Common Causes of Hair Loss in Women

common causes of hair loss in women

Hair loss affects around 30-50% of adult women. It can take a huge toll on mental health and self confidence, so we often see women reaching for quick solutions or creams. For the best and most long lasting results we need to determine WHY your hair is falling out at a more rapid pace than usual. There are so many underlying factors that can contribute to hair loss or thinning. So, it is important to get a proper workup, including lab testing in order to receive targeted treatments. 

Understanding the hair cycle

Before we talk about common causes of hair loss, we need to first understand the different phases that our hair goes through.

Anagen phase: this is the active growth phase. Around 80% of our hair follicles are in this phase, and they can remain here for around 3-7 years. The hair follicle receives nutrients from a blood supply, and our hair continues to grow.

Catagen phase: this is the transition phase that lasts around 1-2 weeks. The hair detaches from the blood supply and stops growing.

Telogen phase: this phase begins with a resting period of 3 months. Here, the hair rests in the root while new hair grows beneath it. Around 10-15% of our hair is in this phase. However, if we enter this phase prematurely we may experience hair loss or thinning as we tend to lose more hairs than we are growing.

Each hair follicle goes through these phases independently, at different times so we are not losing all of our hair at once. On average, we have around 100,000 strands of hair on our head and we lose around 100 strands per day. Clinical hair loss occurs when we lose more than this, notice clumps of hair falling out or thinning areas on our scalp.

What are common causes of hair loss in women?

Hair loss can be a result of many different factors. Below are the most common reasons I see hair loss in women:

Hormone imbalances

Androgenic Alopecia

This is the most common cause of hair loss in women, and the incidence increases as we age. It is due to elevated androgens, particularly DHT (or dihydrotestosterone). DHT is a very potent form of testosterone that binds to receptors on the hair follicle and causes the hair to fall out. Other androgens that may be a factor include DHEA-S or androstenedione, which are secreted from the adrenal glands.

Additional symptoms of high androgens include irregular menstrual cycles, acne, oily skin or hirsutism (coarse hair growth on areas such as the face, between the breasts, abdomen and inner thighs). This is a common form of hair loss in PCOS. In fact, around 35% of women with PCOS and 40% of women with hirsutism have elevated DHT1. This hair loss tends to be localized to the temporal area or the crown of the head. This is because there are 1.5x more androgen receptors in these areas of the scalp1.

Aromatase and 5-alpha-reductase

Additionally, there is an enzyme known as aromatase that converts testosterone to estrogen. This has anti-androgenic effects that protect the hair from falling out. The presence of this enzyme in the frontal region is only half as high as other areas of the scalp, such as the occipital region. Therefore, there may be more local testosterone in the frontal region of the scalp, which can lead to hair loss. In men, aromatase in this region is 6x lower than in women, which may be a reason why we often see hair loss in the frontal region in male-pattern baldness2.

Testosterone converts to DHT through an enzyme called 5-alpha-reductase. Treatment options for androgenic alopecia often target or inhibit this enzyme to reduce the conversion and therefore lower levels of DHT. Common treatments include finasteride or topical minoxidil (Rogaine), however there are more natural alternatives that also inhibit 5-alpha-reductase. These include zinc, green tea, saw palmetto and nettles.

Additional hormones that can contribute to hair loss are SHBG (sex-hormone binding globulin) and prolactin. SHBG binds excess hormones in the blood. Therefore, when levels of SHBG are low we may see higher levels of testosterone or DHT. When prolactin is high, it has effects on the adrenal glands and can increase levels of DHEA1. This type of hair loss is often more diffuse.


Hair loss after giving birth is very common. We often see this around 3-4 months after delivery. This is because during pregnancy, the placenta secretes large amounts of estrogen and progesterone which support hair growth and the health of our skin and nails. After delivery and the removal of the placenta, the hormones rapidly decline and it can take several months for hormones to regulate again.

Hair loss often occurs 3 months postpartum because the hair stays in the telegen, or resting phase, for 3 months. So, even though hormone levels drop before this, we often don’t notice a change until a few months later.

Once the hormones start to become balanced again, hair loss will stop or slow down. This often takes around 6-12 months.

