Birth Control Pills, Hormones and Hair Loss: Important Considerations

Birth Control Pills affect Androgens

Oral contraceptives have many effects on the hair.  For some  women, oral contraceptives can cause hair shedding when started or stopped by triggering a telogen effluvium. Fortunately for most, this shedding is temporary.  Oral contraceptives can also benefit the hair in many women with androgenetic alopecia by reducing the levels of androgens (male type hormones) in the blood.

Where do androgens come from? 

There are three important sources of androgens in women.  About 50 % of testosterone in the blood comes from the conversion of hormones such as androstenedione and dehydroepiandrosterone (DHEA) and its sulphate dehydroepiandrosterone sulphate (DHEA-S). About 25 % of testosterone comes form the adrenal gland and 25 % from the ovary. 

About 65 % of testosterone that circulates in the blood stream gets bound and inactivated by sex-hormone-binding globulin (SHBG). Most of the remaining 30–35% is bound by albumin. Only 0.5–3% represents freely circulating T ("free T"). Despite the low amount, free T is important as it is active and able to cause a range of clinical phenomena such as hair loss acne and increased hair growth on the face (hirsutism).

Effects of Oral Contraceptives Pills on Androgens

Oral contraceptives (birth control pills), particular the combined oral contraceptives (COCs) are known the levels of androgens in the blood including testosterone, androstenedione and DHEAS. For example, blood levels of testosterone decrease by as much as 50 %. This occurs from the ability of oral contraceptive pills to a) reduce androgen synthesis in the ovary b) reduce androgen synthesis in the adrenal gland and c) increase sex hormone binding globulin in the liver. 

Because of their effects on androgens, birth control pills are options for women with certain types of hair loss, including androgenetic alopecia associated with normal hormone levels, and androgenetic alopecia associated with polycystic ovarian syndrome (PCOS).  Birth control pills are not appropriate for everyone with these hair loss conditions and anyone considering these medications should carefully review risks and benefits with a physician.