In the old days, if something happened -- the condom broke or something worse -- and you needed to prevent pregnancy, there was basically one option: emergency contraception. You took two different pills, 12 hours apart, to try to backpedal. That changed on July 14, when the FDA approved the first ever one-dose, over-the-counter version of the well-known EC: Plan B One-Step. Here's how One-Step is different from its prior form, Plan B: Original Flavor, and other past and present types of EC.

How It Works

In addition to Plan B 1.0 and 2.0, other EC pills include Preven, which is no longer sold in the U.S., and Next Choice, a generic version of Plan B approved by the FDA last month. These pills prevent pregnancy in three ways: reducing the probability of an egg being released from the ovaries; thickening the cervical mucus to lessen the chance of sperm reaching the egg and changing the lining of the uterus to prevent a fertilized egg from attaching to the womb.

Plan B One-Step differs from its two-step predecessor in that it's one pill with a higher dose of levonorgestrel, a synthetic progestogen. While pills like Preven are said to decrease the likelihood of pregnancy by 75 percent, Plan B One-Step manufacturers say their pill lessens the chance of conceiving by about 87 percent if taken within 72 hours of unprotected sex.

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Reports say that progestin-only pills like Plan B One-Step, original Plan B and the generic form are more effective and also have fewer side effects than pills like Preven, which contain both progestin and estrogen. According to the manufacturer's Web site, Plan B One-Step may cause nausea, abdominal pain, fatigue, headache, dizziness and breast tenderness, side effects common in other forms of EC. It may also cause a heavier or lighter next period, or a period that is early or late.

With the new pill and the old, there are few health risks, says Dr. Melissa Dugan-Kim, OB/GYN at the Northwestern Specialists for Women in Chicago.

"Emergency Contraception with Plan B is safe and appears to be effective at preventing unintended pregnancy," she said. "While I in no way feel that women should rely on this form of birth control, I do think there is a need for its easy availability, especially in cases of a failure of another form of birth control or in the case of sexual assault."

Easy to Swallow

Perhaps the biggest difference between Plan B One-Step and the two-dose pills is that it makes things more convenient. With two-dose EC, many women wait to take the first pill so they don't have to wake in the middle of the night to take the second, or forget about the next dose altogether. Since the effectiveness of the pill decreases by the hour, any delay is risky.

Plan B One-Step is also easier to get. If you're 17 or older, you can get it at your pharmacy counter without a prescription, regardless of where you live. Those under 17 must go to their doctor or a clinic to get it.

Lemondrop readers say they've taken the original Plan B for various reasons.

Staci H. took the old Plan B at 21 after the condom broke during sex with her boyfriend. After researching potential risks, she bought it from a drugstore.

"I was terrified that the pill would not work," she said. "I read and understood that the pill would not terminate an existing pregnancy but only prevent an egg from attaching to the uterus. At that point, it had only been a couple of hours since the condom had broken, and I was confident that I was not pregnant. I only wanted to prevent myself from becoming pregnant [should the sperm fertilize an egg]."

Staci had no side effects and did not get pregnant. "I don't know what I would have done if things turned out differently," she added.

Meg S., 26, of Illinois, took emergency contraception twice -- the first time after unprotected sex, the second after going several rounds with protection.

"I was made aware of the risks in college, although I don't think I'd pass a quiz on the side effects now," said Meg, who was with a committed partner both times. "I didn't take any follow-up pregnancy tests, as I always had my period shortly after I took the pill."

Tell us: Have you taken EC? How'd it make you feel? Not just physically, but emotionally too.