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9 medications that interfere with birth control

Certain antibiotics, antifungals, and even some supplements can make contraception less effective

Birth control failure is much more serious than a Tylenol that hasn’t quite cured your headache. If your birth control doesn’t work, then you risk an unwanted pregnancy. So, it’s important to be aware of any medications that may interfere with your contraception’s effectiveness.    

Before you take any new medication consult with your healthcare provider or pharmacist to see if the medication could interfere with your birth control pills.

9 medications that interfere with birth control

The following drugs and supplements may interfere with the effectiveness of birth control pills.

1. Antibiotics 

Even though many people think that antibiotics may interfere with birth control pills, most types of antibiotics do not. Research shows that the only antibiotic known to interfere with birth control pill effectiveness is rifampin

“Antibiotics, especially rifampin, are thought to affect the absorption of birth control pills because they alter the environment of the stomach,” says Kristi C. Torres, Pharm.D., a member of SingleCare’s Medical Review Board.

But since you could get pregnant if the antibiotic does interfere, you are safest using a backup form of contraception (such as a barrier method) or emergency contraception (if needed) when taking antibiotics and birth control. 

2. Anti-HIV drugs

Research shows that some retrovirals that are used to treat HIV can make your birth control less effective. Sustiva (efavirenz), in particular, was shown to compromise effectiveness. Check with your healthcare provider before taking an anti-HIV treatment alongside birth control pills.

3. Antifungal medications 

Certain oral or intravenous antifungal medications could cause your birth control pills to be less effective. Gris-peg (griseofulvin)—used to treat jock itch, ringworm, or athlete’s foot—particularly can interact with contraception. Antifungal ointments, creams, and powders that you apply to the skin do not interfere with oral contraception.

“Antifungals such as fluconazole and itraconazole inhibit the enzyme that is partially responsible for the metabolism of birth control pills,” Dr. Torres says. “This could potentially lead to increased plasma concentrations of estrogen. This could result in nausea and breast tenderness. Short courses of antifungals may not present a clinically significant problem, but longer courses may present more of a concern.”

If you’re picking up a prescription for an ailment like a yeast infection, or the infections mentioned above, check with the pharmacists first to make sure it won’t affect the birth control you use.

4. Anticonvulsants 

Medications that treat seizures, or ones that are used by people who have epilepsy, have been known to interfere with birth control pills. “Topamax, or generic topiramate, commonly used for both migraine prophylaxis and seizures, may also render your birth control less effective,”  Dr. Torres says.

5. General anesthesia 

If you are having any procedure done that requires anesthesia it is important to let the surgeon know that you take birth control pills, since it may interfere with the effectiveness. 

“Sugammadex is used to reverse neuromuscular blockages involved with surgical procedures,” says Taylor Graber, MD, a resident anesthesiologist at University of California San Diego and owner of ASAP IVs. “One of the side effects of this medication is that it binds to and temporarily inhibits birth control medications.”

6. Anti-nausea medications

Research shows that Emend (aprepitant), a medication that blocks the chemicals that cause nausea, can interfere with birth control effectiveness. It’s also important to note: If you vomit after taking your regular dose of birth control, it may not have been fully absorbed. Treat it like a missed dose, and use a backup contraceptive until you’re fully protected again.

7. Pulmonary hypertension medication 

Tracleer (bosentan) is a medication used to treat people who have high blood pressure of the lung vessels. This medication may interfere with birth control effectiveness by decreasing the hormone levels in the blood. It also carries the risk of severe birth defects, so it’s recommended that any woman taking it use two methods of birth control.

8. Diabetes medications 

Research has shown that Actos (pioglitazone) and Avandia (rosiglitazone maleate), medications that treat diabetes, may decrease ​birth control pill effectiveness. Talk to your endocrinologist or OB-GYN to find out if there are alternative treatment methods.

9. Herbal supplements and vitamins

St. John’s wort is a supplement that people take to help with symptoms of depression, insomnia, or anxiety. Soy isoflavones is from a soybean plant and may reduce menopause-related hot flashes or help maintain strong bones. Research has shown that supplements like these may reduce the effectiveness of birth control pills.

“There is some thought that St. John’s Wort, typically used to help with symptoms of depression, contains ingredients which may speed up the breakdown of estrogen, rendering birth control less effective,” Dr. Torres says. “Vitamin C, often taken to boost immune function, can interact with birth control as well. Estrogen can cause increases in vitamin C levels, which could potentially be problematic.”

RELATED: 3 types of medications that could have a vitamin interaction

How to prevent birth control ineffectiveness

Always talk with your doctor about birth control interactions before taking new medications, including vitamins or over-the-counter medications. Ask if the medication or supplement will interfere with your birth control effectiveness. Even if more research is needed, it’s generally better to err on the side of caution. You can use backup forms of birth control in addition to oral contraceptives when taking medications that interfere with the effectiveness. 

If you forget to use a backup method, you can take over-the-counter emergency contraception for up to five days after intercourse. For long term medications, such as retrovirals, diabetes medications, or anticonvulsants, it is best to talk with your provider about other contraception methods, such as long-acting reversible contraception or injectable progesterone.