen, progesterone does not target the hair cells directly and its exact role in hair growth is still not fully understood. It’s believed to help maintain a balanced hormonal environment around the hair follicles. One of the ways it can achieve that is by inhibiting an enzyme called 5-alpha reductase, which is a naturally occurring molecule that speeds up certain physiological processes, including converting testosterone into the potent DHT. Since DHT is very closely linked to hair shrinkage in certain individuals, progesterone could be helping by suppressing its production.

When Hormones Shift: Situations That Affect the Cycle

We now know that hormones are the behind-the-scenes stars of the cycle, but what happens when they stop performing as well as they should, and start missing some key cues or behaving oddly? Well…things can get a little bit more unpredictable.

Firstly, let’s preface this section by reassuring you - shedding your hair is totally normal. It is in fact, expected, but up to a certain degree. As mentioned, we lose between 50-100 hairs a day, as part of the exogen phase. These hairs are older, tired, and are stepping away to make space for new and fresh ones. 

However, if you start noticing that your hair is falling in clumps, your middle part or temple areas start widening or your bun just feels thinner than usual, this could mean that there is something happening beneath the surface, literally. More often than not, hormones and shifts in their physiology are a key piece of the puzzle. They will not only have an effect on the timing and duration, but also the overall health and efficiency of the cycle, leading to higher proportions of shedding.

Let’s take a look at some common situations and life moments that can impact how your hair behaves:

Post-partum/After Birth Period

During your pregnancy, your oestrogen levels reach an all time high. It plays a huge role in extending the duration of the hair growth phase but after giving birth, these levels drop quickly and steadily. That sudden shift in oestrogen concentration puts the hair in a bit of an alarm, and shifts a huge proportion of your hair in the transition phase, also known as the telogen phase. About 2-3 months later, this big chunk of your hair transitions into the exit phases of shedding, also known as telogen effluvium. This shift can also be caused by nutritional change, physical stress or even medication, and may be very noticeable. The good news is, this is all temporary and due to an unusual pattern in your hormones. Everything tends to go back to normal within a few months.

Perimenopause & Menopause 

As the body approaches menopause aka cessation of menstruation, oestrogens levels start to decline gradually. However, your androgens, like testosterone and DHT, do not necessarily go down at the same rate. This can create an unbalanced scale with less oestrogens and more androgens, and for some women, it can lead to thinning and hair loss along the crown or the middle part of their hair. This can be in a similar distribution that is seen in male pattern hair loss.

Polycystic Ovarian Syndrome (PCOS)

PCOS is commonly seen in women with higher levels of androgens which lead to a shorter hair growth anagen phase. The result? Thinner hair, slower regrowth and sometimes patchy thinning is more noticeable around the temples and crown of your head. The confusing part is that many people with PCOS notice unwanted hair growth in other parts of their body, like the chin, jaw or chest which we may be able to attribute to higher androgens.

Thyroid Hormones 

The thyroid gland is one of your body’s metabolic control centres, playing a major role in regulating your energy levels, temperature, mood and your hair cycle. Such a multitasker, but with high responsibility comes high stakes. When it’s underactive (hypothyroidism), your metabolism slows down, which can lead to diffuse hair thinning, dryness and brittleness. When it’s overactive (hyperthyroidism), everything speeds up, which can throw off your hair cycle. Your body may go into stress, pushing more hairs into the telogen phase and causing premature shedding. Don’t panic though, if caught early and treated, your hair cycle usually returns to normal within a few weeks to months. If you’ve been noticing hair loss, feeling unusually tired, or experiencing weight changes, it might be worth checking your thyroid function with your doctor!

Can My Genetics Affect My Hormones s Well?

Hair growth is a complex process and there are lots of players in the game. We can’t talk about your hormones without giving a special spot to talk about the role of your genetics in all of this!

Your DNA, or genetic material, plays a big role in how your hair behaves, but it’s really important to note that it’s very susceptible to your hormones and will respond to the message it’s being sent by them.

One of the clear examples of this is something called androgenetic alopecia, also known as DHT sensitivity. It is quite a mouthful, but what it means is that it’s a genetic predisposition, or tendency, to experience hair thinning and loss as a response to your naturally occurring hormone levels. The more casual and widely known name is male-pattern hair loss, it does not only happen in men and affects women too. 

People with this genetic background happen to be more sensitive to a hormone called DHT (dihydrotestosterone), which is essentially a byproduct of testosterone naturally found in your body. It circulates in your bloodstream, in both men and women alike, but just not at the same levels.

People with a predisposition to androgenetic alopecia will have hair follicles that are innately tuned to overreact to DHT, and that leads to their gradual shrinkage of hair follicles. This will eventually lead to thinner, shorter and weaker hair strands over time as the time they spend in the growth phase will also decrease - meaning less hair growth occurs.

To find out more about the treatments available to those with hormonal hair loss, check out part two of our guide. 

Hormonal Hair Loss in Women: a Spectrum

If you’ve been reading through this and thinking, “oh dear, I feel like I can relate to so many of these things and all at the same time!”, you are not alone, and in fact, many people feel this way. The truth is, hormones tend to impact several things at the same time, oftentimes leading to multiple conditions all being present simultaneously.

You may have been told that what you’re experiencing is androgenetic alopecia, or telogen effluvium due to stress, or a symptom of your PCOS. The reality? It’s all a blend of several overlapping factors and effects.

For example, someone might have a genetic predisposition to DHT, while also having just given birth recently, as well as going through personal life stressors. This will usually result in a sudden wave of hair shedding that might not always respond to just one single treatment or lifestyle modification.

Our body reacts to all sorts of physical and emotional changes, and hair is another important part of that picture. Hormonal hair loss in women is very complex and very real. 

You are not imagining it, and you are not alone!

Understanding how your hair cycle works - and the powerful role hormones, genetics, and life changes play in it - is the first step toward making sense of what you’re experiencing. While the causes of hair loss can feel overwhelming, there are effective ways to manage it. In Part 2, we’ll look at the treatment options and lifestyle approaches that can help you take back control.

For answers to other questions you might have about hair care, check out our blog page.