Primary Dysmenorrhea: This condition is the most common cause of menstrual cramps and is often accompanied by nausea. It is caused by uterine contractions induced by prostaglandins, leading to ischemic pain.

Irritable Bowel Syndrome (IBS): Although not directly related to menstruation, IBS can exacerbate during menstrual periods, leading to crampy abdominal pain and nausea.
Pregnancy: Early pregnancy can cause nausea and cramping, which might be mistaken for menstrual cramps.
Endometriosis: A condition where tissue similar to the lining inside the uterus grows outside of it, leading to painful periods, nausea, and other symptoms.

Ectopic Pregnancy: A life-threatening condition where the embryo implants outside the uterus, causing severe abdominal pain, nausea, and potentially leading to rupture and hemorrhage.
Appendicitis: Inflammation of the appendix can cause abdominal pain, nausea, and vomiting. Although not directly related to menstruation, its symptoms can sometimes be confused with menstrual cramps.
Ovarian Torsion: A rare but emergency condition where the ovary twists around its ligaments, cutting off blood supply, and causing severe pain and nausea.

Adenomyosis: A condition where tissue similar to the lining inside the uterus grows into the muscular walls of the uterus, leading to painful and heavy periods.
Pelvic Inflammatory Disease (PID): An infection of the female reproductive organs that can cause chronic pain, nausea, and other symptoms.
Interstitial Cystitis: A condition causing bladder pressure, bladder pain, and sometimes pelvic pain, which can be exacerbated during menstruation.