(Updated June 2014)
Progestin-Only Oral Contraceptives
Two formulations are available: one contains 0.35 mg of norethindrone, the other contains 0.075 mg of norgestrel. The primary mechanism of action is thickening of the cervical mucus.
The efficacy of progestin-only pills is highly dependent on consistent use; it is critical that women take the pill at the same time (i.e., within 3 hours) every day. There is no placebo week with progestin-only pills.
Often called "mini-pills," progestin-only pills are a good contraceptive choice for women who cannot use estrogen.58
This method is highly effective, with a failure rate of 0.3 percent with perfect use and 9 percent with typical use.19
- The primary side effect of progestin-only oral contraceptives is irregular menstrual bleeding—spotting or breakthrough bleeding, amenorrhea, or shortened cycles.
- Irregular bleeding decreases in many users by cycle 12.
- Less common side effects include headache, breast tenderness, and dizziness.
Contraindications and Precautions
(unacceptable health risk if the contraceptive method is used)
(theoretical or proven risks usually outweigh the advantages of using the method)
- History of bariatric surgery with a malabsorptive procedure (e.g., gastric bypass)
- Ischemic heart disease or stroke (current or history of)—for continuing method
- SLE (positive for antiphospholipid antibodies or status unknown)
- Migraine with aura—for continuing method (i.e., if migraines worsen in a woman who is already using progestin-only pills)
- Breast cancer in the past; no evidence of disease for 5 years
- Severe cirrhosis
- Malignant liver tumor
- Certain antiretroviral and anticonvulsant medications (some are designated category 2)
- Rifampin or rifabutin therapy
Source: Reference 5
- Rapidly reversible
- Easy to use, start, and stop
- No associated nausea
- Lack of estrogen in progestin-only pills makes the method appropriate for smokers older than age 35, postpartum breastfeeding women, and others with contraindications to estrogen
- Provides protection against uterine and ovarian cancer, benign breast disease, PID
- Requires a prescription
- Adherence can be challenging; user must remember to take pill at same time daily
- Initial irregular bleeding
- No protection against STIs
- The progestin-only pill must be taken at the same time each day.
- If a pill is more than 3 hours late, a back-up method of contraception should be used for at least the next 48 hours.
- Patients using progestin-only pills should obtain emergency contraception in advance. (Note that patients who are less than 17 years old will need a prescription for EC.)
- A range of bleeding disturbances may occur with progestin-only pills—from amenorrhea to irregular, frequent, or prolonged bleeding.
- The irregular bleeding pattern is likely to improve within a few months of pill initiation.
- If bleeding is heavy or particularly bothersome, women should contact their health care provider.
- This method does not protect against STIs.