Period changes are the most common side effect of Plan B, so a delayed period does not automatically indicate pregnancy. Here’s a quick list of important points and expectations about emergency contraception:

• Available to anyone without a prescription at a drugstore (in the US)

• Needs to be taken within 72 hours (3 days) of unprotected sex

• Short-term side effects include breast tenderness, nausea and cramps

• Menstrual irregularities are also super common. Your next period can come early or late, and sometimes you might have spotting. 

• If you’ve not had a period 3 weeks after unprotected sex, it’s best to take a pregnancy test.