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Emergency Contraception: What You Need To Know

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Written by Dr. Nancy Durand, a gynaecologist at Sunnybrook with a clinical and research interest in minimally invasive surgery, HPV and colposcopy.

It's something many women can relate to: concern about an unplanned pregnancy following unprotected sex or failed birth control.

Oral emergency contraception, containing the hormone levonorgestrel -- and known in Canada as "plan B" -- is a safe option for women to prevent pregnancy. The hormonal contraception works by preventing the release of an egg and preventing implantation of a fertilized egg within 72 hours of unprotected sex. The drug won't affect an already implanted egg or an established pregnancy (it's not an abortion drug). If taken within 24 hours of unprotected sex, it is 95 per cent effective at preventing pregnancy.

Available in Canada without a prescription in the family planning area of most pharmacies, it is convenient and there are no restrictions related to age or gender, which means a friend, family member or partner can pick it up for you.

Emergency contraception tips

Act quickly
Go to your nearest pharmacy as soon as you can following unprotected sex. It's true that emergency contraception can be taken up to 72 hours after unprotected sex, but it is more effective the sooner you take the pill.

Expect mild side effects
In many women, nausea is the most common side-effect. Ask the pharmacist about an anti-nausea medication you can take before or with the emergency contraception. You may also experience mild abdominal pain, fatigue, headache and menstrual changes.

Period shake-up
While most women will have a normal period the next month following emergency contraception, the hormones can change how long your period lasts and also the timing (it may come a week earlier or a week later). If your period is late, you should consider taking a pregnancy test.

BMI considerations
Recently there have been reports about emergency contraception not being as effective for women with a body mass index (BMI) over 25. While there is some evidence to show that emergency contraception may be less effective as BMI increases, this should not discourage women of any weight from taking this safe and accessible medication. That said, it may be worth visiting your doctor or local sexual health clinic to speak about getting an IUD, which is a very effective way to prevent pregnancy in any woman.

STI testing
While very effective at preventing pregnancy, emergency contraception does not protect against sexually transmitted infections, including HIV. It is wise to use condoms to reduce the transmission of STIs even if you're using hormonal birth control. If you're worried, please visit your family physician or health clinic to talk about STI testing.

Time to reflect
As emergency contraception should be approached as an occasional option for preventing pregnancy, it's a good time to think about a regular and reliable birth control strategy. Talk to your doctor -- there are many contraception options available.

If you're a parent of a teen who has recently had unprotected sex, please seize the opportunity to open the dialogue on sexuality and birth control. Teens are often more sexually active than we think, and supportive parents and your health care team can help.

Read more sexual health information for women from Sunnybrook experts at

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