The morning after pill is actually a series of pills containing high dose hormones which are used to end the early stages of cell division after unprotected sexual contact. The morning after pill is effective when used appropriately at terminating the earliest stages of cell division in a fertilized egg, preventing ovulation, or causing an uninhabitable environment for a fertilized egg in the uterine lining which will cause in effect a miscarriage.
The morning after pill is also referred to as emergency contraception. It contains high dose ingredients very much like that of regular birth control pills. Depending on the prescription brand, this can be very high doses of estrogen or very high doses of progesterone. Sometimes very high doses of a combination of these effective hormones are used but this is more controversial, as there are health effects associated with both hormones taken in such high doses that using a combination pill increases the chance of side effects.
The idea of emergency contraception began as a failsafe against potential pregnancy in cases of rape, incest, and in cases of potential pregnancy in people with severe mental disabilities like mental retardation who were suspected of having sexual intercourse. It is called the morning after pill indicating the time frame required for its effective use. Waiting too long after sexual contact increases the risk of deforming a fetus yet bringing it to term or aborting it along the way.
The morning after pill should only be used under the guidance of a physician. While some people use their own birth control pills, or simply use their birth control pills in high doses after sexual contact and refuse to take them regularly, this can lead to serious health complications, birth defects, and in some cases, death. A medical professional has the expertise to explain how much to take and for how long and also has the ability to warn the patient against serious side effects.
The morning after pill is not intended to be used as a chronic form of birth control, and using it in this manner may have serious side effects or cause long term health complications. While the American Food and Drug Administration has approved birth control pills for the use of emergency contraception, testing on the safety of long term use has been inconclusive at best.
Symptoms such as nausea, vomiting, breakthrough bleeding, and breast tenderness or pain are common but are usually annoying but not life threatening. Symptoms such as atopic pregnancy and the formation of blood clots can be life threatening. Infertility is a possible side effect and studies have not been able to confirm or deny that the chronic use of the morning after pill will increase the likelihood of cancers like breast, uterine, or ovarian as well as other hormone dependant cancers.
When used properly, the morning after pill will effectively guard against pregnancy. It will not however, under any circumstances, guard against any type of sexually transmitted disease including HIV.