If a couple forgets to use their birth control method, or their method fails, emergency contraception can be used. Emergency contraception should not be used as an ongoing birth control strategy.
Emergency contraception can be used to prevent pregnancy after unprotected intercourse or the failure of another birth control method.
Emergency contraceptive pills (morning after pills) can be used up to 120 hours (three to five days) after unprotected sex, but the earlier they are used the better.
A post-coital IUD can also be inserted to prevent pregnancy. This can be done up to seven days after unprotected sex.
Neither of these methods helps protect you against sexually transmitted infections.
Emergency contraceptive pills (ECP)
Emergency contraceptive pills may contain estrogen and progestin, or progestin alone. These are the same hormonal drugs contained in some birth control pills but at a different dose. When used for emergency contraception, these hormones interfere with ovulation to prevent a pregnancy. They may also change the lining of the uterus so a fertilized egg cannot implant. These pills are not perfect, but they cut the risk of pregnancy by 75 to 85 per cent.
Emergency contraception pills (ECP) are now available from pharmacists over the counter, without a doctor’s prescription, across Canada.
ECP is very safe. There is no evidence that these drugs cause harm to a pregnancy if they fail. You should not take the pills if you think you are already pregnant; they will not end a pregnancy that is already established.
Using the pills
Emergency contraceptive pills should be taken as soon as possible after unprotected intercourse.
If you have purchased the medication in advance, check the expiry date to make sure the pills are still good. ECP will not prevent a pregnancy from sex that happens after you take the pills, or that occurred more than 120 hours before.
ECP can make you throw up or feel nauseous. If you throw up within one hour of taking your dose of ECP, contact your pharmacy about getting another dose. To reduce nausea:
- try to eat something before taking the pills
- take a Gravol or other over-the-counter anti-nausea drug
- take the pills with milk not water
If your nausea is severe, your doctor may be able to prescribe a stronger anti-nausea drug.
Other possible side effects of ECP include:
- breast tenderness
Your next period will likely be on time, but it may be early or late. If you don’t have your period within three weeks of taking the ECP, visit your doctor or a pharmacy to have a pregnancy test done.
Emergency contraceptive pills are an emergency method used to cut the risk of pregnancy at one point in time. They should not be used as an ongoing method of birth control, but are effective as a back-up to other methods such as barriers or fertility awareness methods.
A post-coital IUD is also a very effective way of preventing pregnancy after unprotected sex. It is the same as a regular IUD and can be inserted up to seven days after intercourse. A post-coital IUD should not be used if a woman is also at risk of developing a sexually transmitted illness due to unprotected intercourse. Inserting an IUD when a woman has an infection can have serious complications.
This information is provided by Women’s College Hospital and is not intended to replace the medical advice of your doctor or health care provider. Please consult your health care provider for advice about a specific medical condition. This document was last reviewed on: Oct. 29, 2014