Seventeen-year-old Tara had unprotected sex with her boyfriend "without really thinking," she says.

Plan B: a brand of
emergency contraception

Let's face it. We sometimes do risky things in the heat of the moment. Or, even if we're careful, our birth control can fail. Even worse, some girls are sexually assaulted and need to prevent pregnancy after the fact.

Emergency contraception (EC) is a type of birth control that gives girls another chance to avoid pregnancy.

Emergency contraception comes in the form of pills (commonly known as the "morning-after pill," even though you can take it up to five days after). The pills are sold under the brand name Plan B.

EC pills are basically high dosages of the birth control pill. They do not cause an abortion. They work by preventing ovulation (an egg being released from the ovary), fertilization (the egg and the sperm coming together), or by preventing the fertilized egg from attaching to the uterus, and so they prevent pregnancy.

EC will not work if you are already pregnant, and it does not protect against sexually transmitted diseases (STDs).

Although studies show that emergency contraception can be taken up to five days after intercourse, the sooner you use it, the better your chances of not getting pregnant. That means if you take the pills within one day of unprotected intercourse, there will be a better chance of avoiding pregnancy than if you wait until after the fourth day.

Some girls experience side effects when they take EC pills. The most common are abdominal pain, fatigue, irregular bleeding, headaches, and breast tenderness. Like most medications, though, reactions vary from person to person. Tara says she "ended up vomiting for a good two hours," while Amy, 18, of Boulder, CO, experienced no side effects at all.

"The process of getting EC was pretty easy, actually," Tara says.

This is usually true. The Food and Drug Administration recently approved the over-the-counter sale of Plan B to women and men 18 and older. EC can also be purchased over-the-counter by people of all ages at some pharmacies in California, Washington, Alaska, Hawaii, New Mexico, Maine, Montana, New Hampshire and Massachusetts.

In other states, you can get EC by going to a clinic or by contacting your doctor for a prescription. Clinics are located in every state in the country. To find a clinic near you, go to www.not-2-late.com or call the Emergency Contraception Hotline at 1-888-NOT-2-LATE (668-2528).

Going to a clinic is just like a regular visit to the doctor, only you do not need your parents' permission. First, you'll fill out some paperwork and then wait to see a health care provider. He or she will ask you a few questions about what happened and why you are there.

The health care provider will usually either supply you with the pills or write a prescription so you can obtain them. Also, you can get a prescription for EC before an emergency happens, so you'll have them on hand, just in case. Emergency contraception is inexpensive. Plan B usually costs between $10 and $45. Most clinics will charge only what you can afford to pay and some health insurance companies will cover the cost.

You may also need to pay for a clinic visit, too, but this may also be what you can afford to pay (i.e., a sliding-scale fee). Make sure you ask the clinic about cost before you go.

Emergency contraception is not a method of birth control; it is for emergencies only.

The best way to avoid pregnancy and STDs is to abstain from all sex—oral, vaginal, and anal. If you decide to have vaginal intercourse, you should use both a condom and a hormonal form of birth control (like the Pill) to protect against pregnancy and most STDs.

Plus, Plan B is only 89-percent effective when taken within three days. Birth control pills are 89- to 99-percent effective when taken regularly and correctly.

"Take precautions while you're having sex, and if something happens, then go get EC," Tara says. "Don't use EC as an excuse [not to use birth control]. Take it only if you absolutely need it."