Go back

What Is a Progestin-Only Birth Control Pill?

Susan Vachon

Medically reviewed by Susan Vachon, PA-C on October 26, 2020

When you hear about birth control pills, you’re probably thinking about combination pills — pills that contain doses of both estrogen and progestin. Progestin-only birth control pills, also known as minipills, are an effective alternative to combination birth control pills that many women will find better suit their needs. 

If you’re thinking about adopting the minipill as your method of birth control, you’ll probably want to ask some questions first. Here are some of the most common: 

How does the minipill work?

The minipill, like all forms of hormonal birth control, works by altering the patterns of naturally-occurring hormones in the body. Birth control that contains both estrogen and progestin is made effective primarily by preventing ovulation; while progestin alone can interfere with ovulation, it doesn’t always do so consistently. 

Instead, the minipill thickens the cervical mucus, making it more difficult for sperm to enter, and thins the lining of the uterus, preventing any eggs that do become fertilized from attaching. Even though the minipill does not always prevent ovulation from occurring, it still works just as well as other birth control methods: when taken exactly as prescribed, it’s 99% effective, though that efficacy rate drops to 91% with regular use — meaning that 9 out of every 100 women who take the minipill will become pregnant each year. 

Who is the minipill for?

Unsurprisingly, the minipill is primarily intended for women who cannot or should not increase the natural levels of estrogen in their bodies. Estrogen can significantly increase the risk of developing blood clots; though most birth control contains doses of estrogen too small for this to be a serious factor, women with certain medical histories should choose progestin-only options instead. 

If you have high blood pressure or a pre-established medical history of blood clots, you should consider the minipill as your birth control method of choice — this is especially true of women who are over the age of 35 and smoke, who should not take estrogen. The minipill is also popular among women who are breastfeeding, as estrogen can interfere with the body’s production of milk, and in women who experience migraine with aura, who are at greater risk of stroke if they take estrogen. 

How do I take the minipill?

You can start taking the minipill as soon as you get it, but the day you start on will determine how soon after you’re protected from unwanted pregnancy. If you start taking the minipill within the first 5 days of your period, you’ll be protected immediately — otherwise, plan on using another form of birth control such as condoms for a week after you begin taking the minipill.

The most important thing to know about the minipill is that some brands, namely Norethindrone, must take it at the exact same time every day. If you miss a dose by more than three hours, you’ll need to use condoms or another form of birth control for at least 2 days after in order to let your body’s hormone levels get back to where they need to be. A second type of minipill, Slynd, must also be taken once a day but has the same dosage window as a combination pill. 

What are the side effects of the minipill?

Like all forms of hormonal birth control, there are some side effects associated with minipill use, such as:

  • Breast tenderness
  • Irregular periods
  • Depression
  • Headaches
  • Nausea

These side effects are rare, and those that do appear tend to go away after a few months of continuous use. The minipill can also produce some more serious complications, but generally only in women who are advised against taking it, such as:

  • Breast cancer survivors
  • Women with liver disease
  • Women with unexplained uterine bleeding
  • Women with lupus

As always, consult with your doctor about which birth control methods will interact best with your medical profile.

What are alternatives to the minipill?

Despite its popularity, the minipill is far from the only progestin-based method of birth control. Others include:

  • The birth control shot: the birth control shot is an injection of progestin administered to women every 3 months. It is as safe and effective as other forms of birth control and is a good option for women who don’t want to worry about birth control every single day. 
  • The birth control implant: the birth control implant is a small rod implanted directly into the arm that releases a steady dose of progestin throughout the body. The implant is a long-term birth control method: it can remain effective for several years after insertion, though it can also be safely removed at any time by a medical professional. 
  • The IUD: like the implant, the IUD is a progestin-containing device that can protect you from unwanted pregnancy for several years. It is inserted directly into the vagina, where it continuously releases small amounts of progestin. There are also hormone-free IUDs made of copper that are just as effective. 

If you’re looking for progestin-only birth control options, it can be difficult to know which path to take. Learn about which methods may be best for you by answering a few questions here.

Back to top