What does evidence say about combined vs. progestin-only pills?

COCs or POPs? Here are some things to consider when helping a patient pick a pill.

by Ashley Brant, DO, MPH

published 02/09/16

Combined oral contraceptive pills (COCs) remain the most common form of birth control in the U.S., but they’re not right for everyone. Some patients may be limited to progestin-only methods because of medical problems, while others may prefer progestin-only methods for their non-contraceptive benefits. By discussing the side effects and benefits of different kinds of pills with your patient, you can help her choose one that fits her life. Let’s take a closer look at the benefits and side effects of COCs and POPs.

Abnormal bleeding patterns

COCs are frequently used to treat dysmenorrhea and menorrhagia, especially when these symptoms are related to endometriosis or fibroids. COC use can lighten periods and improve anemia in patients with heavy periods. COCs can be used continuously by skipping the placebo pills. This means your patient avoids monthly withdrawal bleed but may have a higher chance of experiencing unexpected spotting. POPs can also be used to treat dysmenorrhea and menorrhagia, but they can cause irregular spotting, amenorrhea, or prolonged bleeding. In fact, abnormal bleeding is the most common reason for POP discontinuation. Abnormal bleeding patterns often improve or resolve after 3 months, so thorough counseling may improve POP acceptability and adherence. If irregular bleeding would bother your patient, POPs may not be the best option.

Weight gain

The research is clear: there is no link between weight gain and either POP or COC use. Migraines Patients who have migraines with aura should not take COCs because of a possible increased risk of stroke. For patients who have migraines without aura, COCs are safe but may increase the frequency or severity of menstrual migraines—especially during the placebo pill week. Continuous use of COCs or switching to POPs may decrease the frequency of migraines and other hormone-related headaches.


COCs have anti-androgen properties and therefore generally improve acne, hirsutism, and alopecia. Patients may notice a flare in their acne when they first start taking COCs, but this will usually resolve. POPs may make acne worse. Libido Libido is affected by many factors. Both POPs and COCs are associated with hormonal changes that may decrease libido, although some women will have increased libido when they’re not worried about becoming pregnant.

Cancer risk

While it’s not technically a side effect, your patients may have questions about cancer. Use of COCs is associated with a reduced risk of developing endometrial, ovarian, and colorectal cancer. Although POPs have not been studied as extensively, it appears that they offer some protection against cancers, too. In the past there was concern about an increased risk of breast cancer with COCs, but the newer low-dose pills have not been shown to increase breast cancer risk.

And the rest…

Other COC side effects include breast tenderness, mood changes, nausea, and bloating. Switching to a POP will likely resolve or improve these side effects. Regardless of which pill your patient chooses, ask if she’d be willing to use it for at least 3 months. Many side effects will resolve or stabilize in this time period. The benefits and side effects of the contraceptive patch and ring are similar to COCs, since both the patch and ring have estrogen plus progestin. With proper counseling, you can help your patient choose a method of birth control that will fit her life and body. Bedsider has tools to help her remember to take the pill each day and request timely refills.

Ashley Brant, DO, MPH is a third year resident in obstetrics and gynecology at Baystate Medical Center in western Massachusetts. She plans to pursue fellowship in family planning because she wants to improve access to comprehensive reproductive health care. When she's not busy at the hospital, she enjoys spending time with her husband, their adorable son, and their pups.
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