The Hormone-Hair Connection: What Science Says About Hair Growth

Ever wondered why you're shedding more at some times of the month? Why birth control influences hair growth? Or that pregnancy gave you the best hair of your life - until 3 months postpartum when it all fell out? Your hormones are pulling the strings.

How hair grows

First, let's look at the basics. Hair growth occurs in three different stages

Anagen - this is the growth phase. 

This is when your hair is actively growing and can last between 2-6 years. Don’t worry, most of your hair is in this phase at any given time! 

Catagen - this is the transition phase, where your hair is more stable. 

Hair growth stops in this phase, and the hair is no longer attached to the blood supply (but still attached to your head!).

Telogen - rest phase. RIP to your strand of hair. 

No hair growth is occurring, but the hair stays attached to your scalp until shedding occurs. Shedding normally occurs 3-6 months after this phase is completed. 

Estrogen: Your Hair’s Best Friend

There are two main hormones that control women’s lives - estrogen and progesterone. Estrogen is the one mainly involved in hair health. How? 

Estrogen binds to receptors on hair follicles and can influence hair growth through gene expression alterations, immune system interaction and estrogen production through enzymatic expression. 

1. Activates growth genes

When estrogen binds to the estrogen receptor, it activates a downstream growth signaling pathway. This can activate genes that are required for hair growth and support the hair follicle cycle. 

1. Creates an anti-inflammatory environment

Estrogen can also interact with immune cells which can promote anti-inflammatory environments around the hair follicles, promoting a healthy environment for the hair follicle to grow!

1. Boosts conversion of testosterone to estrogen

Estrogen bound to its receptor can increase aromatase activity, which is an enzyme that turns androgens like testosterone into estrogen. More estrogen = more hair growth! 

Androgens and hair follicles 

Androgens, specifically testosterone, work against estrogen. They can inhibit the growth signaling cascade that estrogen activates, leading to reduced hair growth. On top of this, testosterone can increase inflammatory cytokines, creating a toxic environment for hair follicles and hair growth and maintenance. 

What happens when hormones go awry and impact hair?

In a normal menstrual cycle, there are natural fluctuations of estrogen which can affect how the hair grows and shines in a cyclical manner. Estrogen peaks during ovulation and drops in the late luteal phase. This means that during the luteal phase there could be more hair shedding compared to the follicular phase. If you’ve ever taken a combined contraceptive pill and stopped, you could have experienced hair loss. Though evidence is limited, it could be due to the added synthetic hormones suddenly being taken away, leading to imbalance, and causing hair follicles to enter the telogen phase prematurely. 

In pregnancy, there are high estrogen levels, which helps promote hair follicles into the growth phase and can make hair look more full. However, after pregnancy, as estrogen levels drop dramatically, these hairs switch to the telogen phase, and immense shedding can occur shortly after. 

Additionally, women who have PCOS often have higher testosterone levels. Higher testosterone levels promote the growth of hair in male sexual pattern areas such as the chin and chest. However, on your scalp, increased testosterone can lead to female pattern hair loss, which occurs in 22% of those with PCOS. 

As estrogen levels drop and androgen levels rise, the hairs in menopausal women change. For one, hair loss can occur as estrogen can no longer keep hair follicles in the anagen phase, and they start to switch to telogen. Secondly, estrogen is an important factor of metabolism, which takes a hit as we enter menopause. Since hair follicles require energy to produce more hair, this can result in age related hair loss or a stunt in hair growth. Additionally, estrogen is a vasodilator in premenopausal women. As we age and estrogen levels drop, blood vessels provide less blood to hair follicles, which is dangerous for their health and growth. In menopause, as estrogen decreases, there becomes more available testosterone in the blood stream, allowing it to reach hair follicles and inhibit hair growth on the scalp. 

Practical strategies to help

1. Nutrition 

Nutrition is a powerful tool to help nourish your hair. By introducing anti-inflammatory foods and supplements, like Omega 3 fatty acids can help create a healthy environment for hair growth. Additionally, vitamin D3 and zinc can help regulate hair cycles to promote hair growth. Iron supplementation can prevent hair loss and promote growth, as iron deficiency is linked to reduction or complete cessation of hair growth. 

1. Managing stress 

Studies have shown that stress induced hair loss is real - and it is bidirectional. The more you stress, the more hair you shed, and the more hair you shed the more stressed you can become. 

Breaking this cycle requires stress management. Do what works for you - journaling, meditation, being in nature, breathwork and being with friends or family have all been proven to reduce stress. 

1. Looking after your hair 

Keeping consistent with your haircare helps to maintain shine, softness, and long-lasting hair health. Using a hair mask like the Miracle Mask from Josh Wood Colour helps to deeply condition, moisturise whilst restoring softness and strength. Pair this with gentle washing, heat protection, and regular trims to keep hair nourished, resilient, and looking beautifully healthy every day.

References:

Gupta AK, Economopoulos V, Mann A, Wang T, Mirmirani P. Menopause and hair loss in women: Exploring the hormonal transition. Maturitas [Internet]. 2025 May 2;198:108378. Available from: https://www.sciencedirect.com/science/article/pii/S0378512225001860?via%3Dihub

Ach Taieb, Amri Feryel. Deciphering the Role of Androgen in the Dermatologic Manifestations of Polycystic Ovary Syndrome Patients: A State-of-the-Art Review. Diagnostics. 2024 Nov 16;14(22):2578–8.

Rajput RJ. Influence of Nutrition, Food Supplements and Lifestyle in Hair Disorders. Indian Dermatol Online J. 2022 Oct 21;13(6):721-724. doi: 10.4103/idoj.idoj_175_22. PMID: 36386748; PMCID: PMC9650738. 

O'Sullivan JDB, Peters EMJ, Amer Y, Atuluru P, Chéret J, Rosenberg AM, Picard M, Paus R. The impact of perceived stress on the hair follicle: Towards solving a psychoneuroendocrine and neuroimmunological puzzle. Front Neuroendocrinol. 2022 Jul;66:101008. doi: 10.1016/j.yfrne.2022.101008. Epub 2022 Jun 2. PMID: 35660551.