The Connection Between Hormones and Your Hair
Hair growth is a cyclical process, and hormones play a significant role in regulating it [1.2.1]. Hormonal contraceptives, including birth control pills, function by adjusting the body's levels of synthetic estrogen and progestin to prevent pregnancy [1.2.2]. While effective, these hormonal shifts can disrupt the natural hair growth cycle, leading to hair loss in individuals who are sensitive to these changes [1.8.6].
This disruption can manifest in two primary ways:
- Telogen Effluvium This is a temporary form of hair shedding that occurs when a significant stressor—like a hormonal shift from starting, stopping, or switching birth control—pushes more hairs than usual into the resting (telogen) phase of the hair cycle [1.3.1, 1.3.6]. This results in diffuse shedding, typically noticed two to four months after the change [1.3.4]. The hair loss is usually temporary and resolves within three to six months as the body adjusts [1.2.2].
- Androgenetic Alopecia For individuals with a genetic predisposition to female pattern hair loss, certain birth control pills can trigger or accelerate this condition [1.2.2, 1.6.6]. This is linked to the androgenic properties of some progestins used in the pills [1.2.4].
Understanding the Hair Growth Cycle
To grasp how birth control affects hair, it's essential to understand the hair growth cycle, which consists of three main phases:
- Anagen (Growth Phase): This is the active phase where hair grows. Estrogen is known to prolong this phase, which is why some women experience thicker hair during pregnancy or on certain types of birth control [1.2.3, 1.5.4].
- Catagen (Transitional Phase): A short phase where hair growth stops.
- Telogen (Resting Phase): The follicle is at rest. At the end of this phase, the hair is shed, and a new anagen phase begins [1.3.5]. Normally, only about 10-15% of hairs are in the telogen phase at any given time [1.3.5].
A sudden drop in estrogen (from stopping the pill) or the introduction of certain progestins can prematurely shift a large number of follicles into the telogen phase, causing noticeable shedding [1.3.1].
The Role of Progestin and the Androgen Index
The key factor determining a birth control pill's risk for causing hair loss is the type of progestin it contains and its "androgen index" [1.2.4]. Androgens are male hormones (like testosterone) that, in excess, can shrink hair follicles and shorten the growth phase, leading to thinner hair [1.2.2, 1.2.7]. Some synthetic progestins mimic these androgenic effects [1.2.5].
- High-Androgen Index Pills: These contain progestins with more testosterone-like activity, such as levonorgestrel and norgestrel [1.2.2, 1.2.5]. They are more likely to cause or worsen hair loss, especially in women with a sensitivity or genetic predisposition [1.2.2]. Other hormonal methods like injections (Depo-Provera) and some implants also have a higher androgenic effect [1.2.4].
- Low-Androgen Index Pills: These pills use progestins with low or even anti-androgenic effects, such as drospirenone, norgestimate, and desogestrel [1.2.5, 1.5.1]. Brands like Yaz, Yasmin, and Ortho Tri-Cyclen fall into this category and are less likely to cause hair loss; they are sometimes even prescribed to help manage it [1.2.2, 1.5.1].
Birth Control Pills & Hair Loss Risk Comparison
| Androgen Index | Common Progestins | Example Brands | Hair Loss Risk |
|---|---|---|---|
| Low | Drospirenone, Norgestimate, Desogestrel | Yaz, Yasmin, Ortho-Cyclen, Desogen, Mircette | Lower risk; may be prescribed to help with hair loss [1.2.5, 1.5.1]. |
| High | Levonorgestrel, Norgestrel, Norethindrone | Loestrin, Ovral, Nordette, Lo/Ovral | Higher risk, especially for those predisposed to hormonal hair loss [1.2.2, 1.4.2]. |
Hair Loss After Stopping Birth Control
It is common to experience temporary hair shedding, or telogen effluvium, about three months after discontinuing birth control pills [1.3.1]. This happens because the supportive estrogen from the pill is withdrawn, causing a hormonal fluctuation that pushes many hairs into the shedding phase at once [1.3.2]. This shedding is almost always temporary and should resolve on its own within about six to nine months as the body's natural hormone cycle resets [1.3.3, 1.3.6].
Other Causes of Hair Loss
If you experience hair loss, it's important to consider that birth control may not be the only cause. A doctor or dermatologist can help determine the root issue. Other common causes in women include:
- Stress (physical or emotional) [1.6.6]
- Nutritional Deficiencies (especially iron, zinc, and vitamin D) [1.6.4, 1.6.6]
- Thyroid Disease [1.6.2]
- Polycystic Ovary Syndrome (PCOS) [1.6.6]
- Other Medications [1.6.2]
- Recent Illness or Surgery [1.6.4]
Conclusion
Yes, birth control pills can cause hair loss, but the risk is not the same for everyone or every pill. The effect is primarily linked to hormonal fluctuations and the androgenic properties of the progestin in the pill [1.2.2]. For those concerned about hair loss, opting for a low-androgen index pill or non-hormonal birth control methods are safer choices [1.8.6]. Hair loss from starting or stopping a pill is often a temporary condition called telogen effluvium that resolves on its own [1.3.6]. However, if hair loss is severe or persistent, consulting a healthcare provider is crucial to rule out other underlying conditions and discuss appropriate management strategies [1.2.2].
For more information on hair loss, the American Academy of Dermatology Association is an authoritative resource.
