Progesterone is a naturally occurring steroid hormone primarily involved in regulating the menstrual cycle and preparing the uterus for a potential pregnancy. It is produced mainly by the ovaries following ovulation, with levels rising significantly to maintain the uterine lining. When considering a link between this hormone and facial hair, it is important to distinguish between the body’s own progesterone and the synthetic versions used in medications. The relationship is not straightforward, requiring a detailed look at how different hormonal compounds interact with the hair follicle.
Progesterone’s Relationship with Androgen Activity
Natural progesterone, the hormone made by the body, has little to no androgenic effect; in fact, it can sometimes act as a weak anti-androgen. It may compete with potent male hormones, like testosterone, for binding sites on the androgen receptor, potentially lessening their impact. This natural hormone does not typically cause physical symptoms of male hormone excess, such as increased facial hair growth.
The complexity arises with synthetic versions of the hormone, known as progestins, which are used widely in birth control and hormone therapy. Progestins have diverse chemical structures, and some are derived from testosterone, retaining varying degrees of androgenic activity. Progestins like levonorgestrel or norethindrone can exert a male-hormone-like effect, leading to side effects like acne or hirsutism. Newer synthetic progestins, such as drospirenone, are structurally related to the anti-androgen spironolactone and may possess anti-androgenic effects.
Hirsutism: The Mechanism of Terminal Hair Growth
Hirsutism is the appearance of thick, dark facial hair in a pattern typically seen in males. This hair growth results from androgen activity on the hair follicles, regardless of the trigger. Hair follicles exist in two main types: vellus hair, which is fine, short, and lightly pigmented, and terminal hair, which is coarse, long, and pigmented.
Androgens, specifically testosterone and its more potent derivative, dihydrotestosterone (DHT), transform vellus hair into terminal hair. DHT is produced when the enzyme 5-alpha-reductase converts testosterone directly within the hair follicle. The severity of hirsutism depends on the amount of circulating androgens and the hair follicle’s sensitivity to them. The mechanism of hair growth is always the stimulation of the follicle by an androgenic compound.
Situations That Cause Hormonal Hair Changes
Hormonal hair changes often become noticeable during specific life stages or when a person begins medical treatments. Hormone Replacement Therapy (HRT) is a common scenario, where the introduction of certain synthetic progestins can accelerate hair growth. The progestin component of HRT, which is necessary to protect the uterine lining, can have an androgenic effect, promoting the growth of terminal hair. Balancing the estrogen and progestin type is often necessary to mitigate this side effect.
Another common trigger is the hormonal shift that occurs during and after menopause. As estrogen and natural progesterone levels decline, the body’s androgen levels remain relatively higher in proportion to the female hormones. This relative androgen excess can lead to the new or increased appearance of facial hair, as the follicles become more sensitive to unopposed androgens.
Underlying medical conditions are a third, and often primary, driver of hirsutism. Polycystic Ovary Syndrome (PCOS) is the most frequent cause of androgen-related hair growth in women of reproductive age. PCOS causes the ovaries to produce excessive androgens, leading to hirsutism, often alongside symptoms like acne and irregular periods. Less common conditions, such as non-classic congenital adrenal hyperplasia (CAH), also lead to excess androgen production and unwanted hair growth.
Managing Unwanted Facial Hair
Managing unwanted facial hair involves addressing the underlying hormonal cause and using various removal methods. For those whose hirsutism is driven by conditions like PCOS, systemic treatments are often prescribed to lower androgen levels or block their effects. A common prescription is the anti-androgen medication spironolactone, which blocks androgen receptors and reduces testosterone production. Results typically take six months or more to become noticeable.
Topical treatments offer a localized approach to managing facial hair growth. Eflornithine cream is the only FDA-approved topical treatment for facial hirsutism in women. It works by inhibiting the enzyme ornithine decarboxylase in the hair follicle, which slows the rate of hair growth and makes the hair finer. The cream must be applied twice daily, and consistent use is necessary to maintain results.
Many people choose cosmetic removal techniques for immediate relief. Laser hair removal uses concentrated light to damage the hair follicle, while electrolysis involves inserting a fine probe to destroy the follicle with an electrical current. These methods are often combined with hormonal treatments for comprehensive and long-lasting results. Consulting a dermatologist or endocrinologist is the first step to accurately diagnose the cause of hair growth and determine the most appropriate treatment plan.