There are two forms of emergency contraception — over-the-counter and prescription pills you take orally and intrauterine devices (IUDs) that a healthcare professional inserts.



This article primarily focuses on emergency contraceptive pills.



Although experts understand that a person’s weight or body mass index (BMI) can affect the effectiveness of emergency contraceptive pills, clinical research hasn’t yet established a threshold for efficacy.



That means healthcare professionals currently don’t have a concrete answer as to when emergency contraceptive pills become less effective or ineffective.



Experts need more research to understand whether doubling the dose can increase efficacy in people with a higher weight or BMI.



The copper IUD can be the most effective form of emergency contraception, regardless of weight or BMI.



If you have the option, talking with a healthcare professional may be helpful. They can recommend the best emergency contraceptive for your individual needs