Pain on the left flank of the body: what to know

The flank is the area between the ribs and hip on the side of the back. A strained muscle may hurt more when you twist, lift or press the area. Kidney stones can cause severe pain that comes in waves and may move towards the groin. A kidney infection can cause flank pain with fever, chills, nausea or urinary symptoms. Burning urine, frequent urination or cloudy urine can occur with a urinary tract infection, although flank pain with fever needs prompt assessment.

Record when the pain began, whether it is constant or wave-like, and what movements affect it. Drink normally unless a clinician has given you fluid restrictions. Rest from strenuous lifting, and use a wrapped heat pack for a suspected muscle strain. Do not start leftover antibiotics or take medicines that may be unsafe with kidney disease, pregnancy, ulcers or other conditions; ask a pharmacist about a suitable pain reliever. A clinician may check your abdomen and back, urine, temperature and kidney function.

Seek urgent medical help for sudden severe pain, fainting, confusion, repeated vomiting, a high fever with shaking chills, blood in the urine, inability to pass urine, or pain after a significant injury. Contact a clinician promptly if flank pain comes with fever or urinary symptoms, lasts despite rest, or keeps returning. Pregnancy, one functioning kidney, known kidney disease or immune suppression lowers the threshold for assessment.

Could the location and movement pattern suggest a muscle or spinal cause? Should my urine or kidney function be checked? Which pain medicines are safe for me, and what symptoms mean I should return urgently?