Left-side flank pain before a period

Period-related cramps can spread from the lower abdomen into the back or sides and may follow a familiar pattern each cycle. Pain that feels higher in the flank, changes with movement, or follows lifting may be muscular. Kidney Stones can cause severe wave-like pain, while a Kidney Infection may cause flank pain with fever, chills, nausea, or urinary changes. A Urinary Tract Infection may cause burning or frequent urination. A late period or possible pregnancy changes the safety advice for one-sided pain.

Record the timing against your cycle, pain location, bleeding, urinary symptoms, bowel changes, and response to warmth or rest. Gentle heat and ordinary activity as tolerated may ease period-related discomfort. Use pain relief only if it is suitable for you and follow the label; ask a pharmacist if pregnancy is possible or you have kidney or stomach problems. Arrange review when the pattern is new, worsening, or repeatedly disruptive.

Seek urgent help for sudden severe one-sided pain, fainting, heavy bleeding, fever with flank pain, repeated vomiting, blood in urine, or inability to urinate. If pregnancy is possible, one-sided pain with bleeding, dizziness, or shoulder-tip pain needs prompt emergency assessment.

Ask whether the pattern fits menstrual pain, whether a pregnancy test or urine test is appropriate, and whether further examination is needed. Describe cycle timing, bleeding, fever, urinary symptoms, prior stones, and every medicine or supplement you use.