A condom is a barrier contraceptive device used to prevent pregnancy and reduce transmission of sexually transmitted infections. They are highly recommended for their indication and work relatively well, however like most things, nothing is perfect 100 % of the time. Condoms, when used exactly as directed have a 1-2% risk of failing per year. Most of this comes from condom breakage or slippage after or during sex.
In addition, if condoms are used improperly, the failure rate goes up to 10-14% of failure per year.
That being said, condoms are very effective in birth control and reduction of sexually transmitted infections. Many times, causes for failure can be readily detected. For example, you and/or your partner will notice if a condom breaks or slips off. If that is the case, then an emergency contraception
pill (also known as the "morning after pill," or "plan B pill") can be used within 48 hours of intercourse to try to minimize the likelihood of becoming pregnant. Such emergency contraceptive pills can be obtained from a local pharmacy and do NOT require a prescription if the patient is 18 years old. Patients 16 and under require a prescription.
Please consult your primary care physician/pediatrician/sex counselor for further details or questions regarding condoms, emergency contraception, as well as other forms of contraception such as the birth control pill, Intrauterine devices, etc.