Emergency hormonal contraception is sometimes called "the morning after pill." It is actually a short course of oral contraceptives taken at a high dose. The exact regimen (the number of pills and the number of days) depends on the type of oral contraceptive used. All oral contraceptives contain hormones.
This high dose of hormones blocks the implantation of the fertilized egg in the uterus. In turn, this action reduces the chances of a woman becoming pregnant after unprotected sexual intercourse by 75% or more if the woman is not already pregnant, adequate doses are prescribed, and the woman follows the regimen as directed. To be considered a possible candidate for emergency contraceptive pills a woman should receive medical attention within 72 hours of unprotected intercourse. (In contrast, emergency contraception with an IUD may be possible 5-7 days after intercourse, see below.) The only known contraindication to emergency contraception is pregnancy.
There are no serious side effects, but the pills may cause nausea in 30 to 50% and vomiting in 15 to 20% of women. These side effects may be controlled by taking an anti-nausea drug such as dimenhydrinate (Dramamine). Frequently a doctor will give a prescription nausea medication, such as Compazine , at the same time as the emergency contraceptive pill. A woman may also experience breast tenderness and a temporary disruption of her menstrual cycle.
Both current products on the market include the progesterone hormone levonorgestrel. Preven uses four hormone pills, each of which supply estrogen alone with levonorgestrel. The other emergency contraception treatment approved by the Food and Drug Administration (FDA) is Plan B, which consists of two tablets of levonorgestrel only. This lower dose results in less nausea and vomiting. Levonorgestrel-only medication may be more effective and causes less nausea compared to the Preven product.
Emergency hormonal contraception has the same restrictions as the hormonal contraceptive pill. A woman with a history of stroke, heart attack, liver tumor, or breast cancer needs careful evaluation and counseling before taking emergency hormonal contraception. The pills do not protect a woman from sexually transmitted infections.
This strategy is not meant to be a long-term contraception. Once the emergency is over, a woman should receive proper counseling so that she can select an effective and appropriate contraceptive method to use on a regular basis if she continues to be sexually active.