Left lower flank pain: what to know

Flank pain is felt between the ribs and hip, often toward the side or back. Pain from a kidney stone may be intense, wave-like, and travel toward the groin, sometimes with nausea or blood in the urine. Kidney infection can cause flank discomfort with fever, chills, nausea, or painful and frequent urination. A urinary tract infection may cause burning or urgency without reaching the kidney. Muscle strain is more likely after lifting, twisting, or exercise and may change with movement. Bowel or reproductive-organ problems can also be felt low on the left, so location alone cannot identify the cause.

Arrange medical advice if pain persists, returns, or is joined by urinary changes, fever, vomiting, or tenderness. Drink normally unless a clinician has told you to restrict fluids. Avoid taking leftover antibiotics or someone else’s medicine. Note the onset, severity, movement of the pain, urine appearance, bowel symptoms, fever, and any recent injury. A clinician may check your abdomen and back, test urine, and decide whether blood tests or imaging are appropriate.

Seek urgent care for severe or rapidly worsening pain, fever with flank pain, repeated vomiting, faintness, confusion, inability to pass urine, or visible blood in the urine. Emergency assessment is especially important when pain is accompanied by a rigid or very tender abdomen, weakness, or signs of dehydration. Pregnancy, one functioning kidney, or significant kidney disease lowers the threshold for prompt review.

Ask whether your symptoms fit a kidney stone, kidney infection, urinary tract infection, muscle problem, or another source. Ask which tests are needed, what pain relief is suitable for you, and which changes should lead to emergency care.