Flank pain worse when lying down: what to know

The flank is the area between the upper abdomen and back. Pain that changes with posture, twisting, lifting, coughing, or pressing the area often points toward muscles, joints, or the ribs. A kidney problem may cause deeper pain in the side or back and can occur with burning urination, frequent urination, cloudy or bloody urine, fever, chills, nausea, or pain that comes in waves. A symptom pattern cannot identify the cause by itself.

Notice when the pain began, which position makes it better or worse, and whether movement or touch changes it. Rest from heavy lifting, try a supported sleeping position, and use gentle movement if it does not increase pain. Drink normally unless a clinician has told you to restrict fluids. Do not start leftover antibiotics or assume that a pain medicine is suitable if you have kidney disease, stomach ulcers, are pregnant, or take other medicines.

Seek urgent help for severe or rapidly worsening pain, fever with flank pain, repeated vomiting, fainting, confusion, inability to pass urine, or visible blood in the urine. Arrange a prompt appointment if the pain persists, repeatedly wakes you, follows an injury, or is accompanied by urinary changes. A clinician may examine your back and abdomen and check urine, with further tests guided by the findings.

Could the pain be coming from my muscles, ribs, spine, or urinary system? Which symptoms would make testing urgent? Should I change any medicine or activity while the cause is being assessed?