What causes flank pain on the left side?

Pain that worsens with twisting, lifting or pressing the area may be muscular. A kidney stone can cause severe, wave-like pain that travels towards the groin, sometimes with nausea or blood in the urine. A kidney infection may cause flank pain with fever, chills, feeling unwell, or painful and frequent urination. Bladder urinary tract infection symptoms can occur without flank pain, but pain higher in the side raises concern for kidney involvement. Digestive, nerve and skin conditions can also produce pain in this region.

Record when the pain started, whether it comes in waves, and what movement or position changes it. Note fever, urinary changes, vomiting, bowel symptoms or a rash. Drink normally unless a clinician has given you a fluid restriction, and avoid taking leftover antibiotics. A clinician may examine your abdomen and back and request urine testing or imaging based on the pattern.

Seek urgent care for severe or rapidly worsening pain, fever with flank pain, repeated vomiting, faintness, confusion, inability to pass urine, or blood in the urine. Prompt assessment is also needed during pregnancy or after a significant injury. Emergency help is appropriate if pain occurs with chest pain, difficulty breathing or collapse.

Ask whether the location and timing suggest a kidney, muscle or digestive cause, whether urine testing is needed, and which pain relief is safe for you. Mention prior stones, urinary infections, pregnancy and recent exertion.