What is the difference between the mini pill and the combined pill?

The mini pill (progestin-only pill) contains only a progestin and no estrogen, while the combined pill contains both an estrogen and a progestin. Removing estrogen makes the mini pill an option for people who should avoid estrogen — such as those breastfeeding, with a history of blood clots, or who smoke and are over 35 — but it usually requires more precise daily timing.

Is Opill really available without a prescription?

Yes. In July 2023 the FDA approved Opill (norgestrel 0.075 mg) for over-the-counter use, making it the first daily oral contraceptive available in the U.S. without a prescription; it reached shelves in 2024. It is still a progestin-only pill and must be taken at the same time every day, and it does not protect against sexually transmitted infections.

How effective is the progestin-only pill?

With perfect use it is highly effective, but typical-use failure rates for the pill are estimated at around 7 percent per year, mostly because of missed or late doses. Taking it at the same time each day is the single most important factor. Drospirenone (Slynd) has a more forgiving missed-pill window than traditional norethindrone mini pills.

Why does the mini pill cause spotting?

Changes in bleeding are the most common and expected effect of progestin-only pills. Some people get irregular spotting, some have lighter or absent periods. This reflects how the progestin thins the uterine lining and is not usually dangerous, though it is the most frequent reason people stop the pill. New, heavy, or persistent bleeding should be evaluated by a clinician.

Can I use the mini pill during perimenopause?

Because it has no estrogen, a progestin-only pill can be an option for contraception during perimenopause, including for people who smoke or have other reasons to avoid estrogen. It does not treat hot flashes or replace menopausal hormone therapy, and by stopping periods it can make it harder to know when menopause has occurred, so the timing of stopping contraception is a clinician-led decision.

Contraception · Perimenopause

The progestin-only pill (mini pill): a plain-language guide

Educational guide · Updated July 2026 · By the ClearHormones Editorial Team

The progestin-only pill — often called the "mini pill" — is a daily contraceptive that contains a progestin but no estrogen. That single difference makes it an option for people who cannot or prefer not to take estrogen, from those breastfeeding a newborn to smokers over 35. This guide covers the main types available in the U.S., who they tend to suit, how well they work, the bleeding changes to expect, and why they come up so often in the perimenopause conversation.

Key takeaways

Progestin-only pills (POPs) contain no estrogen, which makes them suitable for many people who should avoid estrogen — including those breastfeeding, with a history of blood clots, with migraine with aura, or who smoke and are over 35.
U.S. options include norethindrone (traditional mini pills), drospirenone (Slynd), and norgestrel (Opill), which the FDA cleared for over-the-counter sale in 2023 — the first daily oral contraceptive available without a prescription.
Traditional norethindrone pills have a narrow daily window and must be taken at about the same time each day; drospirenone (Slynd) has a longer window and a more forgiving missed-pill rule.
The most common side effect is a change in bleeding — irregular spotting, lighter periods, or no periods at all — which is expected and not dangerous, though new or heavy bleeding should be checked.

What is a progestin-only pill?

A progestin-only pill is a daily birth control pill that contains a synthetic progestogen (a progestin) and no estrogen. Combined pills use both an estrogen and a progestin; the mini pill drops the estrogen entirely. It prevents pregnancy mainly by thickening cervical mucus so sperm cannot pass, and — depending on the specific progestin and dose — by suppressing ovulation.

Three kinds are used in the United States. Traditional mini pills use norethindrone (also spelled norethisterone) and work largely through cervical mucus, so their timing matters. Drospirenone, sold as Slynd, is a newer progestin-only pill that more reliably suppresses ovulation and has a more forgiving schedule. And norgestrel, sold as Opill, is the same well-studied progestin that has been used in oral contraceptives for decades — now available over the counter.

Opill: the first over-the-counter birth control pill

In July 2023, the U.S. Food and Drug Administration approved Opill (norgestrel 0.075 mg) for over-the-counter use, making it the first daily oral contraceptive available in the U.S. without a prescription. It reached store and online shelves in 2024. That is a genuine, citable milestone: for the first time, a person can buy a daily birth control pill the way they buy other over-the-counter medicines, with no clinician visit required.

Over-the-counter access lowers a real barrier, but Opill is still a progestin-only pill with the same timing discipline and bleeding changes as other mini pills. The FDA label directs people to take it at the same time every day and to use a backup method if a dose is late. It is meant for contraception, not for menopausal hormone therapy, and it does not protect against sexually transmitted infections.

Who the mini pill tends to suit

The progestin-only pill is often chosen precisely because it has no estrogen. That makes it a common recommendation while breastfeeding, since estrogen can affect milk supply and the postpartum period already carries a higher clot risk. It is also frequently used by people who should avoid estrogen for medical reasons: a personal history of venous thromboembolism (blood clots), migraine with aura, uncontrolled high blood pressure, or being a smoker over the age of 35, where combined pills are generally discouraged.

