Mini pill – how does this contraception work?

30th January, 2023 • 11 min read

Wondering if progesterone pills could be a good birth control option for you? Here’s what you need to know about the mini pill, from effectiveness and side effects to benefits – including how it can be helpful for women who can’t take pills containing estrogen.

What is the mini pill?

Unlike the combined pill, the mini pill doesn’t contain estrogen. It uses just 1 hormone – progestin, a form of progesterone. It’s also known as the progestin-only pill, or POP.

It stops you getting pregnant by:

  • thickening the mucus that’s released by the entrance to your womb (cervix) – which makes it more difficult for sperm to get inside and fertilize an egg
  • sometimes also stopping your ovaries from releasing an egg (ovulation)

You take a pill every day, with no break between packs of pills.

Types of mini pill

Which mini pill you can get will vary depending on what country you’re in, but the types include:

  • 3-hour (traditional) progestin-only pill – these have to be taken within the same 3 hours every day
  • 12-hour (desogestrel) progestin-only pill – these have to be taken within the same 12 hours every day
  • 24-hour progestin-only pill – this newer type of pill can be taken at any time, as long as you take 1 pill every day
Type of mini Pill 3-hour progestin-only pill 12-hour progestin-only pill 24-hour progestin-only pill
UK brand names Micronor, Norgeston, Noriday Cerelle, Cerazette, Hana, Lovima, Zelleta N/A
US Brand names Camila, Errin, Heather, Jencycla, Jolivette, Micronor, Nora-Be N/A Slynd

Mini pill effectiveness

If you take it correctly, the progestin-only pill is very effective at preventing pregnancy.

Here’s what you need to know:

  • it’s more than 99% effective with perfect use. This means taking it correctly every time, and never forgetting a pill or taking it late. When it’s used in this way, less than 1 in 100 women will get pregnant in a year (so more than 99 in 100 won’t)
  • it’s about 91% effective with ‘typical’ use. This means how it’s usually used in real life – for example, you may forget to take a pill, or take it later than the 3- or 12-hour window. When it’s used in this way, about 9 in 100 women will get pregnant in a year (so 91 out of 100 won’t)

Who is the mini pill suitable for?

“If you’re healthy and have no medical reasons for avoiding the progestin-only pill, you can take it until you reach the menopause, or until you’re 55,” says Dr Ann Nainan, family doctor and Healthily expert.

“Research suggests that about 0.4% of women aged 16-49 in the US use the progestin-only pill, and about 6% in the UK. So it isn’t as commonly used as some other types of contraception. But it’s worth asking your doctor about it if you think it might suit you.”

For example, the mini pill can be useful if you can’t – or don’t want to – take contraception that contains estrogen, such as the combined pill.

This might be because you:

Read more about [who shouldn’t take the combined pill](/health-library/drugs/combined-pill/#Who shouldn’t take the pill?).

Who shouldn’t take the mini pill?

Your doctor may advise you to avoid the mini pill if you:

  • will find it difficult to take the pill at the same time every day because of your work schedule or for other reasons
  • have had breast cancer
  • have unexplained vaginal bleeding
  • have liver disease
  • take medicines that affect liver enzymes, which can make the mini pill less effective. These include the antibiotics rifampicin and rifabutin, the herbal remedy St John’s wort and some medications used to treat epilepsy and HIV

What are the benefits of progesterone pills?

Possible advantages of the mini pill include:

  • you take them every day, so you may find it easier to get into a routine – unlike the combined pill, where you have a break between packs
  • they don’t interrupt of affect sex
  • you can take them if you need or want to avoid estrogen
  • you can use them when you’re breastfeeding
  • you may get less frequent or no periods – which some people prefer
  • they may help reduce symptoms of premenstrual syndrome (PMS) and painful periods
  • they don’t appear to cause weight gain

What are the mini pill disadvantages?

Possible downsides of the progestin-only pill include:

  • having to remember to take it at the same time every day – although with some types you get more flexibility
  • your periods may become irregular or stop – some people prefer to have regular periods
  • it doesn’t protect you from sexually transmitted infections (STIs) – if you want STI protection, you need to use condoms during sex

Progesterone pills side effects

Like any medicine, the mini pill can sometimes have side effects. “But the mini pill is generally well-tolerated by women who take it,” says Dr Ann. “And any side effects usually stop after a few months.”

