While hormonal birth control has a whopping 99% success rate at preventing pregnancy, that number only applies to birth control when it’s used perfectly. If you’re human and slip up every once in a while when it comes to taking your pill, that effectiveness goes down to 91%. However, a couple other factors might be reducing the effectiveness of your birth control.
1. Other Medications. As everyday as birth control may seem, it is a medication and subject to interaction with other medications. Here’s a quick list of medications that might be interfering with your birth control (you can read more in depth here).
- Antibiotics for tuberculosis or meningitis (Rifampin or Rifabutin)
- Anticonvulsants or mood stabilizers (Felbatol, Lamictal, Luminal, Solfoton, Mysoline, Trileptal, Tegretol, Carbatrol, Equetro, Epitol, Dilantin, Phenytek, and Topomax)
- HIV medication (Nelfinavir, Nevirapine, Tipranavir, Lopinavir, Fosamprenavir, and Darunavir)
- Antifungal medications (Nilstat, Nystex, Mycostatin, Grisactin, Grifulvin V, Gris-Peg, and Fulvicin)
- Diabetes medication (Actos, Avandia, and Troglitazone)
- Anti-anxiety medication (Valium, Restoril, and Diastat)
- Pulmonary Arterial Hypertension Medication (Tracleer)
- Anti-nausea medication (Emend)
- Antidepressants (In general, these are safe to take with birth control, but some women will feel an interaction. Talk to your doctor if you’re on antidepressants and worried about combining them with birth control.)
2. Natural Supplements. Some natural supplements have also been known to interact with birth control.
- St. John’s Wort is an herbal supplement that can help with depression, insomnia, and anxiety. However, it decreases the pill’s hormone concentration in the blood by 15%, reducing its effectiveness.
- Soy Isoflavones are the active ingredients in soy and, according to some, can help treat menopausal hot flashes and build strong bones. They’ve also been shown to negatively interact with hormonal birth control.
- Vitamins A, C, and potassium might interact with the effectiveness of birth control in really high doses, but the research is inconclusive. Don’t worry about your daily vitamin dose getting you pregnant, but if you’re downing six packs of Emergen-C a day, maybe give it a rest (for your birth control and your body’s sake!).
3. Higher Body Weight or BMI. A high body weight can affect your metabolism, causing you to absorb drugs faster than intended. Since your body metabolizes the drug so fast, there’s not enough in your bloodstream to render the drug effective. If you have a BMI over 27, the pill, patch, or Nexplanon may not your best birth control options. Talk to your doctor to figure out the best contraception for you.
4. Storing Your Birth Control at Inconsistent Temperatures. Basically all medication should be stored in a consistently dry, room temperature location. This is especially true of birth control, which is particularly sensitive to its environment. While this might seem like an easy task, it takes more thought than you might guess. For example, one bad place to store birth control? Your medicine cabinet, which experiences frequent temperature and humidity changes from the shower and bath. Another bad place? Your car, which can reach unbearable temperatures in heat (especially the glove compartment). It might not be a good idea to store your birth control in your purse, either, if you’ll be going through extreme temperature changes on long commutes. Just give a little thought to where you store your heat-sensitive pills and vaginal rings, to ensure maximum protection (remember, rings become less effective after being exposed to 86 degree or higher heat).
5. Taking Your Pill Inconsistently. The pill always comes with the same piece of advice: take it at the same time every day. But how necessary is this, really? Luckily for combination-pill users, the answer is not very necessary. That’s right, if you’re on a combination estrogen-progestin pill, you only have to take it once a day to ensure pregnancy protection. You’ll even be protected if you miss a pill, so long as you’re not on the first seven days of a new pack. However, if you’re on progestin-only pills, you have to take them within the same three-hour window every day. In any case, it’s good to take the pill at the same time every day so you build the habit of taking it. If you have trouble remembering, use your phone. Set alarms and reminders so you’ll never miss a pill.
6. Vomiting and Diarrhea. Vomiting and diarrhea will negatively impact the effect of oral contraceptives by keeping the body from absorbing them properly. Just remember that if you get sick, your birth control won’t be as effective for the duration of your vomiting or diarrhea spell. Make sure you double up on contraceptives when you’re feeling well enough for sexual activity.
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