How long does the pill take to work?

How long the pill takes to work depends on which type of pill you take and which day in your menstrual cycle you start taking it. Other things can affect how long it takes too, such as if you have just given birth. You should seek advice from your nurse or doctor if you have a short or irregular menstrual cycle or if you’re not sure whether your pill is working.

Combined pill

If you start the combined pill on day 1 of your menstrual cycle (which is the first day of your period) up until day 5, it will work straight away. This means you are protected from pregnancy immediately.

If you start the combined pill after the 5th day of your menstrual cycle, it will take a week to work. You should use additional protection or avoid sex until you have taken the combined pill for 7 days in a row.

After giving birth:

You can usually start taking the combined pill 21 days after giving birth if you are not breastfeeding, but this can depend on other risk factors. It’ll start working straight away.

If you are breastfeeding, the combined pill can be started 6 weeks after giving birth. It will take 7 days for the pill to start working. It’s important to remember that the pill only protects you from pregnancy and not STIs, so you may still want to use a form of barrier contraception like condoms.

Mini pill

Starting the mini pill on days 1 to 5 of your menstrual cycle means it will start working straight away. However, if your menstrual cycle is shorter than 28 days, it can take 2 days for the mini pill to start working. You should use additional contraception or avoid sex until then.

If you take the mini pill after day 5 of your menstrual cycle, it will take 2 days to work.

After giving birth:

After having a baby, you can start the mini pill the day after birth up until day 21, and it will work straight away. If it has been longer than 21 days since giving birth, it will take 2 days for the mini pill to work.

The pill works by changing your natural hormone levels to prevent ovulation (when a mature egg is released from your ovary). Depending on what day you take the pill, it may take a few days (usually 2 to 7) for the hormones to prevent ovulation, meaning you can still get pregnant.

You will be protected from pregnancy as long as you keep taking the pill every day and on time. If you use a combined pill and take a break between pill packs, you are still protected from pregnancy as long as you:

• have taken your pills correctly
• start your next tablet pack on the correct day

If you miss a pill, this can make it less effective, and you may not be entirely protected from pregnancy.

Missing a pill or multiple pills will make it less effective, but you may still have some protection depending on the pill.

If you take the combined pill and miss:

• 1 pill, or start 1 day late after your break, you will still be protected. If this happens, take the last pill as soon as you remember, even if you have to take 2 pills in a day.
• more than 1 pill, it will become less effective. You should use another form of protection for 7 days and may need emergency contraception if you’ve had unprotected sex.

If you take the mini pill and miss:

• a 3-hour mini pill but remember to take it within 3 hours of when you usually take it, you will still be protected.
• a 12-hour pill, but remember to take it within 12 hours of your usual time, you will still be protected.

The pill is over 99% effective at preventing pregnancy when taken correctly. However, this is reduced by things like forgetting to take your pill or getting diarrhoea and vomiting after taking a pill.

When taken correctly, the pill is more effective than female diaphragms, which are between 92% and 96% effective when used correctly, and female condoms which are only 95% effective.

However, the pill is not effective at preventing sexually transmitted infections (STIs), so it’s best to use a condom when you have sex.

This depends on which pill you are taking and how long it has been since it was due. You should still be protected from pregnancy if you only miss 1 combined pill, as long as you take it before your next dose is due.

When taking the mini pill, you will be protected as long as it is less than 3 or 12 hours since your last pill, depending on whether you take the 3 or 12-hour mini pill. If you aren’t sure, check your patient information leaflet or seek advice from your doctor.