The pill and Zantac?

Dear Alice,

I have been on the pill for about five months now, and aside from the extra headache now and then, everything has been fine. However, my concern is drug interaction with the pill. A friend of mine recently got pregnant while on the pill, and the nurse practitioner at her school told her it was because she was on Zantac, a medication for ulcers, and it reduced the effectiveness of the pill. I am also on Zantac, and have been advised to take it when I need it, but I am afraid after hearing what happened to her. So, my stomach is getting worse. The doctors here said there wasn't a problem with the Zantac and the pill, though. Who do I believe?

— Dyspeptic Disaster

Dear Dyspeptic Disaster,

The chance of medication such as Zantac (generic name: ranitidine) resulting in the malfunctioning of an oral contraceptive (OC) is pretty small. It is possible that because it decreases the amount of acid in your stomach, it could affect the amount of medication that is absorbed by your body. However, there currently appears to be no specific medical contraindications to taking oral contraceptives and Zantac or any other ulcer medication simultaneously. That being said, there are other medications that do decrease the effectiveness of birth control pills. It’s also good to note that no oral contraceptive is 100 percent effective — or any birth control method for that matter (save for abstinence). And in your friend's case, it's possible that her pregnancy could have been a result of user error, rather than a failure of the method itself (more on that in a bit).

While Zantac seems to pose little risk of interfering with birth control pills, there are a number of drugs that can reduce the effectiveness of OCs. These include anticonvulsants, some drugs used to treat HIV, and rifampin and rifabutin (both antibiotics). In order to mitigate the potential for decreased effectiveness of your OCs, whenever you’re prescribed a new medication, it’s highly recommended that you let the health care provider know that you’re taking birth control pills (or any other medication). That way, s/he will be able to advise you about how to properly take the medication(s), prescribe you an alternative medication that will not interact with your OCs, or share additional steps you might need to take to prevent pregnancy while using the new medication in conjunction with your OCs.

It’s also possible that your friend was unaware that birth control pills have more than one effectiveness rate. Referred to as perfect use and typical use effectiveness, each one coincides with how a person uses the pills. Perfect use effectiveness is attained when a person uses a birth control method correctly and consistently as indicated. This usually translates to taking the pills every day at the same time. When used in this way, combination and progestin-only oral contraceptives are 99.7 percent effective at preventing pregnancy. However, if your friend missed a pill one day, or had taken one late, it may have reduced the effectiveness of the pill and increased the risk of pregnancy. This reduced effectiveness, down to 91 percent for combo and progestin-only pills, is referred to as typical use effectiveness.

It’s not hard to imagine forgetting to take a pill or missing a reminder to take one at a certain time. The good news is that there are other birth control methods that do not require daily maintenance. If you’d like to learn more about other birth control options, take a look at the Contraception category in the Go Ask Alice! Sexual and Reproductive Health archives. Lastly, if you still feel worried about the pill's effectiveness with your ulcer medication, try using a back-up method of contraception, like condoms, when you have ulcer flare-ups and take Zantac.

Last updated Jun 19, 2015
Originally published May 01, 1994

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