If you’re sick and your doc prescribes antibiotics, make sure to check the package insert and ask your doctor or pharmacist for information before getting hot ’n’ heavy. In many cases, antibiotics can reduce the effectiveness of birth control pills by reducing the amount of certain hormones (found in birth control pills) in the bloodstream. If the level of hormones gets too low, the drug won’t work to prevent pregnancy. Rifampin, one type of antibiotic, is especially likely to reduce the Pill’s effectiveness. (So grab that box of condoms on your way out of the pharmacy.)
St. John’s Wort
Think “herbal” means “can’t do anything wrong to your body”? Think again. St. John’s wort is a top-selling botanical product that’s been used for centuries in medicine. And since you don’t go to the doctor to get it (it’s just sold OTC in pharmacies and health food stores), there’s no one to warn you about the possible drug interactions. Basically, St. John’s wort increases the breakdown of estrogen in the body, one major hormone of many oral contraceptives. The bottom line: You’ll need an extra form of birth control if you’re taking the Pill and St. John’s wort.
Your doctor wasn’t kidding when she said to take the Pill at the same time every day. Taking it at different times (or missing one completely) makes it less effective -- this is especially true for progestin-only pills. Can’t commit to a timed schedule? You might want to look into other birth control options or think about supplementing the Pill with regular condom usage (yep, every time).
This one is twofold. Oil-based lubricants can weaken latex condoms and cause them to tear (yikes!), while silicone-based lubricants can weaken forms of silicone-based birth control, like diaphragms or cervical caps. Try a water-based lubricant, like K-Y Brand Jelly, to avoid problems.
Nestpert: Debby Herbenick, PhD, research scientist at Indiana University and author of Because It Feels Good: A Woman's Guide to Sexual Pleasure and Satisfaction