It is worth being precise about the clot point rather than overstating it. A meta-analysis in the BMJ found that, overall, progestin-only contraception was not associated with a significantly increased risk of venous thromboembolism compared with non-use — one reason POPs are considered an estrogen-free alternative for people at higher clot risk. As always, whether a mini pill is appropriate for you is a clinical judgment based on your full history.

How well does it work?

With perfect use, progestin-only pills are highly effective, but real-world "typical use" is what matters for most people. National estimates put the typical-use failure rate for the pill (both combined and progestin-only) at around 7 percent per year — meaning about 7 in 100 users would have an unintended pregnancy over a year — driven largely by missed or late pills. Perfect, consistent use lowers that considerably.

Timing is the practical difference between products. Traditional norethindrone pills have a roughly three-hour window: taken more than about three hours late, they call for a backup method. Drospirenone (Slynd) was studied as having a longer 24-hour missed-pill window, which many people find easier to manage. Whichever you use, taking it at the same time each day is the single biggest factor in how well it works.

Bleeding changes and other side effects

The most common and expected effect of a progestin-only pill is a change in your bleeding pattern. Some people get irregular spotting, some get lighter or less frequent periods, and some stop bleeding altogether. None of these is inherently harmful, but unpredictable spotting is the most frequent reason people stop the mini pill, so it helps to know it is normal and often settles over the first few months.

Other reported side effects can include headaches, breast tenderness, mood changes, and, less commonly, ovarian cysts. New, heavy, or persistent bleeding, or bleeding that concerns you, should always be evaluated rather than assumed to be a harmless side effect — especially in the perimenopausal years, when other causes of abnormal bleeding become more common.

The perimenopause angle

Perimenopause is a common reason the mini pill comes up in midlife. Because it contains no estrogen, a progestin-only pill can be an option for contraception into the mid-to-late 40s and beyond for people who smoke or have other reasons to avoid estrogen — a group for whom combined pills are often not advised. It can also help steady erratic perimenopausal bleeding for some users, though it does not treat hot flashes or replace menopausal hormone therapy.

One nuance to understand: because a mini pill can stop your periods, it can mask the natural cycle changes that signal menopause, making it harder to know when you have actually reached menopause and can stop contraception. Clinicians use age and, sometimes, hormone testing to guide that decision. If you are trying to make sense of changing perimenopausal periods, our dedicated explainers below are a good place to start — and the timing of stopping any contraceptive is a conversation to have with your clinician.

A note on choosing a method

Prescription progestin-only pills like Slynd, and the choice between contraceptive options in general, are clinical decisions based on your full history. This page is informational and does not recommend a specific product or dose. If you are weighing contraception alongside perimenopausal symptoms, our perimenopause explainer and the progesterone monograph add useful context.

Affiliate link Advertiser Disclosure: This site is reader-supported. We may earn an affiliate commission when you sign up for a service through links on our site. This does not influence our editorial recommendations or medical reviews. Read our full disclosure.

Frequently asked questions

What is the difference between the mini pill and the combined pill?: The mini pill (progestin-only pill) contains only a progestin and no estrogen, while the combined pill contains both an estrogen and a progestin. Removing estrogen makes the mini pill an option for people who should avoid estrogen — such as those breastfeeding, with a history of blood clots, or who smoke and are over 35 — but it usually requires more precise daily timing.
Is Opill really available without a prescription?: Yes. In July 2023 the FDA approved Opill (norgestrel 0.075 mg) for over-the-counter use, making it the first daily oral contraceptive available in the U.S. without a prescription; it reached shelves in 2024. It is still a progestin-only pill and must be taken at the same time every day, and it does not protect against sexually transmitted infections.
How effective is the progestin-only pill?: With perfect use it is highly effective, but typical-use failure rates for the pill are estimated at around 7 percent per year, mostly because of missed or late doses. Taking it at the same time each day is the single most important factor. Drospirenone (Slynd) has a more forgiving missed-pill window than traditional norethindrone mini pills.
Why does the mini pill cause spotting?: Changes in bleeding are the most common and expected effect of progestin-only pills. Some people get irregular spotting, some have lighter or absent periods. This reflects how the progestin thins the uterine lining and is not usually dangerous, though it is the most frequent reason people stop the pill. New, heavy, or persistent bleeding should be evaluated by a clinician.
Can I use the mini pill during perimenopause?: Because it has no estrogen, a progestin-only pill can be an option for contraception during perimenopause, including for people who smoke or have other reasons to avoid estrogen. It does not treat hot flashes or replace menopausal hormone therapy, and by stopping periods it can make it harder to know when menopause has occurred, so the timing of stopping contraception is a clinician-led decision.

Primary medical sources

ClearHormones publishes editorial health information for education only — not medical advice.