The progestogen-only (mini) pill explained
Reviewed by the My London Pharmacy clinical team, Michelle Chuku, Pharmacist Independent Prescriber
·29 July 2026
·8 min read
Quick answer
The progestogen-only pill, often called the mini pill, contains just one hormone — progestogen — and no oestrogen. It works mainly by thickening cervical mucus and, in some types, preventing ovulation. It suits many people who cannot or prefer not to take oestrogen, including while breastfeeding.
What is the mini pill?
The progestogen-only pill, widely known as the mini pill, is a daily contraceptive that contains a single hormone, progestogen, and no oestrogen. Progestogen is a synthetic version of progesterone, one of the hormones the body produces naturally as part of the menstrual cycle. Because it leaves out oestrogen entirely, the mini pill is a useful option for people who cannot take the combined pill — for example because they smoke and are over 35, have migraine with aura, have high blood pressure or a history of blood clots — as well as those who simply prefer to avoid oestrogen or have found it did not agree with them.
It is also suitable while breastfeeding and can be started soon after having a baby, which makes it a common choice in the weeks after birth. Some people move onto it as they get older, when the combined pill may no longer be recommended. Taken correctly, the progestogen-only pill is more than 99% effective, meaning fewer than one in a hundred people using it perfectly would become pregnant in a year, though in everyday use the figure is lower because pills are sometimes missed or taken late.
How it works
The mini pill works chiefly by thickening the mucus at the neck of the womb, the cervix, creating a barrier that makes it much harder for sperm to travel through and reach an egg. It also thins the lining of the womb, so that even if fertilisation occurred a pregnancy would be less likely to establish. These effects begin quickly once the pill is taken consistently.
Some types, particularly those containing desogestrel, add a further layer of protection by stopping ovulation in most cycles, so that often no egg is released at all. This is part of why desogestrel pills have become the most widely used type. Because the mini pill contains no oestrogen, it avoids the oestrogen-related risks associated with the combined pill, such as the small increase in the chance of blood clots. It does, however, have its own considerations, the most noticeable of which is a tendency to change bleeding patterns.
Types of mini pill
In the UK, most modern progestogen-only pills contain desogestrel, and these have largely become the standard choice. Hana is a desogestrel pill that is also available directly from pharmacies after a suitability check, while CERAZETTE 75MCG (DESOGESTREL) is another widely used desogestrel option prescribed in the same class. Older progestogen-only pills contain a different progestogen, such as norethisterone or levonorgestrel, and work mainly through their effect on cervical mucus rather than by reliably stopping ovulation.
The practical difference between the two groups is largely about the timing window and how they prevent pregnancy. Desogestrel pills are popular because they work partly by preventing ovulation and offer a slightly more forgiving window for taking them each day, which suits busy or changeable routines. A clinician or pharmacist can help you choose based on your daily pattern, your preferences and any previous experience with contraception, and it is straightforward to try a different type if the first does not suit you.
How to take it and the timing window
The progestogen-only pill is taken every day without a break — there is no pill-free week and no gap between packs, so when one pack finishes you start the next straight away. This is a key difference from the combined pill, and it means bleeding, when it happens, is not a scheduled monthly withdrawal bleed. Timing each dose is more important than with the combined pill, because the protective effect on cervical mucus wears off if a dose is delayed too long.
Desogestrel pills such as Hana should be taken within a 12-hour window each day, while older progestogen-only pills have a stricter three-hour window. If you take a pill outside its window, it counts as a missed pill, and you may need to use extra precautions such as condoms for the next two days while protection re-establishes. Taking the pill at a consistent, memorable time — linked to something you do every day, and backed up by a phone reminder — is the simplest way to keep protection reliable. When you first start, you may need additional contraception for the first couple of days depending on where you are in your cycle, and the patient information leaflet will confirm exactly when you are protected.
What affects how well it works
Taken perfectly, the mini pill is more than 99% effective, but a few everyday situations can reduce that protection, and it helps to know them in advance. The most common is simply taking a pill late or missing one, which is why the timing window matters so much. Severe vomiting, or very watery diarrhoea that continues for more than a day, can stop the pill being absorbed properly, in which case it should be treated much like a missed pill until things settle.
