Before you pour yourself a glass of grapefruit juice or slice open a grapefruit at breakfast, consider how this tart fruit might affect the medicines you take. Both grapefruits and their juice are known to interact with dozens of medicines, including birth control pills.
If you’re on the pill, should you consider switching to a different breakfast fruit?
Birth control pills contain man-made forms of the female hormones estrogen and progestin. Normally, a rise in estrogen levels in the middle of a woman’s menstrual cycle causes her ovaries to release a mature egg. This process is called ovulation. The egg is then ready to be fertilized by a man’s sperm. Once the egg is fertilized, it attaches to the wall of the mother’s uterus, where it can grow into a baby.
The hormones in birth control pills interrupt a woman’s natural cycle and prevent the egg from being released. These hormones also thicken cervical mucus, making it harder for sperm to swim up through the cervix to reach the egg. Birth control also changes the uterine lining to make it harder for an egg that has been fertilized to attach and grow.
When used correctly, birth control pills are 91 to 99 percent effective. That means for every 100 women who take the pill, one to nine of them could get pregnant during any given year. Women who do get pregnant while on the pill often conceive because they skipped pills or didn’t take them correctly.
Chemicals in grapefruit interfere with an enzyme in the intestines called CYP3A4, which affects how your body breaks down and absorbs certain medicines. When you eat grapefruit or drink grapefruit juice, you can either absorb too much or not enough of these medicines. This means you might develop more side effects from the drug, or the drug may not work as well as it should.
In the case of birth control, grapefruit and grapefruit juice decrease the breakdown of estrogen in the body. This increases the amount of the hormone in your system. Although the increase in estrogen shouldn’t make the pill less effective, it could potentially increase the risk of side effects like blood clots and breast cancer. It’s worth noting that this hasn’t been proven.
Grapefruit and its juice can interact with more than 80 different medicines, including:
- fexofenadine (Allegra), which is used to treat allergies
- buspirone (Buspar) and sertraline (Zoloft), which are used to treat depression and anxiety
- sildenafil (Viagra), which is used to treat erectile dysfunction
- nifedipine (Procardia), nimodipine (Nimotop), and nisoldipine (Sular), which are used to treat high blood pressure
- atorvastatin (Lipitor), lovastatin (Mevacor), and simvastatin (Zocor), which are used to treat high cholesterol
- saquinavir (Invirase), which is used to treat HIV
- erythromycin, primaquine, and quinine, which are used to treat infections
- amiodarone (Cordarone), which is used to treat an irregular heartbeat
- cyclosporine and tacrolimus (Prograf), which are used to prevent organ transplant rejection
How these drugs interact with grapefruit depends on the medicine. It also depends on the person taking the medicine because your genes can influence how much grapefruit affects drug metabolism.
Grapefruit isn’t the only substance that can interact with your birth control. Other medicines can also change the effectiveness of your pills, including:
- medicines that are used to treat diarrhea
- griseofulvin, which is used to treat skin infections such as jock itch and athlete’s foot
- medicines that are used to treat seizures
- rifampin, which is used to treat infections such as tuberculosis
- St. John’s wort, which is an herbal supplement that’s used to treat depression
Check with your doctor if you take any of these medicines and birth control.
If you want to make grapefruit and grapefruit juice part of your diet, ask your doctor how they’ll affect your birth control. You should be able to eat grapefruit as long as it’s at a different time than when you take your birth control pill. For example, it should be OK to have grapefruit for breakfast if you take your pill in the evening.
It’s a good idea to let your doctor know about all the medicines you take. Ask how they could interact with each other and with the foods you eat.
To prevent a pregnancy, take your birth control pill exactly the way your doctor prescribed. Taking it at the same time every day, such as when you brush your teeth, will not only help you remember your pill, but it will also make your birth control more effective.
If you miss a day, take the next pill as soon as possible. You might need to use a backup method of birth control, such as a condom or a diaphragm, for a week after you’ve missed a pill.