Thyroid imbalance

Another common concern where we may see hair loss is in thyroid disease, particularly in hypothyroidism or Hashimoto’s thyroiditis (autoimmune hypothyroidism).

Our thyroid hormones are crucial for virtually every function in our body. There are receptors for thyroid hormone in our hair follicles and an under-active thyroid is a common cause of hair thinning or hair loss. Other common symptoms of a sluggish thyroid include weight gain, brain fog, fatigue, heavy periods, feeling cold, experiencing dry skin or brittle nails, constipation, low mood, anxiety, difficulties conceiving or low libido.

Hair loss associated with thyroid dysfunction often presents as more diffuse hair loss, rather than in the temporal or crown region with androgenic alopecia. You may also experience thinning of the outer part of the eyebrows.

Nutrient deficiencies or malabsorption

Since the hair is a non-essential tissue, it often receives nutrients last because our more vital organs will require and utilize these nutrients first. Iron and protein intake are likely the most important factors when we’re talking about hair loss, but other micronutrients and minerals such as zinc, selenium and biotin should also be considered.

It is important to get comprehensive testing, including a complete blood count and ferritin (the storage form of iron) in order to rule out iron deficiency as a cause of hair loss. On blood work, ferritin should be over 60ng/ml in order to prevent hair from falling out. Other symptoms of iron deficiency include fatigue, heavy periods, heart palpitations, looking pale and feeling short of breath.

Vitamin D deficiency is correlated to hair loss, especially relating to alopecia areata, which is an autoimmune condition that attacks hair follicles3. Testing for vitamin D is done through bloodwork, and we are often looking for levels to be above 100nmol/L.

A balanced diet is the best way to prevent nutrient deficiencies, but proper supplementation may be necessary to correct a deficiency.


This one is often overlooked, but stress is a huge factor when dealing with hair loss and this is something that I see often in women.

Chronic stress inhibits hair growth and contributes to local inflammation that may lead to hair thinning or hair loss4. When cortisol is elevated, it can reduce the growth of hair and increase the destruction of important building blocks such as hyaluronan and proteoglycan by around 40%4. Stress causes the hair cycle to prematurely enter the “resting phase”, resulting in sudden shedding with little hair growth. Stress and elevated cortisol can also lead to elevated androgens, which contribute to androgenic alopecia. 

You can test your cortisol via bloodwork or through saliva or urine. This must be collected first thing in the morning in order to get accurate results, as cortisol should be highest in the morning and decline as the day progresses.

Lab testing to consider

  • free and total testosterone
  • DHT (dihydrotestosterone)
  • DHEA-S
  • androstenedione
  • estradiol
  • progesterone
  • full thyroid panel (TSH, free T3, free T4, reverse T3, anti-TPO, anti-TG)
  • Complete blood count (CBC)
  • ferritin
  • vitamin D
  • cortisol
  • SHBG
  • prolactin

Naturopathic treatment options for hair loss

Treatments will depend on lab results and the underlying driving factors in your specific case. Your treatment may include a combination of prescription or compounded topical solutions, oral supplementation or adjunct therapies like PRP, steroid injections or light therapy to the scalp.

Talk to your naturopathic doctor if hair loss is a concern for you. It is often a symptom of a further imbalance.


  1. Urysiak-Czubatka, I., Kmieć, M. L., & Broniarczyk-Dyła, G. (2014). Assessment of the usefulness of dihydrotestosterone in the diagnostics of patients with androgenetic alopecia. Advances in Dermatology and Allergology, 4, 207–215.
  2. Ramos, P. M., & Miot, H. A. (2015). Female Pattern Hair Loss: a clinical and pathophysiological review. Anais Brasileiros De Dermatologia, 90(4), 529–543.
  3. Lin, X., Meng, X., & Song, Z. (2019). Vitamin D and alopecia areata: possible roles in pathogenesis and potential implications for therapy. Am J Transl Res, 11(9), 5285–5300.
  4. Thom, E. (2016). Stress and the Hair Growth Cycle: Cortisol-Induced Hair Growth Disruption. J Drugs Dermatol, 15(8), 1001–1004.

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