Hair & hormones: Which hormones cause hair loss

We’ll address common hormonal hair loss questions such as “which hormone causes hair thinning?” and “how do medical conditions like PCOS and thyroid disorders affect hair?” We’ll also discuss the most common ways in which hormonal changes that happen throughout life can affect hair, including changes during the menstrual cycle, hormonal birth control, pregnancy, postpartum, and perimenopause.

How hormones affect hair growth

First things first, what exactly are hormones, and why are they messing with your beauty regimen? Hormones are naturally occurring chemicals in the body that regulate many of your major internal systems and functions. You can think of them as messengers that travel through your bloodstream with instructions telling your organs and tissues what to do, how to do it, and when. They play a huge role in maintaining a healthy body, but they can also cause some less-than-desirable effects when they’re out of balance [1].

Hair growth basics

Before we dive into the causes of hair thinning, let’s take a step back and look at the basics of hair growth. While hormone fluctuations and imbalances can lead to many different conditions in the body, hair growth and hair thinning patterns are one of the most noticeable. To understand which hormone causes hair thinning, we’ll need to understand the science behind the hair growth cycle first.

This cycle is influenced by everything from stress to metabolic function to nutrition and hormones. It flows as follows:

1. Anagen phase: This is when individual hairs actively grow and produce strong, thick strands. Typically, this phase lasts 2–7 years, and the presence of the hormone estrogen helps to prolong this phase (more on this later). At any given time, up to 90% of your hair is in the anagen phase.
2. Catagen phase: This short transitional phase lasts about two to three weeks. During this time, the hair follicle starts to shrink and stops producing new hair, preparing the follicle for rest.
3. Telogen phase: This phase lasts for about two to three months, and it’s when the follicle is inactive and resting. This means that it’s holding the hair in place until it naturally sheds. 
4. Exogen phase: During this phase, newly developing hair within the follicle grows upward, pushing the old hair out and resulting in both shedding and the beginning of a new anagen phase.

[2]

Which hormones cause changes to the hair?

Throughout our lives, hormones can play many different roles in our hair health. To answer the question of which hormone causes hair thinning specifically, let’s dive a little deeper into how certain hormones can affect the normal cyclical hair growth pattern:

• Cortisol: Chronic high stress means elevated levels of cortisol, the body’s primary stress hormone. When raised for long periods, cortisol can damage the cells that build hair and increase the number of follicles entering the resting/shedding phase. [2].
• Estrogen: the sex hormone estrogen can delay the transition intp the catagen phase, which means that if there is more estrogen present in the body (as there is during pregnancy), your hair will likely grow longer and thicker. It also balances androgen levels in the body, further delaying the catagen and telogen phases [2].
• Progesterone: Progesterone also plays more of a protective role in maintaining the anagen phase by lowering the amount of DHT produced. A drop in progesterone, which may happen during an event like childbirth or during perimenopause, can cause hair to shift into the shedding phase [3].
• Androgens: Increased levels of androgen hormones like testosterone and the more potent dihydrotestosterone (DHT) can shrink hair follicles over time, which may lead to weaker hair strands and an overall pattern of thinning [3]. Even though androgens are usually classified as “male” sex hormones (because men typically have higher levels of them), everyone has androgens present in their body (just like males have low levels of estrogen and progesterone, too) [4].
• Thyroid hormones: Hormones that regulate thyroid function (called T3 and T4) also influence hair growth phases. They can even influence hair structure and pigmentation as well [5].

Of course, your first port of call if you’re concerned about your hormonal health should be your doctor’s office. Together, you and your healthcare provider can discuss your unique experience and the possibility of testing your hormone levels for specific treatments tailored to you.

How hair changes throughout the menstrual cycle

Now that we’ve established that hair follicles respond to fluctuating hormones, you may be wondering if the fluctuations that happen during the monthly menstrual cycle can affect your hair. Many people seem to experience “bad hair days” and other beauty issues like breakouts around the time of their period, and although scientific research has yet to confirm large-scale evidence of this phenomenon, there are a few potential explanations as to why this happens [6].

It’s normal to notice changes to your hair in the luteal phase (after ovulation). Many women report that their hair can feel greasy in the lead-up to their periods. One short-term study confirms this, finding that women with excess oil production on the scalp generally had the highest levels of oil in the week before menstruation (during the luteal phase). But this same study did not find any differences in women with lower scalp oil levels, and only tracked participants for three consecutive cycles [7].

