Can the morning after pill make you miss your period?

Period can be late: Emergency contraception can have side effects including nausea (loss of appetite), vomiting, breast tenderness, fatigue, headache-- or cause your period to be early or late. These symptoms go away within a day or so after taking. If your period doesn't come by a week after you expected it, a pregnancy test might be a good idea, as emergency birth control isn't perfect.