Types of Birth Control Pills: Monophasic vs. Biphasic vs. Triphasic

When it comes to birth control, your options are plentiful. Single-use forms like condoms are great to have on-hand, but many people also choose long-term methods like IUDs, implants, rings, or pills for added protection and peace of mind.

In the U.S., oral contraceptive pills are the most popular method of long-term birth control behind permanent sterilization.¹ Many people use them because they’re highly effective at preventing pregnancy,² and are easy to stop taking if you decide you want to get pregnant.

You might know oral contraceptives simply as “the pill,” though this nickname can apply to a few different medications. All contraceptive pills are taken by mouth and contain sex hormones that prevent pregnancy. But you may have heard other terms like combination, progestin-only, monophasic, biphasic, or triphasic pills to describe the range of oral contraceptive options.

The number of options for contraceptive pills may seem overwhelming, but understanding the difference between them is key to deciding which one is best for you. What works well for your body may not for someone else, and vice versa. Here, we’ll break down the categories of contraceptive pills on the market, and highlight what you should know about their benefits and risks.

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Types of birth control pills

All birth control pills use hormones to prevent pregnancy. But different pills contain varying proportions of estrogen and/or progestin (an artificial form of progesterone), the two hormones at work.

Estrogen and progestin do two main things to stop pregnancy before it starts. First, they prevent the ovaries from releasing an egg each cycle, nixing the opportunity for sperm to reach one. And in the event that an egg is released, these hormones alter cervical mucus and the uterine lining to further thwart fertilization and implantation.

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What are combination birth control pills?

There are two major varieties of birth control pills on the market: combination pills and progestin-only pills.

Progestin-only pills are also known as the “mini-pill” due to the fact that they only contain progestin.³ These pills contain lower doses of the hormone than any combination pill,⁴ and they come in comparatively fewer varieties.

Combination pills contain both progestin and estrogen.⁵ These types of hormones occur naturally in the body, but the pill uses man-made versions of progesterone and estrogen in order to prevent pregnancy.

There are many options for combination pills, as their dosage varies based on prescription – and so does the cycle on which you take them. Depending on your personal needs and preferences, some combination pill cycles might work better for you than others.

People taking the combination pill typically follow a 28-day cycle, where they take one active pill per day for 21 days, followed by a week of placebo pills. The placebo week is when people typically get their periods — technically, a “withdrawal bleed,” not a real period — due to a drop in hormones. (Comparatively, there is no placebo week for the mini-pill.)

The placebo week is when people typically get their periods.

On the combination pill, you can choose to take a hormonal pill every day and skip your period entirely, or follow an extended cycle. Some people will take the pill for 84 days (12 weeks), followed by a placebo week. This option can help stop scheduled bleeding that sometimes comes with the typical 28-day cycle.⁶

Monophasic vs. biphasic vs. triphasic birth control

Some combined birth control pills have different levels of progestin and estrogen every day, but others stay consistent throughout your cycle. Combination pills fall into three main categories:⁷

• Monophasic: These pills have the same amount of estrogen and progestin in each active pill.

• Biphasic: The amount of progestin in active pills changes once, splitting your cycle into two parts. In a 21-day active pill pack, the first half would have a lower amount of progestin than the second next half. However, the amount of estrogen remains consistent throughout the full cycle.

• Triphasic: Similar to biphasic pills, your cycle is split into portions due to a steady change in hormones. For triphasic pills, the amount of hormones changes twice, dividing a 21-day cycle into three even, seven-day phases.

Quadriphasic (four-phase) birth control is uncommon but also exists, as do 84-day extended regimens that also involve three phases (e.g. Rivelsa).

Both biphasic and triphasic pills are designed to mimic the natural hormonal fluctuations of your monthly cycle. Changing hormone levels doesn’t make these pills any less effective, and some people prefer them to monophasic pills due to the fact that they can be easier to adjust to.

But ultimately, your choice of birth control should be the one that is best for your body. Remember, you might prefer an option that your friends don’t, and that’s perfectly okay.

Benefits and side effects of combination oral contraceptives

There are some reasons why people prefer one type of birth control pill over another. If you’re deciding which one to try, it can help to look at the benefits and potential side effects of each kind.

Combination pills are the most common type of birth control pill on the market. In addition to their over-90-percent efficacy rate, they can provide additional benefits to preventing pregnancy. Many folks who take combination pills experience lighter and more regular periods and reduction of menstrual cramps. They can also be used to treat endometriosis and reduce the risks of developing uterine, ovarian, and colon cancer.⁸

Combination pills are the most common type of birth control pill on the market.

And when it comes to trying monophasic, biphasic, or triphasic combination pills, there are a few differences to consider. All three will offer the same protection against pregnancy when taken correctly, though you might find some easier to adjust to than others.

Because monophasic combination pills don’t mimic the hormone fluctuations of a regular menstrual cycle, you might find that they help alleviate certain hormonal symptoms, such as menstrual headaches. Some evidence shows that breast pain and swelling might be alleviated with triphasic pills, but side effects between pill types tend to be pretty similar overall.⁹

One downside with biphasic and triphasic pills is that it can be difficult to realign your cycle if you forget to take your pill for more than a day.¹⁰ Skipping even one dose can jeopardize the efficacy of your birth control. Monophasic pills also need to be taken every day, but are a little more forgiving if you forget a pill since the amount of progestin in each active pill doesn’t change.

However, combination birth control pills – no matter if they’re monophasic or multiphasic – can be risky for certain people. If you are a regular smoker or have a history of high blood pressure, they can especially increase your risk for blood clots, heart attack, or stroke.^5,8

Benefits and side effects of progestin-only pills

Progestin-only pills are a reliable option if you cannot or prefer not to take the combination pill. Since they contain no estrogen, they don’t come with the same cardiovascular risks, and can also be taken right after childbirth.¹¹

But like any medication, all types of hormonal birth control pills can cause side effects. Headaches, nausea, and breakthrough bleeding are especially common in the first few months of use.⁸ Many of these fade with time, but it’s important to keep an eye out for serious or uncomfortable side effects, especially if birth control pills interfere with your quality of life.

What kind of birth control is right for you?

Understanding the differences between contraceptive pills is the first step to finding one that is right for you. Some hormone levels, cycles, and phases might work better for your body than others, so it’s important to keep these differences in mind when choosing a new method. If your birth control is causing negative side effects, it might be time to switch birth control methods.

Want to learn which birth control is right for you? Get started with The Birth Control Test.