Right flank pain during a period: what to know

Menstrual cramps usually begin around bleeding and may spread into the lower back or sides as the uterus contracts. Pain that is clearly linked to the cycle can still have another explanation, particularly when it is new, one-sided, severe, or lasts beyond the period. Kidney infection commonly presents with flank pain plus fever, chills, nausea, or painful urination. Kidney stones may cause intense, wave-like pain that travels toward the groin. A urinary tract infection can cause burning, urgency, or frequent urination, although flank pain with fever needs prompt attention.

Note the first day of bleeding, pain intensity, movement or urination triggers, discharge, fever, bowel changes, and whether pregnancy is possible. This pattern helps a clinician distinguish menstrual pain from urinary, muscular, or pelvic causes.

Rest, use gentle heat on the sore area, and keep fluids steady. Light movement may ease muscle tightness, but stop if it increases pain. If you normally use an over-the-counter pain reliever, follow its label and check with a pharmacist if you have kidney disease, stomach ulcers, take blood thinners, or could be pregnant. Keep a cycle and symptom record, including whether the pain returns each month or appears between periods.

Seek urgent care for sudden severe one-sided pain, fainting, heavy bleeding, fever with chills, repeated vomiting, painful urination with flank pain, or pain when pregnancy is possible. Arrange a medical review when pain is new, worsening, recurrent outside menstruation, or not improving after the period. Do not assume cycle timing explains a symptom that is markedly different from your usual cramps.

Does the timing suggest menstrual pain or another source? Should I have urine testing or a pregnancy test? Which pain medicines are appropriate for me? What symptoms would require urgent review?