Menstrual blood

Why menstrual cramps happen

It’s common to feel discomfort around your abdomen, lower back, and thighs when you’re menstruating. During your period, the muscles of your womb contract and relax to help shed built-up lining. Sometimes you’ll experience cramps, which are your muscles at work. Some women and girls may experience nausea, vomiting, headaches, or diarrhea as well.