America's 1st over-the-counter birth control pill is coming soon. Here's what to know about Opill

The Food and Drug Administration's 2023 approval of the first over-the-counter birth control pill, called Opill, broadened the options for people seeking to prevent pregnancy.

On March 4, 2024, the pill's manufacturer, Perrigo Company, announced that it has started shipping Opill and that consumers can expect to see it on shelves by the end of the month.

The Conversation asked Sarah Lynch, a pharmaceutical expert from Binghamton University, State University of New York, to answer some of the key questions people have about the new over-the-counter contraceptive.

How does Opill work to prevent pregnancy?

Opill contains norgestrel, which is a synthetic form of the hormone progesterone. Progesterone works in several ways to prevent pregnancy. First, it thickens the mucus in the cervix, which makes it challenging for sperm to enter the uterus and fertilize an egg. Second, it thins the lining of the uterus, making it less hospitable for a fertilized egg to implant. And third, it can prevent ovulation, or release of the egg, in most people.

Opill, like many other progestin-only birth control pills, must be taken at the same time each day to prevent pregnancy. This is because progestin levels must remain high in order to be effective.

If an Opill dose is taken even three hours late, or if vomiting or diarrhea occurs within four hours of taking the dose, a person should avoid intercourse or use some form of nonhormonal contraception for two days. Even though it only takes about two days for the drug to build up to an effective level, sperm can remain fertile in the female reproductive tract for up to five days after intercourse, meaning that it is important to take this medication regularly both before and after unprotected intercourse.

How effective is Opill?

When used exactly as instructed, Opill is 98% effective. This makes it the most effective nonprescription contraceptive option.