Some other medicines can interfere with the progestogen-only pill and make it less reliable, including certain medicines used for epilepsy, some treatments for tuberculosis or HIV, and the herbal remedy St John's Wort. It is always worth mentioning that you take the mini pill when starting any new medication, and asking a pharmacist if you are unsure. If you have had unprotected sex during a time when protection may have been reduced, emergency contraception may be worth considering, and a clinician or pharmacist can advise. The mini pill protects against pregnancy but not against sexually transmitted infections, so condoms remain important where that is a concern.
Who it suits and side effects
The mini pill suits a wide range of people, including those who cannot take oestrogen, those who are breastfeeding, and those approaching the menopause. The most common effect is a change in bleeding pattern, and this is worth expecting from the outset: periods may become irregular, lighter, more frequent, or stop altogether. Roughly speaking, some people find bleeding settles into a lighter or absent pattern, while others have unpredictable spotting, particularly in the first few months as the body adjusts. None of these patterns is harmful, but the unpredictability can be unsettling if you are not prepared for it.
Other possible side effects include breast tenderness, headaches, mood changes, changes in sex drive and, occasionally, acne, and these often ease with time. Persistent or troublesome side effects are worth reviewing, as switching to a different pill sometimes helps. As with any contraception, a short assessment of your health and medical history helps confirm it is a suitable choice for you before you start, and gives you the chance to ask about anything that concerns you.
Missed pills and switching
If you miss a progestogen-only pill or take it late — beyond the 12-hour window for desogestrel pills, or three hours for older types — take one as soon as you remember, even if that means taking two pills in a day, then carry on as normal and use extra contraception such as condoms for the next two days. If you have had unprotected sex during that time, emergency contraception may be needed, and it is better to check than to assume you are covered. The patient information leaflet gives specific advice for your particular pill.
Many people switch between methods over their lifetime as their circumstances and priorities change, and moving between the mini pill and the combined pill, or the other way round, is usually straightforward with the right advice on timing so that you stay protected during the changeover. Whether you are starting contraception for the first time, switching from another method, or reviewing whether the mini pill still suits you, our clinical team can help through a discreet online consultation, and NHS sexual health and GP services also provide contraception free of charge.
Getting started and reviewing your choice
Starting the progestogen-only pill involves a short, straightforward assessment rather than anything elaborate. A clinician will ask about your general health, any medicines you take, your medical and family history, and what you are looking for from contraception, to confirm the mini pill is a safe and sensible fit. Because it contains no oestrogen, it is suitable for many people for whom the combined pill is not, which is one reason it is so widely used.
The mini pill is a fully reversible method: when you stop taking it, your natural fertility returns without delay, although it can take a little time for your own cycle to re-establish its usual rhythm. It is worth reviewing your contraception from time to time, especially if your health changes, if side effects are bothering you, or if your needs shift — for instance around breastfeeding, or as you move towards the menopause. A brief consultation is enough to check that your current method is still the best one for you, or to plan a smooth switch to something that suits you better.
Frequently asked questions
What is the difference between the mini pill and the combined pill?
The mini pill contains only progestogen and no oestrogen, while the combined pill contains both. This makes the mini pill suitable for people who cannot take oestrogen.
Can I take the mini pill while breastfeeding?
Yes. The progestogen-only pill is considered safe while breastfeeding and can be started shortly after having a baby.
What happens to my periods on the mini pill?
Bleeding often changes — periods may become irregular, lighter, more frequent, or stop. This is common and not harmful, though it can be unpredictable at first.
How late can I take the mini pill?
Desogestrel pills such as Hana allow a 12-hour window, while older progestogen-only pills must be taken within three hours of the usual time.
Can other medicines stop the mini pill working?
Some can, including certain epilepsy, tuberculosis and HIV medicines and St John's Wort. Mention that you take the mini pill when starting anything new, and ask a pharmacist if unsure.
Is the mini pill as effective as the combined pill?
Yes. When taken correctly, the progestogen-only pill is more than 99% effective, similar to the combined pill.