Diarrhea and Birth Control Pills

Diarrhea might interfere with your birth control pills

Diarrhea can make birth control pills less effective. If you use oral birth control, even one episode of diarrhea can slightly increase your risk of becoming pregnant.

This article explains how diarrhea can negatively affect birth control. It discusses when you should use backup contraception. It also talks about other birth control options.

Woman with birth control pills
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How Diarrhea Interferes With the Pill

Oral contraceptives work by changing your hormone levels. This stops you from ovulating (releasing eggs from your ovaries). This, in turn, prevents you from getting pregnant. The pill is usually over 99% effective when taken as directed.

The active ingredients in the pill work over the course of your menstrual cycle. Their effectiveness depends on taking them on a regular basis. When you miss a dose or two, you may ovulate and become pregnant.

Diarrhea affects how well your body absorbs foods, liquids, and medications. Instead of being taken up into the bloodstream, they are lost in the stool.

If the active ingredients in your birth control pills aren't absorbed through your intestines, they won't do the job they were designed to do.

Acute Diarrhea and the Pill

Diarrhea can happen suddenly due to an infection, food poisoning, a food allergy, or food sensitivity, like lactose intolerance.

The pill may no longer protect against pregnancy if you have severe diarrhea for more than 24 hours. Severe diarrhea means you pass six to eight watery stools in a 24-hour period. The pill also may not work if your diarrhea is not severe but lasts over 48 hours.

If you rely on oral contraception for birth control, call your doctor. The doctor's advice will be based on:

  • How long you've had diarrhea
  • How frequent it is
  • If you've had sex in the last five days
  • What day of your cycle you are on

Your doctor will probably tell you to finish your current pill pack to keep your menstrual cycle on schedule. You may also need to use a different method of birth control until you finish a week of hormone pills or have your period.

CDC Recommendations
 If...  Then...
Diarrhea occurs within 24 hours of taking oral birth control or continues for 24 to 48 hours after taking a pill... You do not need to take an additional dose. Continue to take your pill every day, as long as it doesn’t make your stomach feel worse. You do not need backup birth control. Emergency contraception should not be needed, but call your doctor to make sure.
Diarrhea lasts more than 48 hours... Use backup birth control, such as condoms, or avoid sexual intercourse until pills have been taken for seven diarrhea-free days.
Diarrhea lasts more than 48 hours and occurs during the last week of hormonal pills...  Finish the hormonal pills, skip the hormone-free period, and immediately start a new pack. Use backup birth control until pills have been taken for seven days after the diarrhea stops. 
Diarrhea lasts more than 48 hours during the first week of a new pill pack, and you had unprotected sex in the past five days... Consider emergency birth control.
Source: Centers for Disease Control and Prevention. CDC Contraceptive Guidance for Health Care Providers. Updated February 1, 2017.

Chronic Diarrhea and the Pill

Illnesses that cause chronic, repeated bouts of diarrhea can make oral birth control a problem. The most common conditions that cause chronic diarrhea include:

These conditions may begin before you started taking birth control or after you have been taking the pill for a while. Chronic diarrhea is also common after gastric bypass surgery and some other procedures involving the intestines.

In addition, chronic diarrhea can come and go. It can recur for months, resolve for a period of time, then return. If you develop chronic diarrhea after reliably using birth control pills for a while, talk to your doctor.

It is commonly recommended that women who live with chronic diarrhea use birth control methods other than the pill.

Alternative Methods of Birth Control

The pill is just one form of birth control. Other types of contraception that aren't taken orally and aren't affected by diarrhea include:

The vaginal ring, for example, provides the same hormones as the pill. The difference is that the hormones are absorbed through the vaginal wall.

If you need to use backup birth control while on the pill, choose a barrier method such as a condom or diaphragm.

Summary

If you take oral contraceptives, be aware that having diarrhea can change their effectiveness.

Diarrhea can impact the pill if it:

  • Occurs six to eight times in a 24-hour period
  • Lasts for more than 48 hours

Women with chronic conditions that cause frequent diarrhea may want to consider a different birth control method, such as a vaginal ring or IUD.

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4 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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