Our hormones play a significant role within our body – from everyday processes and functions to fertility and emotional reactions. Issues with our hair can also have hormonal components to it, from oily scalps and hair thinning to a sudden boost in hair fullness – it’s not uncommon for hormones to often be the cause!
The relationship with our hormones starts when we are born and continues throughout our entire lives. From hair-loss-causing androgens such as DHT to hair-boosting oestrogen, hormones play one of the most vital roles in our hair and scalp health.
Our hair’s structure and growth cycle (click here to read all about the hair’s growth cycle) are directly impacted by our hormones. Hormones are the body’s chemical messengers that govern and coordinate the body’s processes, functions, and health. Fluctuations in sex, stress, and thyroid hormones can all have various effects on the hair and scalp, both good and bad!
Hormones and our hair…
Oestrogen
Oestrogen is the powerhouse female sex hormone produced by the ovaries that works to power the menstrual cycle and secondary sexual characteristics. See below for Oestrogen’s effects on the hair and scalp:
- Oestrogen aids hair growth by extending the anagen phase (growth) of the hair’s cycle.
- It moderates the production and metabolism of androgen hormones, which are the culprits of hair thinning.
- It can accelerate hair growth and contribute to softer, thicker, healthier hair.
- During pregnancy, when oestrogen levels are high, it prolongs the growth phase of the hair cycle leading to less shedding and thicker hair.
- After pregnancy, a sudden drop in oestrogen can lead to postpartum hair loss as the hair transitions into the catagen stage of the hair’s cycle. Postpartum hair loss is common and temporary.
- Oestrogen promotes water retention and plumpness to the skin. During menopause or postpartum – when oestrogen levels drop - the scalp tends to become drier and more sensitive - leading to flaking, itching, and irritation, all of which can exacerbate hair loss or hair thinning.
Progesterone
Working nicely alongside oestrogen is progesterone, a female sex hormone that is responsible for the menstrual cycle and pregnancy. See progesterone’s effects on the hair below:
- Progesterone is a natural hair loss inhibitor. It decreases the conversion of testosterone to DHT by blocking the activity of the enzyme called 5-alpha reductase. Therefore, lowered progesterone during menopause, postpartum or among those with polycystic ovarian syndrome (PCOS), allows hair-loss-triggering DHT to be produced rapidly and freely, causing hair thinning and shedding.
- In women with PCOS, a lack of regular ovulation leads to low progesterone levels and elevated androgen levels. As progesterone is a natural androgen blocker and protects the hair follicle from the effects of DHT, women with PCOS cannot effectively inhibit the effects of the heightened androgens and can experience hormonal hair thinning.
DHT (dihydrotestosterone)
Dihydrotestosterone or DHT is a male sex hormone (A.K.A androgen) that is a more potent form of testosterone. DHT is produced from testosterone by an enzyme called 5-alpha reductase, which converts a certain percentage of the body’s testosterone into DHT to contribute toward certain functions, including maintaining body hair and muscle mass. See the effects of DHT on the hair below:
- DHT can shorten the anagen (growth) phase of the hair cycle, while lengthening the time between the telogen (resting) and new anagen phase.
- DHT is primarily responsible for follicular miniaturisation, in which the hair follicle shrinks, producing a shorter and thinner hair shaft. During follicular miniaturisation, hair follicles that were once producing healthy hairs start to generate thinner hairs with more fragile shafts.
- During menopause, both oestrogen and progesterone decrease, but DHT increases in comparison. As a result, many women will experience increased shedding, delayed new hair growth and finer, thinner hair.
- DHT triggers sebaceous glands on the scalp causing them to overproduce sebum, leading to an oilier and greasier scalp. This can cause follicle blockages, inflammation, and build-up, leading to more hair shedding and thinning.
Cortisol
Cortisol is the body’s primary stress hormone. Stress is our natural defence system against threat and danger, but too much of it can have a detrimental effect on our hair:
- Increased levels of cortisol produced by long periods of stress inhibit the hair’s growth by keeping the hair cycle in extended periods of the telogen phase (resting).
- Cortisol prevents the dermal papilla (a cluster of specialised cells that reside at the base of the hair follicle) from secreting a key molecule that activates hair follicle stem cells.
- Inhibiting cortisol production – and therefore stress – leads to more rapid hair regrowth.
- The primary form of cortisol-induced hair loss is called Telogen Effluvium and refers to a sudden onset of hair loss that is usually triggered by stress, trauma or serious illness. It results in an excessive amount of hair loss in which up to 70% of anagen hairs can abruptly shift into the telogen phase (versus the normal 15% that elicits shedding before a new anagen phase). Telogen effluvium is temporary and reversible once the stress or illness has been brought under control.
Thyroid Hormones
- Our thyroid hormones control our metabolism. The two primary hormones released by the thyroid gland are thyroxine (T4) and triiodothyronine (T3). See the effect these hormones can have on our hair below:
- When thyroxine (T4) and triiodothyronine (T3) are disrupted, the hair follicle can also become disrupted. This is often seen with hypothyroidism.
- Hypothyroidism is associated with telogen effluvium, along with the appearance of dry, brittle, and dull hair strands. Hyperthyroidism can lead to thinning of the hair shaft diameter as well as brittle, greasy hair. People with overactive thyroids can also experience a loss of tensile strength in their hair, as well as premature greying.