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Can I Still Get Pregnant if I'm on the Pill?

Medically Reviewed by Traci C. Johnson, MD on October 14, 2020

It’s happened to a lot of people -- maybe even you. You got busy and forgot to take your birth control pill. The moment you realize it can be scary, but it doesn’t necessarily mean you’ll get pregnant.

Birth control pills aren’t 100% effective at preventing pregnancy, but they come close when taken exactly as directed.

Because no method of birth control is guaranteed to prevent pregnancy, and because it’s so easy to make mistakes, it’s important to understand what birth control pills do and how you can make them more likely to work.

How Effective Is the Pill?

Birth control pills are considered effective, but not foolproof. They’re about 99% effective when you take them correctly.

But that’s if you take them perfectly, meaning at the same time each and every day. If you don't, your odds of becoming pregnant go up to 9%.

Types of Pills

There are different types of birth control pills, including combined pills and mini-pills. No matter which kind you use, it’s crucial to take them exactly as prescribed, even on the days you don’t have sex.

Combined pills contain two hormones, estrogen and progestin. A pack of combined pills usually has 21 to 24 days of hormones and 4 to 7 days of reminder pills. You should get your period while taking the reminder pills.

You might take one pack of combined pills every month, or you can take the hormone pills continuously to delay or stop your periods. It’s generally considered safe to skip or eliminate your periods, but you should discuss this option with your doctor and then follow their instructions on when to take the pill.

Mini-pill packs contain only one hormone, progestin. If you’re taking mini-pills, it’s very important to take all 28 pills at the exact same time every day. If you’re late taking a pill by just 3 hours, you have to use a backup method of birth control, such as a condom.

Starting the Pill

The pill doesn’t start working right away. You need to take it for at least a few days before it becomes effective. That’s why it’s important to use a backup contraceptive, like condoms, when you first start taking it. Talk to your doctor about how long you need to use a backup method. Some recommend you use one during your entire first pack.

Talk to your doctor if you just had a baby or are breastfeeding and want to take the birth control pill. You may have to wait for a certain period of time before it’s safe to start on the pill.

Remember, the pill doesn’t protect against HIV or other sexually transmitted diseases, so you need to continue to use condoms every time you have sex, especially with new partners, to stay safe.

Missed Pills

You should take all your pills as directed, no matter what. Skipping a pill for any reason can increase your chances of becoming pregnant. If you’re tempted to skip a pill because they are causing side effects, talk to your doctor, but continue taking them. Many women who have side effects when they first start taking the pill feel better after 3 months.

If you accidentally miss one pill, there’s probably no need to worry. Just take it as soon as you remember and continue taking your next pill at the regular time. If it’s a mini-pill and it’s been more than 3 hours, use a backup method of contraception.

If you’re taking combined pills and miss two or more hormone pills, you should call your doctor. What you should do next will depend on what kind of pill you’re on, so they can advise you. No matter what, you should use a backup method of birth control, like a condom, since your chances of getting pregnant are much higher after you miss two or more pills.

Alcohol and the Pill

Whether or not it’s a great idea, alcohol and sex often end up together. Drinking alcohol won’t change how well your birth control pills work. But, because effective use of the pill relies on memory, you’ll need to think ahead when drinking is in your future.

Alcohol addles your mind and alters your behavior. It can make you more careless -- and derail your intentions to use birth control pills responsibly. A study of binge drinking in young women found risky drinking nearly doubled the odds of contraception not working well.

Drinking too much can also make you throw up. If you throw up after taking the pill less than 2 hours prior, it can come back up, and then it's as if you never took it at all.

Oral contraceptives can also affect how your body processes alcohol. Like some other drugs, birth control pills slow down the rate at which your body absorbs it, making it linger longer. And the longer you're under the influence, the more time there is to forget to take your pill, too.

If you plan to imbibe, the way to stay on track with your birth control is to plan ahead.

  • Use reminder apps. You can find a wide variety of these with a web search. Many can track your period and even your pill inventory.
  • Take your pill early in the day instead of the evening, when impromptu events might come up.
  • Carry backup protection such as a condom and spermicide. Ask your partner to support your efforts and do the same. You should always use condoms to protect against sexually transmitted infections (STIs) unless you're in a long-term, faithful relationship.

 

Other Reasons the Pill Can Fail

You don’t store it right. Birth control pills should be stored at room temperature, away from moisture and heat, so don’t keep them in your bathroom. Make sure to keep them in their original packaging to protect them.

Other medications. Some medicines can make your birth control pill less effective. Most antibiotics are safe to take while you’re on birth control pills, but one -- rifampin (Rifadin IV) -- can stop the pill from working. Tell your doctor you’re on birth control if he prescribes you rifampin.

Other medicines like mood stabilizers, epilepsy medicines, and HIV drugs can also make the pill less effective. Make sure to discuss these with your doctor.

Certain herbs. The supplement St. John’s wort is popular for issues like depression or insomnia, but it can reduce the amount of hormones in the pill. Talk to your doctor if you’re taking this herb and consider using a backup method of birth control while you’re on it.

WebMD Medical Reference

Sources

SOURCES:

CDC: “Effectiveness of Family Planning Methods,” “Contraceptive Effectiveness.”

U.S. Department of Health and Human Services: “Birth Control Pill Fact Sheet.”

HealthyWomen.org: “How to Effectively Use Your Birth Control Pills.”

Association of Reproductive Health Professionals: “Using Birth Control Pills Regularly for Successful Contraception.”

MedlinePlus: “Estrogen and Progestin (Oral Contraceptives).”

Bedsider.org: “Which medications can mess with birth control?”

Alcohol Addiction Centers: "Can Alcohol Lower the Effectiveness of Birth Control?"

“Spot On Period Tracker,” “What are the Benefits of IUDs?” “Birth Control Implant.”

Princeton University: “The Emergency Contraception Website.”

Psychology & Health: “Risk Drinking and Contraception Effectiveness Among College Women.”

Addiction: "Alcohol consumption and the intention to engage in unprotected sex: systematic review and meta‐analysis of experimental studies."

National Health Service (U.K.): "What if I'm on the pill and I'm sick or have diarrhoea?"

Alcohol, Clinical and Experimental Research: “Ethanol Metabolism in Women Taking Oral Contraceptives.”

Her Campus at the University of Florida: “5 Birth Control Reminder Apps To Download.”

Office on Women’s Health: “Birth Control Methods.”

University of Texas Southwestern Medical Center: "Would an IUD or birth control implant work for me?"

The Royal Women’s Hospital: “Contraception and Substance Use.”

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