Reuters

One million packets of birth control pills, including Lo/Ovral-28, have been recalled because they may not contain enough contraceptive to prevent pregnancy.

If you’ve been taking the birth control pills that were recalled Wednesday, there are some simple steps you can take to protect yourself against an unwanted pregnancy.

Pfizer announced that it had voluntarily recalled14 lots of Lo/Ovral-28 tablets, which contain the hormones norgestrel and ethinyl estradiol and 14 lots of generic versions of the pill—a total of 1 million pill packs—because of a packaging error.

The problem, according to Pfizer, was that some of the packs contained an incorrect number of inactive or active ingredient tablets and the tablets might be in the wrong order.

The pills come in blister packs of 28. The active ingredient pills, taken for the first three weeks, are white-ish in color, while the inactive pills, taken for the last week to help women keep track of when they should begin their next pack of pills, are pinkish.

On YouTube, Pfizer’s chief medical officer, Dr. Freda Lewis-Hall, said perhaps as few as 30 packets were affected, but the company pulled entire lots to be on the safe side.

“We understand that this news can be very concerning and confusing for any woman who takes birth control pills to protect against unintended pregnancies,” Lewis-Hall said in the video.

If you’ve been taking one of the recalled pills, check the lot number on the package to see if it’s one that’s been recalled. Both Pfizer and the Food and Drug Administration have posted the lot numbers.

If you discover you have been taking pills from an affected lot, “assume that you do not have any birth control protection,” advises Dr. Kristen Eckler, an obstetrician and gynecologist at Massachusetts General Hospital in Boston and instructor at Harvard Medical School.

If you’ve had sexual intercourse in the last few days, Eckler says, she would “strongly encourage” you use emergency contraception as soon as possible if you want to avoid an unintended pregnancy. Plan B, available without a prescription to those 17 and older, is effective up to three days after unprotected sex, while prescription ella works up to five days afterward.

When you return your recalled pills to your pharmacy, you could obtain a new pack and start taking pills right away, Eckler says. You might have some minor breakthrough bleeding, breast tenderness or digestive tract upset, she says, but those should pass in a few days.

Because you can’t be sure where you are hormonally, Eckler says, you “absolutely have to use a barrier method (a male or female condom) during that first new pill pack.”

If birth control pills have been an effective method of birth control for you in the past, don't give up on them, she says.