How effective is emergency contraception to use?

Very effective: Emergency contraception (ec) can be very effective if used properly. Ec can consist of a pill or pills or insertion of a copper iud. Depending on the regimen, the ec must be taken as soon as possible after unprotected sex and no more than 5 days later. Due to variations in timing and use, studies have shown the effectiveness of pill regimens to range from 50-90%. Failure rate for the iud is <1%.

Oral emergency: contraception. Plan B One-Step is up to 89 % effective when taken within 72 hours (3 days) after unprotected sex. It can reduce chance of pregnancy by up to 95% if used within 24 hours. It continues to reduce the risk of pregnancy up to 120 hours (5 days) after unprotected sex, but is less effective as time passes.

85-97%: effective if taken within 72 hours.(more effective if taken within 24 hours.)

About 95%: The sooner you take the medication after the event the more effective it is--about 95% or so. To be effective, it is recommended to be used as soon as possible, up to 72 hours after the relation. If you have any additional concern, consult your doc. Good luck.

Efficacy: Levonogestrel pills can reduce your risk of pregnancy by up to 95% is used within 24 hours of sex. They are up to 89 percent effective when taken within 72 hours (three days) after unprotected sex. They continue to reduce the risk of pregnancy up to 120 hours (five days) after unprotected sex, but they are less effective as time passes.