How Birth Control Pills Work
At the beginning of each menstrual cycle, estrogen levels begin to rise, and the lining of the uterus thickens in preparation of a fertilized egg (this period is called ovulation). After ovulation, progesterone, another reproductive hormone, rises preparing for a fertilized egg. Conception occurs when a fertilized egg implants in the uterine wall. If conception does not occur, both estrogen and progesterone levels drop, signaling the thickened uterine lining to shed and ushering in menstruation.
Oral contraceptive agents, also known as “birth control pills” (i.e., OCAs, BCPs) are a synthetic mixture of the hormones progesterone and estrogen. They prevent ovulation by maintaining constant levels of these hormones. As a result, the ovary does not release an egg and the estrogen level does not rise.
What Are Risks Involved With Taking Oral Contraceptives?
Oral contraceptives (OCA) can be associated with increased risks of several serious side effects. Women taking them are advised not to smoke due to an increased risk of blood clots, stroke and heart attack. Importantly, they do not protect against HIV infection or other sexually transmitted diseases.
Birth Control Pills Causing Hair Loss
BCP’s can cause hair loss in women through two different mechanisms, through drug induced shedding and by facilitating female pattern genetic hair loss. These are two very distinct processes.
Almost any drug can potentially cause hair loss but oral contraceptives are particularly implicated in a process called telogen effluvium, or hair shedding. Essentially, what happens is that the drug causes hair in the growing phase (anagen) to be shifted to the resting phase (telogen). After the telogen phase (normally lasting about 2-3 months), hairs are spontaneously shed before they enter a new growth cycle (of 3 – 7 years). Normally only about 10-15% of hairs are in telogen at any one time, but this can increase to as much as 50% in telogen effluvium. As a result, large amounts of hair can be shed as they pass through this short telogen cycle. Interestingly, telogen effluvium can occur with starting birth control pills, switching birth control pills, or even discontinuing the BCPs that a patient has been on for a long period of time. Fortunately, this process can be reversible once the implicating agent is stopped or the scalp has time to adjust to the new medication.
If a woman has a genetic predisposition for hair loss, then oral contraceptive medications containing progesterone can potentially increase that loss by adding a source of exogenous (outside) androgens. The birth control pills that are higher in progesterone compared to estrogen will more likely contribute to this process. In contrast to hair shedding, the thinning seen in genetic hair loss is characterized by a progressive decrease in hair shaft diameter rather than frank hair loss.
Birth Control Pills As Treatment For Female Pattern Hair Loss
Just as progesterone dominant BCPs can facilitate female pattern hair loss, oral contraceptives higher in estrogen can stimulate hair growth by prolonging the anagen phase of the growth cycle. A problem is that estrogen dominant birth control pills have a greater incidence of certain side effects. Your gynecologist should advise you on which BPCs should be used in your particular situation.
The newer oral contraceptives such as Yasmin, Yaz, Desogen, Mircette, Ortho-Cyclen, Ortho Tri-Cyclen and Ortho Tri-Cyclen Lo have lower androgenetic effects and are useful in patients concerned about hair loss. In particular, Yaz and Yasmin contain the progestin drospirenone, which has anti-androgen properties, and can therefore be particularly helpful in women experiencing female pattern hair loss.
Low-androgen Birth Control Pills
Here is a list, made available by the American Hair Loss Association, of low-androgen birth control pills (listed from lowest androgen index to highest):
- Ortho Tri-Cyclen
- Nor-Q D
- Ortho Norvum 7/7/7
- Ortho Novum 10-11
- Norinyl and Ortho 1/35
- Demulen 1/35
- Loestrin 1/20
- Loestrin 1.5/30
Visit our section on the Causes, Classification, and Diagnosis of Hair Loss in Women