Here’s what you need to know:

  • period changes are common – about 4 in 10 women on the mini pill have irregular bleeding, while 2 in 10 get no periods at all. These changes lead some women to stop taking mini pill – though 4 in 10 women still have regular periods
  • other side effects include spotty skin, breast tenderness and mood changes – these are less common, and usually ease off or go away after a few months
  • occasionally, the mini pill can cause small cysts on your ovaries – these usually aren’t serious, and often don’t cause any symptoms. In rare cases, if they grow large, they can cause lower tummy (abdominal) pain. So see you doctor if you have symptoms

How to get the mini pill

  • in the US, you’ll need a prescription from a doctor or nurse at your doctor’s office or a health clinic. In a few states, you can get a prescription online or from a pharmacist. “Talk to your health insurer about what they cover at no cost to you,” says Dr Ann. “Under the Affordable Care Act (Obamacare), most plans include birth control – but some only cover certain brands.” Your doctor may also be able to help you get your chosen contraception covered, or help you work out if you qualify for Medicaid or other government programs that can help you pay for contraception
  • in the UK, you can get contraception for free (even if you’re under 16) from contraception clinics, sexual health clinics, GP surgeries, some young people’s services and pharmacies
  • if you buy the mini pill online or from a pharmacist, make sure you check how to take it correctly (including when to start taking it). This can vary depending on your menstrual cycle and health, and the type of pill you’re taking

How to get the best from the mini pill

“Sticking to taking your pill as instructed will give you the best effectiveness,” says Dr Ann. Here’s what you need to know.

Starting the mini pill

There are different rules for different brands of pill, and when you start also depends on your cycle – so it’s best to check with your doctor.

But in general:

  • you can start taking it at any time in your cycle, if you’re sure you’re not pregnant
  • if you start taking it on the first day of your period, you’re protected straight away
  • if you start at any other time, you need to use another type of birth control – such as condoms – for protection for the first 2 days

Starting the mini pill after having a baby

  • if you start taking it up to 21 days after giving birth, you’re protected straight away
  • if you start it more than 21 days later, you need to use another type of birth control for the first 2 days

Starting the mini after an abortion or a miscarriage

  • if you start taking it 1 to 5 days afterwards, you’re protected straight away
  • if you start more than 5 days afterwards, you need to use another type of birth control for the first 2 days

Your mini pill effectiveness routine

  • take 1 pill every day
  • take it at the same time every day – to make it a habit that’s easier to remember
  • set yourself up to remember – choose a time in your daily routine that will help to jog your memory. “You could try linking taking your pill to an existing habit, such as brushing your teeth or taking the dog for a walk,” says Dr Ann. “And set a daily reminder on your phone, too”
  • go straight on to the next packet – when you come to the end of a pill packet, you don’t have a break (unlike with the combined pill). This means you keep taking your pill during your period (if you have one)

What to do if you forget to take a pill

Whether you need to use extra protection depends on which [type of pill](/sexual-health/mini-pill-how-does-this-contraception-work/#Types of mini pill) you’re taking and how soon you remember to take it.

Here’s what you need to know:

  • take the missed pill as soon as you remember, then continue taking the rest of your pills as normal
  • if you’re more than 3 hours late taking a 3-hour mini pill, you need to use extra protection for the next 2 days
  • if you’re more than 12 hours late taking a 12-hour mini pill, you need to use extra protection for the next 2 days
  • if you have unprotected sex after forgetting a pill, you may need emergency contraception. Contact your doctor, and tell them you’ve been taking the mini pill (not the combined pill) to help them recommend the best emergency contraception for you

What to do if you’re sick while taking the mini pill

If you vomit or have severe diarrhea within 2 hours of taking the mini pill, it probably won’t be effective.

You should continue taking your pills as usual, but also use another type of birth control while you’re ill, and for 2 days after you feel better.

What to do if you want to change to another type of contraception

It’s best to speak to your doctor, contraceptive nurse, sexual health clinic or pharmacist:

  • you can discuss why you want to change, in case they can help with any issues you’re having
  • “they can also talk through the range of options, to help you find the right birth control for you,” says Dr Ann
  • if you choose a different kind of pill or another type of hormonal contraception – such as the ring or patch – they’ll give you information about what to do. You may be advised to use condoms during the changeover, as your new method may take a short time to start protecting you
  • if you choose to switch to a barrier method of contraception – condoms or a diaphragm or cap – you can start using it straight away

When to see a doctor

It’s a good idea to talk to your doctor if you:

  • are thinking about starting to use the mini pill
  • have any health conditions that may mean the mini pill isn’t suitable for you
  • forget to take the mini pill and aren’t sure what to do, or need emergency contraception
  • think you’re getting mini pill side effects, such as acne, mood changes or headaches
  • get any vaginal spotting, bleeding between periods or bleeding after sex
  • want to discuss other contraception options, such as the copper IUD or implant

Your health questions answered

How often do I need to see a doctor or nurse?

“This will vary depending on the country you’re in and your health history, and what pill brand you’re taking and where you get it from,” explains Dr Ann. “When you first start the mini pill, you’re usually given a 3-month supply to see how it suits you. If you’re happy with it and want to keep taking it, you usually go back to your doctor or where you first got your pill from to get a new supply. You usually need to do this a couple of times a year.”

Important: Our website provides useful information but is not a substitute for medical advice. You should always seek the advice of your doctor when making decisions about your health.