Progesterone-Only Contraceptives

Progesterone-only contraceptives are medications intended for use for those experiencing are painful periods, endometriosis-related pelvic pain, menstrual migraines, PMS (premenstrual syndrome), and menstrual cycle irregularities. Progesterone-only contraceptives contain a synthetic progesterone, a hormone that influences the female reproductive system. Progesterone-only contraceptives can increase the risk of developing ovarian cysts, ectopic pregnancy (pregnancy outside of the womb), and issues with liver functioning. Additionally, progesterone-only medications may increase the risk of developing certain cancers such as breast cancer.1-4

A laparoscopy (a minimally invasive surgical procedure) is the only method of definitively diagnosing endometriosis. Because of this, some providers may treat endometriosis-related symptoms empirically. This means that they are basing their treatment decisions on past experiences and other cases they have seen. If a woman comes in with clear signs of endometriosis, her provider may recommend a progesterone-only contraceptive for her pain instead of pursuing diagnostic surgery to see if her pain responds. This may lead to symptom and pain reduction without needing to undergo a procedure. Additionally, a woman may come in with signs of endometriosis who is also wanting to try birth control. Her provider may recommend a progesterone-only contraceptive to potentially address both issues.5

Progesterone-only contraceptives include progesterone-only birth control pills as well as the hormonal IUD (intrauterine device, Mirena), the birth control arm implant (Nexplanon), and the progesterone injection (also referred to as the birth control shot, Depo-Provera).4

What are the ingredients in progesterone-only contraceptives?

Each progesterone-only contraceptive contains a synthetically created progesterone hormone. Although the exact synthetic version may vary between each progesterone-only contraceptive, they all function in a similar manner, and behave like naturally produced progesterone in the body.2-4

How do they work?

Progesterone-only contraceptives affect the levels of progesterone in the body. Although this hormone is synthetically created in these medications, the body recognizes it in the same manner. Progesterone-only contraceptives decrease the chances of ovulation (the process by which the ovaries release an egg each month). This suppression of ovarian function helps stabilize natural hormone levels in the body, suppressing endometriosis lesion growth. The progesterone also thickens cervical mucus, limiting sperm mobility and their ability to reach any eggs that may have been released. Progesterone-only contraceptives may also lighten the menstrual cycle and reduce dysmenorrhea (pain during a woman's period). All of these mechanisms also suppress endometriosis lesion growth and shedding in other parts of the body, thus, reducing a woman's endometriosis-related pain.2-4

Progesterone-only contraceptives are not considered to be as effective in preventing pregnancy as combination contraceptives (which contain both estrogen and progesterone), however, progesterone-only medications may be the only hormonal birth control option for women who cannot take estrogen, including those who are currently breast feeding or who have a history of blood clots.2-4

Possible side effects

Many clinical trials have evaluated the safety and efficacy of progesterone-only contraceptives across their various methods of delivery (pill form, injection, arm implant, intrauterine device). The most common side effects reported are:

  • Unexpected bleeding or spotting
  • Changes in menstrual bleeding
  • Nausea
  • Breast tenderness
  • Headaches
  • Weight changes
  • Dizziness
  • Abdominal pain
  • Anxiety
  • Acne
  • Changes in sex drive4,6,7

These are not all the possible side effects of progesterone-only contraceptives. Talk to your doctor about what to expect or if you experience any changes that concern you during treatment with progesterone-only contraceptives.

Things to note about progesterone-only contraceptives

Progesterone-only contraceptives may increase a woman's risk of developing ovarian cysts, ectopic pregnancy (pregnancy outside of the womb), blood clots, cardiovascular complications, and issues with liver functioning. It's also possible that progesterone-only contraceptives may increase a woman's risk of developing breast cancer or other cancers within the female reproductive system. Women taking progesterone-only contraceptives may experience a decrease in bone mineral density, especially when using the progesterone-only contraceptive injection (the birth control shot). Talk with your provider about your individual risk profile to determine if progesterone-only contraceptives are right for you.4,6,7

Before starting a progesterone-only contraceptive, talk to your doctor if you:

  • Are taking any other medications, vitamins, or supplements
  • Have a history or blood clots or a family history of blood clots
  • Have any liver conditions
  • Have a personal history or family history of breast cancer or other cancers of the female reproductive system
  • Have any cardiovascular conditions
  • Are a smoker
  • Are allergic to any medications or ingredients in any medications
  • Could be pregnant
  • Have diabetes or are pre-diabetic4,6,7

Dosing information

The dosing information for a progesterone-only contraceptive will vary with the type of therapy used. The progesterone-only injection is administered by a medical professional once every three months, while progesterone-only pills are taken at the same time daily. The implant and the intrauterine device are inserted by a medical professional and may last up to three to five years until they need to be removed and replaced, if desired. Talk with your healthcare provider about the dosing schedule for your progesterone-only contraceptive. If you are taking progesterone-only pills daily, talk with your provider about what to do in the event that you miss one or multiple doses.

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Written by: Casey Hribar | Last reviewed: February 2021