What is hormonal birth control?
Hormonal birth control methods include:
- The patch (Evra®)
- Injectable birth control (Depo-Provera®)
- Hormonal intra-uterine system (IUS) such as Mirena®, Jadess® and Kyleena™
- Vaginal ring (NuvaRing™)
- Oral contraceptive pills (the Pill)
Hormonal birth control methods prevent pregnancy by using 1 or 2 hormones similar to the estrogen and progestin produced by a woman’s body.
How do hormonal birth control methods work?
A woman becomes pregnant when her egg is fertilized by a man's sperm. The fertilized egg attaches to the lining of the uterus where it grows and develops into a fetus.
A woman’s hormones control the release of the egg and prepare her body to support the growth of the fetus.
Hormonal birth control methods help prevent pregnancy by doing one or more of the following:
- Preventing ovulation (i.e., the ovary does not release an egg)
- Thickening the cervical mucous, which makes it difficult for the sperm to enter the uterus
- Thinning the lining of the uterus, in case a woman did ovulate, (i.e. missed taking pills towards the end of the pack), making it difficult for an egg to be implanted
Can other medications affect my birth control?
Yes. Certain medications may make your hormonal birth control not work properly or not work at all.
Medications that may decrease the effectiveness of your birth control include, but are not limited to:
- Antibiotics such as rifampin
- Anticonvulsants or anti-seizure medications such as carbamazepine (Tegretol®), phenytoin (Dilantin®), oxcarbazepine (Trileptal®), primidone or topiramate (Topamax®)
- Antifungal medications such as griseofulvin;
- Anti-retrovirals such as ritonavir
- Herbal medications such as St. John’s wort
It is important to inform your health care provider and pharmacist about any medications, dietary supplements, or recreational drugs that you are taking. They can discuss medication options with you that will not affect your birth control.
How does hormonal birth control affect my other medications?
Hormonal birth control can decrease the effectiveness of some medications such as anti-seizure medications. In some cases, you may need a different dose of your medication or may be switched to a different medication when you are taking hormonal birth control.
Ask your health care provider about how your hormonal birth control may affect your other medications and about birth control methods that work best with the medications you are taking.
How can I prevent pregnancy when using hormonal birth control with other medications?
If you are taking medications that affect your birth control, talk to your health care provider about your birth control options. You may need to use a backup method, such as a barrier method in addition to your hormonal birth control, to prevent pregnancy.
Barrier methods of birth control include:
- Cervical caps
These methods are not affected by medications. Condoms are the only birth control method that protects you against sexually transmitted infections (STIs).
Some anti-seizure medications and other drugs such as isotretinoin (Accutane® for acne) significantly increase the risk of birth defects. It is important to use effective birth control to prevent pregnancy and to plan any pregnancy carefully with your health care provider’s advice.
Speak to your health care provider about how long you should use an additional method of birth control, even after you stop taking a medication that affects your birth control.
For More Information
For more information on birth control options and how to prevent pregnancy while taking medications or herbal supplements, speak with your health care provider, pharmacist, or public health nurse.
For information about sexually transmitted infections, see HealthLinkBC File #08o Preventing Sexually Transmitted Infections (STIs).