Emergency contraception (EC) offers a way to prevent pregnancy after unprotected sexual activity or when a primary contraceptive method fails. Many individuals using daily hormonal birth control pills may wonder if EC remains a viable option. This article clarifies how EC works and how its use can be navigated alongside ongoing hormonal birth control.
Understanding Emergency Contraception Options
Two primary types of oral emergency contraception are widely available: levonorgestrel-based pills and ulipristal acetate pills. Levonorgestrel-based EC, often known by brands like Plan B One-Step, is available over-the-counter and is most effective when taken within 72 hours (three days) of unprotected sex, though it may be used up to 120 hours (five days) afterward. Its main action involves delaying or preventing ovulation, meaning it stops the release of an egg from the ovary.
Ulipristal acetate (UPA), commonly sold under the brand name ella, requires a prescription and can be effective for up to 120 hours (five days) after unprotected intercourse. This medication works by binding to progesterone receptors, which can postpone or inhibit ovulation even when it is imminent. Both types of EC are designed to prevent pregnancy and do not terminate an existing pregnancy.
Navigating EC Use While on the Pill
The interaction between emergency contraception and ongoing hormonal birth control pills depends on the type of EC used. If taking a levonorgestrel-based EC like Plan B One-Step, individuals can generally continue their regular birth control pills as usual without concern for reduced effectiveness of either medication. The hormones in the birth control pill do not diminish the efficacy of levonorgestrel EC.
Ulipristal acetate, however, has a different interaction due to its mechanism of action as a progesterone receptor modulator. Hormonal contraceptives, including the pill, contain progestin, which could theoretically compete with ulipristal acetate for progesterone receptors. Research indicates that initiating hormonal contraception too soon after taking ulipristal acetate may reduce the effectiveness of ulipristal acetate in delaying ovulation. Therefore, it is generally recommended to wait at least five days after taking ulipristal acetate before resuming or starting any hormonal birth control pills. This waiting period helps ensure ulipristal acetate can exert its full effect.
Guidance After Taking EC
After taking emergency contraception, particularly while on a birth control pill, certain steps are important for continued pregnancy prevention. If a levonorgestrel EC was used, it is safe to resume or continue your regular birth control pills immediately. However, it is advisable to use a backup barrier method, such as condoms, for at least seven days following the EC dose, especially if the EC was taken due to missed birth control pills.
For those who took ulipristal acetate, it is important to wait five full days before restarting any hormonal birth control. During this five-day interval and for a period afterward, non-hormonal backup contraception like condoms should be used for any sexual activity. This provides protection while waiting to resume the hormonal pill and until its contraceptive effects are re-established.
Following EC use, changes to the menstrual cycle are common, including periods that may be earlier, later, lighter, or heavier than usual. Mild side effects such as headache, nausea, fatigue, and abdominal pain are also possible. If a period is missed by more than a week, or if severe symptoms or persistent unusual bleeding occur, seeking medical consultation for a pregnancy test or further evaluation is recommended.