Aside from that finding, there is more evidence to suggest that shifting hormones throughout the menstrual cycle can have a direct effect on the way we feel about our self-image. Studies have shown that women tend to have lower levels of body satisfaction and perceived self-attractiveness during the luteal phase specifically [8]. In other words, we tend to be much harder on ourselves during the latter half of our cycle. 

So while hormones do play a role in our self-image, and that can be confusing and frustrating to navigate, the fact remains that there is limited evidence to suggest that hair quality changes throughout the menstrual cycle. This is partly because the hair-growth cycle itself unfolds over years, not weeks or months, making it unlikely for short-term hormonal fluctuations to noticeably alter growth or thickness. As ever, if you have questions or concerns, it’s worth talking to your healthcare professional for further investigation.

Can hormonal birth control affect hair growth?

Many types of birth control contain synthetic hormones. These work by altering the levels of our natural sex hormones to inhibit ovulation, thicken cervical mucus, or prevent the implantation of a fertilized egg cell. It’s only natural to wonder then if these synthetic hormones may have an effect on your wider hormonal health, and hair health for that matter. 

Methods like the combined birth control pill contain a combination of synthetic estrogen and progesterone (progestins), whereas some methods (like the IUD or the implant) contain progestins only — read our guide to learn more about the different types of hormonal birth control and how they work.

There is a theory that synthetic progesterone can have androgenic properties, and some women, who already have a genetic predisposition to hair loss, may find they experience a higher level of shedding while taking this type of contraception [9]. This shedding is thought to be caused by shrinking hair follicles, leading to a type of thinning known as androgenetic alopecia [10]. 

It’s important to note that there is limited evidence in the link between hormonal birth control and hair loss, and this is not a commonly cited side effect of birth control, such as the pill.

Will my hair change if I stop taking hormonal birth control?

On the other hand, you may actually experience more shedding than usual if you stop taking certain types of hormonal birth control. This is due to the sudden drop in levels of synthetic estrogen and progesterone. The good news is that this shift is usually temporary [11].

If you still want to prevent pregnancy, it’s important to find a solution that works for you. Thinking about switching birth control methods? Natural Cycles is a hormone-free alternative to traditional birth control,  with zero side effects. Talk to your doctor to learn more.

Hair changes in pregnancy

If you’ve recently become pregnant, you may be wondering if hair changes are on the horizon for you during this new stage of life. The short answer is yes — many women report thicker, fuller hair during pregnancy, and it’s just one of the effects that contributes to the legendary “pregnancy glow.” Pregnancy hormones (especially estroge) extend the growth phase of hair follicles, leading to less shedding and a fuller appearance. [12].

Alternatively, you may be feeling more stress during pregnancy, leading to increased cortisol. As we outlined above, cortisol and other stress hormones can contribute to hair thinning and shedding. Either way, whether you’re experiencing thicker hair or hair loss during pregnancy, your hair growth cycle should rebalance in a few months after giving birth once your hormones have returned to their previous levels [12]. 

Talk to your healthcare provider and/or care team if you’re concerned about the effects of pregnancy hormones on your hair quality, and remember that you can always seamlessly switch from NC° Birth Control to NC° Plan Pregnancy and NC° Follow Pregnancy for extra support along your fertility journey.

Hormonal hair thinning postpartum

Natural Cycles also supports you after childbirth with NC° Postpartum. After giving birth, it’s common to notice more hair falling out. In fact, one study found that over 90% of women experience postpartum hair shedding [13]. While it can be an uncomfortable and distressing postpartum symptom, it’s a natural part of the recovery experience, and shouldn’t lead to any permanent hair loss or bald spots [12].

As for the timeline, shedding may peak around four months postpartum, but it should resolve within about a year after childbirth once your hormones return to pre-pregnancy levels [14]. 

Hair thinning in perimenopause

You may also experience several kinds of hair changes as part of the perimenopause transition (the life stage leading up to menopause, which is the last menstrual period in a woman’s life). While you may not experience full hormonal hair loss, some of the most common hair symptoms you’ll see in perimenopause includes:

• Increased shedding overall
• Changes in texture, becoming more dry and brittle
• More sparsity around the crown and hairline
• More scalp visibility overall [3]

While this is the general experience of many perimenopausal women, it's important to remember that your experience may be different, as everyone’s perimenopause journey is unique. It’s also sometimes difficult to discern which of these hair effects stem directly from hormonal shifts during perimenopause or are simply a natural part of aging.

