Can Diarrhea Cause Birth Control To Fail (2025)

Diarrhea can significantly impact the effectiveness of oral birth control pills. Oral contraceptives work by altering hormone levels, preventing ovulation and preventing pregnancy. The pill is typically over 99 percent effective. Chronic diarrhea can also hinder absorption, making it unnecessary to take another dose. The Mayo Clinic advises that if you have experienced serious diarrhea or vomiting for two or more days, you should act as though you are taking a different medication.

In situations where combined hormone oral birth control pills contain both estrogen and hormones, certain medications like antibiotics, anticonvulsants, and St. John’s Wort can make the pill less effective. Prolonged vomiting or diarrhea can prevent the pill from working properly. If you experience vomiting or severe diarrhea for less than 48 hours (2 days) after taking a dose, you generally don’t need to repeat the dose. However, other factors such as not taking the pill every day or having diarrhea for more than 48 hours may lower the pill’s effectiveness in preventing pregnancy.

If you take any of these medications while on the pill, use condoms as a backup method. Diarrhea can interfere with medication absorption, especially if it has been going on for more than a couple of days. If you have diarrhea for more than 24 hours, keep taking your pill as usual and use another type of contraception, such as condoms, until 7 days after your last dose.

Vomiting or having diarrhea for more than 48 hours (2 days) can also lower the effectiveness of your pill. If you take your pill and vomit or have diarrhea for more than two days, the medication is not fully absorbed by the body. One loose stool after one pill will not affect their failure rate.

Does diarrhea affect emergency contraception?

3. How effective is the morning after pill?. No morning after pill is 100% effective, the quicker you take it, the better it will work.

Vomiting or having diarrhoea within a few hours of taking either pill could affect its ability to prevent pregnancy, as your body may not absorb the entire dose. If this occurs, you are advised to talk to your GP as you may need to take the pill again.

Levonorgestrel effectiveness. Levonorgestrel, can be taken up to 72 hours after unprotected sex. It’s thought to be :

• When taken within 24 hours, it is 95% effective
• When taken within 48 hours, it is 85% effective
• When taken within 72 hours, it is 58% effective

Does medication still work if you have diarrhea after taking it?

Key takeaways: It’s possible that an oral medication may not be completely absorbed if you’re experiencing diarrhea. The longer you have diarrhea, the more likely a medication may not be completely absorbed.

Will a pill still work if you poop after taking it?

Your meds are mainly absorbed through your stomach into the bloodstream.

This is usually in the first few hours after taking them.

The time you go to the toilet does not affect this at all.

The only exception might be if you are very ill and have severe diarrhoea. This would be a reason to talk to your doctor in case the meds are not being properly absorbed.

What things make the pill less effective?

What lowers the birth control pill’s effectiveness?. The main thing that makes the pill not work is not taking it every day. But other things, like vomiting or having diarrhea for more than 48 hours (2 days) may lower how well the pill prevents pregnancy.

These medicines or supplements can also make the pill not work as well:

• The antibiotic Rifampin (other antibiotics don’t make the pill less effective)

What things make birth control less effective?

If you take any of these while you’re on the pill, use condoms as a backup method. Switch to a different method of birth control if you’ll be on them for a long time.

Your nurse or doctor can help you decide if there’s any reason the birth control pill won’t work well for you.

How long do birth control pills take to work?. It depends on when you start taking them and what type of pills you’re using. You can start taking the birth control pill any day of the month. But depending on when you start and the kind of pill you’re using, you may need to use a backup birth control method — like condoms — for up to 7 days.

Does diarrhea affect the contraceptive implant?

These medications reduce the effectiveness of the implant by increasing the rate at which your body disposes of the hormone in the blood. If you are using one of these medicines you will need to consider a different or additional contraceptive method.

The implant is not affected by common antibiotics, or by an attack of diarrhoea or being sick (vomiting).

Most women can have an implant fitted but there are a few exceptions. You should not have a contraceptive implant put in if you think you might be pregnant, or if you don’t want to use a contraceptive method that might affect your periods.

You also should not use the contraceptive implant if:

Is there anything that stops the pill from working?

What if I’m taking other medicines?. Some medicines can stop the pill from working.

• Some antibiotics, such as rifabutin or rifampicin
• medication for HIV
• medication for epilepsy

If you’re taking any of these medicines, you’ll need additional contraception. You may wish to change your form of contraception that isn’t affected by your medication.

Always tell your doctor you’re using the pill if you’re prescribed any medicine.

What can stop the pill from working?

What stops the pill from working?you miss a pill or it is taken more than 24 hours late. you vomit within 3 hours of taking it. you have very severe diarrhoea. you are taking some medications or natural remedies. (Check with your doctor, nurse or pharmacist.)

• Oral hormonal contraception is very effective in preventing an unplanned pregnancy, when used correctly.
• The 2 types of oral contraception available in Australia are the combined pill, known as ‘the pill’, and the progestogen only pill.
• Oral contraception does not provide protection from sexually transmissible infections (STIs). The best way to reduce the risk of STIs is to use barrier protection such as condoms and dams with all new sexual partners.

This page has been produced in consultation with and approved by:

This page has been produced in consultation with and approved by:

What cancels out the birth control pill?

Medications for various conditions, including general anesthesia, anti-nausea, and diabetes, as well as supplements like St. John’s wort, can diminish birth control effectiveness.

Imperfect use of birth control, vomiting, diarrhea, improper storage of pills, and certain medical conditions affecting absorption can also reduce contraceptive reliability, highlighting the importance of consulting healthcare providers for guidance and potential use of backup methods.

Can diarrhea affect the birth control pill?

You should take another pill straight away. As long as you’re not sick again, you’re still protected against pregnancy. Take your next pill at the usual time.

If you continue to be sick or have severe diarrhoea (passing six to eight watery stools in 24 hours), this can mean your protection against pregnancy is affected.

Sickness or severe diarrhoea for more than 24 hours. If you can, you should carry on taking your pills at the normal time, but you may need to use extra contraception, such as condoms.

If you continue to be sick for more than 24 hours or you have severe diarrhoea for more than 24 hours, count each day with sickness or diarrhoea as a day that you’ve missed your pill.

Does the pill work after diarrhea?

Very severe diarrhoea (6 to 8 watery poos in 24 hours) may also mean that the pill does not work properly. Keep taking your pill as normal, but use additional contraception, such as condoms, while you have diarrhoea and for 2 days after recovering.

Speak to a GP or nurse or call NHS 111 for more information, if your sickness or diarrhoea continues.

Who can use the combined pill. If there are no medical reasons why you cannot take the pill, and you do not smoke, you can take the pill until your menopause. However, the pill is not suitable for everyone. To find out whether the pill is right for you, talk to a GP, nurse or pharmacist.