Home pregnancy tests can tell you, with a high degree of accuracy, if you’re expecting when used appropriately at the right time after a skipped period. Although a rare occurrence, pregnancy tests may give you a false positive result if you’re taking certain medications. The Mayo Clinic indicates that birth control pills aren’t a medication that gives you misleading results.

Home Pregnancy Tests

Home pregnancy tests are an inexpensive, expedient way to determine if you’re pregnant. These tests, which can be used in the privacy of your home, detect the presence of a hormone called human chorionic gonadotropin, or hCG — also known as the “pregnancy hormone.” Your body begins to manufacture this hormone about six days after you conceive.

Unreliable Results

It’s possible that you’ll get a false positive result from your pregnancy test if you use one too soon after a recent pregnancy, the Mayo Clinic notes. False positive results may also be the result of ovarian cysts, menopause or an ectopic pregnancy. Medications that can give you a false positive result are fertility drugs that contain hCG. Similarly, it’s also possible to get a false negative result from your home pregnancy test if you use it too soon, don’t give the test enough time to work or drink too many fluids before you take the test — this may dilute your urine.

Drugs and Pregnancy Tests

Birth control pills won’t skew the results of your home pregnancy test. Nor will nonprescription and prescription drugs, including antibiotics. Nor will the use of illegal drugs and alcohol give you faulty results.

Test Basics

To get the most reliable results from your home pregnancy test, the Mayo Clinic suggests using it a week after you miss your period, when levels of hCG can be detected. Take the test when you get up in the morning and your urine is highly concentrated — before you drink any fluids. Follow the instructions inside the packaging to the letter; if you have questions, contact the test’s manufacturer.

If You’re Pregnant

If you’re taking birth control pills and find out you’re pregnant, this isn’t necessarily cause for alarm, says the Mayo Clinic. Scant evidence exisst to suggest that birth control pills will harm your developing child. Nevertheless, birth control pills contain estrogen, which can increase your risk for miscarriage. Stop taking the pill as soon as you discover you’re pregnant, and contact your treating physician.