Can you get pregnant on the pill?

can you get pregnant on the pill
What can effect your contraceptive pill?

Although the pill has a high success rate, there are various factors that can disrupt this. From vomiting to certain medications they can all play a part in the effectiveness of your pill.

If you want to know exactly what to avoid to ensure your contraceptive pill remains effective as possible, then keep reading.

How does the pill work?

There are two types of contraceptive pill:

Combined pill:

(Examples being Yasmin, Rigevidon and Levest)

The combined pill is a hormonal contraceptive in the form of a small tablet you take daily. It contains the hormones oestrogen and progesterone. It works to prevent pregnancy in three ways –

  1. Stopping ovulation
  2. Making the fluid in your cervix thicker (which makes it more difficult for sperm to enter the womb)
  3. Prevent the lining of your womb thickening enough for an embryo to grow in it

Mini Pill:

(Examples being Aizea, Cerelle and Zelleta)

The Mini pill (also known as Progesterone only pill POP) is a small tablet you swallow daily, and unlike the combined pill, only contains one hormone – progesterone. It prevents pregnancy in the same way as the combined pill.

How effective is the contraceptive pill?

The birth control pill is 99% effective if taken correctly, meaning you do not miss any pills. This means that 1 out of 100 women who take the pill would become pregnant in 1 year. However, according to typical use, the effectiveness of the pill is just 91%, which means that around 9 in 100 women would become pregnant in a year of taking the pill.

What happens if you miss a pill?

If you miss a pill there are certain actions you must take. If you have missed 2 or more pills your protection against pregnancy may be affected. 

What you should do:

  • Take the last pill you missed, even if this means taking 2 pills in 1 day
  • Leave any earlier missed pills
  • Carry on taking the rest of the pack as normal
  • Be sure you use extra contraception, such condoms for the next 7 days

When you come to the end of your pill pack, after missing 2 or more pills: 

If there are 7 or more pills left in the pack after the last missed pill – finish the pack, take your 7-day pill-free break as normal, or take your inactive pills before you start your next pack

If there are less than 7 pills left in the pack after the missed pill – finish the pack and start a new pack the next day; this means missing out the pill-free break or not taking your inactive pills. 

Bear in mind that you may also need emergency contraception if you have missed 2 or more pills in the first week of a pack and had unprotected sex in the previous 7 days. 

What medications interfere with the pill?

Certain types of medication can make the pill less effective. Certain antibiotics, such a rifampicin, and anti-fungal drugs, such as griseofulvin. Whilst on these medications you should use backup contraception as well as for 48 after finishing the course. 

Other more long-term medications and supplements may also affect how well birth control pills work:

  • Epilepsy drugs such as phenobarbital, phenytoin and carbamazepine
  • Antiviral medications used to treat HIV 
  • St. John’s Wort, which is a herbal remedy

What can cause the birth control pill to fail?

Missing a day

The pill should be taken daily for it to be most effective and therefore if you miss a day, your hormone levels may not remain consistent enough to prevent pregnancy. If you struggle to remember to take a pill every day, other birth control methods may be best for you – check out our reviews from users to see which one is best for you. 


If you happen to become ill when taking the pill and vomit, the pill may not fully absorb into their body. If you do experience vomiting you should take another pill as soon as possible then take your next pill as usual.

Not taking the pill at the same time each day

The birth control pill is designed to be taken at or around the same time each day to ensure that it can maintain the hormones levels. You should also take the Mini pill within the same 3 hour time window every day. If you miss this you should use a backup birth control method for the next 2 days, or abstain from having sex. 

Not starting a new pack straight away

It is essential to start a new pack of pills the day after finishing the previous one. Missing a few days between packs can make the pill less effective at preventing pregnancy. If you miss two or more pills in a row you should use a backup contraceptive method until you have taken the birth control pill for 7 consecutive days.

How to prevent birth control failure?

Some tips for preventing birth control failure:

  • Reading the packaging and following the instructions carefully
  • Taking the pill at the same time every day
  • Using an app that tracks periods and provides pill reminders, check out Natural Cycles
  • Always getting a new pill pack at least 1 week before the pill pack is due to run out
  • Always take missed pills as soon as possible
  • Use a backup method of contraception if you miss taking 2 or more pills in a row. 

This guide was brought to you by The Lowdown. We are the world’s first contraception review platform, providing real-life experiences from thousands of reviews collected from our community of men and women.

Why not leave us a review of your contraceptive experience? Whether you’ve got good things to say about the Mirena coil or had trouble with implant removal, we want to hear about it! Tell us about your experience and help people around the world find the right method for them.