The morning after pill typically lasts in your system for about 5 days, though this can vary depending on the type of pill, your metabolism, and other body functions. For example, levonorgestrel-based pills like Plan B have a half- life of about 27 hours and are usually cleared from the body within 5 to 6 days. Ulipristal acetate pills like Ella have an estimated half-life of about 32 hours. The pill works by preventing or delaying ovulation and changes in cervical mucus to reduce the chance of pregnancy. After about 5 days, the hormone levels from the pill reduce to negligible levels, meaning it is no longer effective for emergency contraception past this period.
