Medications That Decrease Contraception Effectiveness

Antibiotics

Despite long-held beliefs that all antibiotics interfere with the effectiveness of hormonal birth control, the only antibiotic drug that has been proven to do so is Rifadin/Rimactane (rifampin). It's commonly used to treat tuberculosis and meningitis.

Rifampin may decrease the effectiveness of NuvaRing and the patch as well. If you're on birth control pills, the patch, or NuvaRing and your doctor prescribes rifampin, you will need to use a backup method of birth control such as condoms or a diaphragm.

Your doctor may recommend a backup method if you're taking other antibiotics, just to be safe.

Anti-HIV Medications

Drugs that are used to treat human immunodeficiency virus (HIV) infection, such as efavirenz, cobicistat, and rifampin, may interact with birth control.

A class of drugs called protease inhibitors, which includes darunavir, nevirapine, nelfinavir, and ritonavir, may also interact with hormonal contraceptives.

Anticonvulsants

Barbiturate medicines for sleep, controlling anxiety, or treating seizures may interfere with the effectiveness of the birth control pill.

Examples of barbiturates include:

• Felbatol (felbamate)
• Lamictal (lamotrigine)
• Luminal, Solfoton (phenobarbital)
• Mysoline (primidone)

Medications prescribed to control seizures in certain types of epilepsy and treat nerve-related pain, as well as Topamax (topiramate), which is prescribed to prevent migraine headaches, may also affect birth control.

Other medications that may also lower the effectiveness of the pill, NuvaRing, or the patch include:

• Trileptal (oxcarbazepine)
• Tegretol, Carbatrol, Equetro, Epitol (carbamazepine)
• Dilantin, Phenytek (phenytoin)
• Topamax (topiramate)

While most women can take lower-estrogen birth control without compromising effectiveness, the World Health Organization (WHO) recommends that women taking anticonvulsants do not use hormonal contraception that has less than 30 micrograms (mcg) of estrogen.

Some women taking these medications may also consider Depo-Provera (medroxyprogesterone acetate) or an intrauterine device, such as Mirena.

Antidepressants

Some medications prescribed for depression can theoretically alter hormone levels. Antidepressants may lower the number of circulating hormones in the body, which can compromise the pill's effectiveness.

However, the effect varies significantly from one person to the next. A decrease in the number of circulating hormones may amount to a bigger drop in the pill's effectiveness for some people, but not in others.

Antifungal Medications

Anti-fungal medications may also lower the effectiveness of the pill, though the World Health Organization states that women taking hormonal contraception should be able to safely use these medications.

Antifungal medications that have been associated with contraceptive failure are:

• The oral suspension Mycostatin, Nilstat, Nystex (nystatin), which is used to treat yeast infections
• Fulvicin, Grifulvin V, Gris-Peg, Grisactin (griseofulvin), which is used to treat fungus infections of the skin, hair, scalp, and nails, as well as ringworm, jock itch, and athlete's foot

Make sure that your doctor knows if you are taking these medications. They can discuss the potential for decreased effectiveness of your current birth control and help you choose a backup method.

Diabetes Medications

Some of the medications for diabetes, including Actos (pioglitazone) and Avandia (rosiglitazone), may interact with ​birth control pills. Make sure to discuss these types of medications with your healthcare provider to see if they will affect the use of your ​oral contraceptives.

Anxiety Treatments

While the research is ongoing, certain medicines used to treat anxiety, muscle spasms, and sleeping problems, such as Valium, Diastat (diazepam), or Restoril (temazepam) may potentially interfere with successful combination contraceptive use.

Pulmonary Hypertension Treatments

Tracleer (bosentan) is a dual endothelin receptor antagonist used to treat people with certain types of pulmonary arterial hypertension (PAH)—which is high blood pressure in the vessels of the lungs. Tracleer has been shown to decrease hormone concentrations in the bloodstream which can put you at more at risk for getting pregnant.

Birth control pills, shots, patches, and implants should not be used alone because they are not reliable when using Tracleer. You must choose and use two reliable forms of birth control at the same time.

If you have had a tubal sterilization or you have an IUD, these methods can be used alone.

Natural Supplements

In addition to prescription medications, certain supplements have been shown to lower the effectiveness of hormonal contraception.

• Soy isoflavones: Natural substances obtained from the soybean plant which claim to reduce the intensity of menopause-related hot flashes and to help maintain strong bones
• St. John's wort: An herbal or dietary supplement that is promoted for its ability to improve mildly depressed mood

Anti-Nausea Medications

Emend (aprepitant), which is used to prevent or treat nausea and vomiting can also interfere with oral contraceptive effectiveness.

While it's not a medication, excessive vomiting and/or diarrhea can also lower the effectiveness of the pill. If you are experiencing these symptoms or taking Emend, use an additional method of birth control and contact your health care provider for advice.