Most medications, including common prescription medications such as antibiotics or birth control pills will not interfere with the results of a pregnancy test. However, there are a select few medications, typically fertility medications, that can interfere with pregnancy tests.

Before going any further, it is important to know the process that makes home pregnancy tests work. Home pregnancy tests measure a hormone known as, human chorionic gonadotropin, also known as hCG for short. For a pregnancy test to show a positive result, your body must be producing a level of hCG that the test can detect. Not all pregnancy tests are the same, however. Some tests are more sensitive than others and will show a positive result earlier than tests that are less sensitive. The box that the test came in should indicate somewhere what its sensitivity is. Sensitivity is measured in IU/L, which stands for milliInternational Units per Liter. A very sensitive test may have a sensitivity of 20 IU/L, whereas a test that is not as sensitive might have a sensitivity of 50 IU/L.

Because of the sensitivity issue, the timing of when you take a home pregnancy test can determine its accuracy. A very sensitive test may be able to produce a positive result as little as 7 days after ovulation. Implantation must occur before hCG is produced, and implantation will generally take place 6-12 days after ovulation. Thus, it makes sense to try to wait at least 12 days after ovulation to test for a reliable result. If you cannot wait that long and have other symptoms of pregnancy, you might use a test that is higher in sensitivity, but keep in mind that even if the result is negative you may still be pregnant, but just not implanted.

The only medications that should interfere with pregnancy tests, then, would be medications that contain hCG. In addition, you would have to be using a particularly sensitive pregnancy test, as the levels of hCG in your system from such medications is typically not high enough to be recorded on a home pregnancy test. When this does happen, it is referred to as having a “false positive” result. Some of the drugs that could give a false positive might include Profasi, Pregnyl, and Novarel, but only if the test is taken within one to two weeks of getting the shot.

Posted in Pregnancy

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