Regardless, these symptoms can be tough to deal with mentally and emotionally. If you’re experiencing perimenopausal symptoms such as hair thinning, fatigue, weight gain, night sweats, or joint pain that are interfering with your everyday life or affecting your well-being, talk to your healthcare professional for advice and treatment options. 

Perimenopause is an impactful life stage and looks different for everyone. Changes to our bodies, with new symptoms emerging is not unusual. But that doesn't mean there aren’t steps you can take to support your journey – NC° Perimenopause is built to help you decode symptoms and support you throughout the perimenopausal transition. Take our perimenopause quiz and find out whether your symptoms might be linked to this life phase and how Natural Cycles can best support you.

Hair changes and hormonal conditions

Aside from the hormonal shifts that happen throughout different life stages, you may also experience hormonal conditions like PCOS, endometriosis, and certain thyroid conditions at any point in life. These conditions can affect your hair growth patterns and overall hair quality as well.

• PCOS: This condition is characterized by increased androgen (testosterone and DHT) levels, which may be linked to excessive hair growth on the face or body (known as “hirsutism”) [15].
• Endometriosis: Although endometriosis itself doesn’t usually affect hair, some treatments can. Certain treatments for endometriosis like GnRH agonists cause estrogen levels to drop [16]. Whilst not very common, these medications may push more hairs into the shedding phase and result in hair loss [17]. 
• Thyroid conditions: Underactive hypothyroidism and overactive (hyperthyroidism) thyroids can affect hair growth. As many as 50% of people with hyperthyroidism experience hair thinning, the number is lower (but still significant) for those with hypothyroidism, with around 30% experiencing some kind of hair thinning [18].

Steps to promote healthy hair and manage hair loss

Overall, hormonal hair thinning can happen for a variety of reasons over the course of our lives, and although there isn’t much we can do to change our genetics or certain life circumstances, there are a few things we can do to manage hormonal hair loss and thinning patterns:

Consult a healthcare provider

We want to underscore that the best way to address any kind of hair thinning is by seeing a specialist — like a dermatologist, an endocrinologist, or your primary healthcare provider — to assess the root cause, and treat that cause specifically.

Maintain healthy hair routines

How we treat our hair can affect its health, and the first step in promoting healthy hair often requires maintaining a healthy scalp. Keeping your scalp clean with regular, gentle cleansing and scalp massages can support the healthy functioning of those follicles, and create a better ecosystem for hair growth overall, so building scalp care into your haircare routine could be a valuable tool to promote overall hair health [19].

Additionally, avoiding excessive heat styling and chemical treatments can reduce damage and help your hair maintain its natural texture and strength. This may mean opting for air drying instead of a straightener or curling iron, and pulling back on hot oil treatments and at-home coloring for a bit [19].

Support hormonal balance with lifestyle and dietary changes

But not all lifestyle changes are as obvious. As we established earlier, hormonal hair thinning is often due to an excess or lack of certain hormones. To keep your hormones in balance as best you can, certain practices like consuming a nutritious diet, getting quality sleep each night, exercising regularly, minimizing alcohol and tobacco use, and managing stress where possible can help [2, 19]. (We know — much of this is much easier said than done.)

Try certain supplements (but check with your doctor)

Making sure your diet contains essential nutrients such as iron, Omega-3s, vitamin D, and Zinc can make a difference in your hormone health as well. These are usually available as supplements that you’ll find over-the-counter, but remember to consult with your healthcare provider before starting any new vitamin regimen (we can’t recommend that enough), as getting too much of certain nutrients can actually contribute to hair loss [2,19].

To take supplementation one step further, did you know that there is early evidence to suggest that some naturally occurring ingredients may block or help to treat certain underlying causes of hormonal hair loss? They’re called “DHT blockers,” and they include:

• Saw palmetto* [20]
• Pumpkin seed oil [21]

*Keep in mind that Saw Palmetto is not recommended for use by pregnant or breastfeeding women [22].

Get hormonal hair thinning support with Natural Cycles°

Thanks for reading up on the relationship between hair and hormones. Our bodies, hormones, genetics, lifestyles, and circumstances are exceptionally unique — and all of these can affect our hair. That’s why it’s helpful to have tools on hand like Natural Cycles that meet you where you are, whether that’s getting pregnant, postpartum, or through perimenopause and beyond.

At Natural Cycles, we’re dedicated to destigmatizing these conversations and closing the knowledge gap on women’s health to allow you to live confidently. Our FDA-cleared app offers individual hormonal support at any stage of life. Why not find out if Natural Cycles could work for you today?