The "Mini-Pill" or Progestin-Only Contraceptive

What are progestin-only oral contraceptives?

Progestin-Only Pill (POP), commonly called the "mini-pill," is different from combined birth control pills in that they contain only one hormone (progestin) instead of two (progestin and estrogen).

How does the progestin-only pill work?

POPs may prevent pregnancy in several ways. They thicken the cervical mucus (the substance at the opening of the uterus), making it harder for sperm to reach and fertilize the egg. Like combined pills, they can prevent a woman's body from releasing an egg during her monthly menstrual cycle. However, ovulation may not be consistently suppressed on POPs. Five percent of women using POPs will have an unintended pregnancy within the first year of typical use. Perfect use rate is 0.5%. The chance of becoming pregnant increases with missed pills. While the overall risk of ectopic (tubal) pregnancy is lowered by this method, any pregnancy that does occur is more likely to be ectopic. Finally, POPs will not prevent functional ovarian cysts as well as the combination oral contraceptive.

Why would a woman choose a progestin-only pill?

POPs do not contain estrogen. Therefore they can be used by women who cannot or should not use combined oral contraceptives, such as women with a history of blood clots, migraine headaches with aura, high blood pressure, or cigarette smokers over the age of 35. Women who are breast-feeding can use POPs for contraception. Using POPs while breastfeeding will not harm a baby and may actually help increase the amount of milk produced. POPs have a number of noncontraceptive benefits. They decrease menstrual blood flow and cramping, reduce risk of anemia and endometrial cancer, and reduce risk of pelvic inflammatory infection; however, they do not protect against sexually transmitted diseases (STD’s). POPs offer reversibility. Ovulation is reestablished quickly after discontinuation. POPs do not cause infertility.

How are the progestin-only pills taken?

It's best to start the pills during the first five days of your period or on any day you are reasonably sure that you are not pregnant. The pill is taken every day at the same time. There are NO placebo or "sugar" pills. It is important to take the progestin-only pill at the same time every day. Varying the time by even a few hours greatly increases the risk of becoming pregnant. Use a back-up method or abstain for the first 48 hours.

How often are pop taken?

If you are switching from COC to POP, start the first pill on the first day of the inactive week (No break between methods.)

What if pills are missed or taken late?

If you are three or more hours late or you miss one POPs; take the missed pill as soon as you remember that you missed it; THEN go back to taking your POPs at your regular time. Be sure to use a backup method (such as condoms and/or spermicide) every time you have sex for the next 48 hours. If you miss two or more POP's in a row; restart your POP's right away and take two pills a day for two days. "Be" sure to use a backup method for the next seven days. If you miss two POP’s in a row there is an increased risk of pregnancy. Immediately start using a back-up method. If your period does not begin in 4-6 weeks, pregnancy testing is advised. Pregnancy tests are available in the Health Resource Centers or over-the-counter.

If you have missed pills or been three or more hours late taking the POP and had intercourse without a back-up method you may be able to use an emergency contraceptive. ECP is available over-the-counter.

What are the side effects?

The most common side effect is irregular bleeding or spotting. In most cases, the bleeding is not serious and will stop in less than eight days. If you have a fever, abdominal pain or heavy bleeding, contact your health care provider. Less common side effects include headache, nausea, acne, weight gain or loss, and breast tenderness. If you have a severe headache or worsening of a migraine, contact your provider.

Are there any medications that affect the pop?

The effectiveness of POPs is reduced by the anticonvulsants phenytoin, carbenzemide, and barbituates, and the antituberculosis antibiotic rifampin, St. John’s Wart and no significant interaction has been found with broad-spectrum antibiotics.

How do I get a pop prescription?

First time hormone users need to complete the on-line birth control class and quiz by visiting McKinley Health Center’s main web page at: www/ You then need to click the On-line Classes, Programs and Services hyperlink and then click on the On-line Birth Control Class hyperlink. All hormonal contraceptive users must have had an annual exam done within the year by a McKinley or outside healthcare provider. Outside prescriptions may be taken or faxed to the pharmacy.


Ortho McNeil Pharmaceutical, Inc.
RA Hatcher et. al Contraceptive Technology 19th ed. 2007
Ardent Media, Inc., New York