Endometriosis is a disease where tissue resembling the endometrium (the inner lining of the uterus) grows in other parts of the body. It most commonly occurs in the pelvic region. Like the endometrium found in the uterus, this tissue also responds to female sex hormones, estrogen, and progesterone, which play an important part in the menstrual cycle. Doctors often prescribe combined oral contraceptive (COC) pills to regulate the menstrual cycle as well as the symptoms of endometriosis.
Why are COCs not ideal for managing endometriosis?
Doctors have prescribed combined oral contraceptives (COCs) for many years for the symptomatic management of endometriosis despite the lack of concrete evidence of efficacy.
Endometriosis is an estrogen-dependent disorder. Estrogen given unopposed (without progesterone) can promote the growth of endometrial tissue leading to inflammation and pain. The COC contains both estrogen and progestin (the synthetic form of progesterone), which counters the effects of estrogen. COCs may help with painful symptoms of endometriosis. However, researchers think that estrogen dominance (estrogen having a greater effect than progesterone) may still occur when taking COCs. Therefore, they will not help with regression of endometriosis lesions and in some cases with continuing progression of the disease.
COCs are also limited in their applicability. They are not suitable for women over age 35 who smoke, those at increased risk of stroke, heart attack, and blood clots. They are also not suitable for women who are taking certain medications.
Which birth control pills are more effective?
Research suggests that progestin-only pills are a better alternative to COCs to manage the symptoms of endometriosis. This is because they do not contain estrogen.
The continuous administration of progestins at higher doses than the COC also stops regular periods and reduces the chances of breakthrough bleeds. Progestins also have anti-inflammatory properties, which is helpful in alleviating inflammation and pain associated with endometriosis.
Finally, another advantage of progesterone-only pills is that they can be used at any age to stop menstruation. They also have fewer side effects and cause no risk of internal clots.
Please note that the “mini-pill”, while progestin-only, is only a contraceptive pill that works by thickening cervical mucus. It may not help to the same extent with pain symptoms and also does not suppress the menstrual cycle or stop ovulation. The mini-pill is at a dose that is 10 times lower than progesterone-only therapies for endometriosis.
What are some of the progestin-only treatments available?
Progestin-only treatments are available as pills, injections, and intrauterine devices.
Norethindrone and medroxyprogesterone are oral pills and medroxyprogesterone are also available as an injection.
Progesterone pills are usually taken daily and at the same time every day. On the other hand, injections are given once every three months.
Levonorgestrel is another progestin that is available both as a pill and as a small, T-shaped intrauterine device. The device can release medication for up to five years.
What other hormone therapies are available?
Danazol is a synthetic male hormone or androgen that can also help manage endometriosis. It lowers estrogen levels and prevents the growth of endometrial tissue. However, its use is no longer common. This is because of the risk of severe side effects including weight gain, changes in menstrual cycles, and other androgenic effects such as excess hair growth in a male pattern.
Leuprolide acetate (leuprorelin, or Depo Lupron) is an injection that women receive every one or three months to treat endometriosis. Leuprolide interferes with the signaling that tells the ovaries to make estrogen. It, therefore, lowers natural estrogen levels inhibiting the growth of endometriosis. Essentially, it tells the brain to stop sending messenger hormones (follicle-stimulating hormone and luteinizing hormone, FSH and LH) to the ovaries. In other words, it creates a state of pseudo-menopause. However, the continuous administration of leuprorelin can lead to side effects such as hot flashes, vaginal dryness, and low bone mineral density with a risk of fracture. Therefore, doctors often supplement leuprorelin with hormonal “add-back” therapy in which they prescribe a progesterone pill alongside to offset the side effects and prevent endometriosis progression at the same time.