Flank pain is discomfort felt on either side of the body between the lower ribs and upper hip, usually towards the side or back. It may arise from kidney stones, a kidney infection, urinary obstruction, muscle strain or another nearby organ. Severe, persistent pain or pain with fever, vomiting or urine changes needs medical assessment.
Key Takeaways
- Kidney stones, kidney infections, urinary blockage and muscle strain are common causes of flank pain.
- Pain that comes in waves and spreads towards the groin may occur with a kidney stone.
- Flank pain with fever, chills, vomiting or painful urination may indicate a kidney infection.
- Blood in the urine, inability to pass urine or sudden unbearable pain requires urgent evaluation.
- The location of pain alone cannot confirm the cause; examination and tests may be needed.
- Treatment should target the underlying condition rather than rely only on repeated pain relief.
When is flank pain an emergency? Seek urgent care for severe or rapidly worsening pain, high fever, shaking chills, repeated vomiting, blood in the urine, inability to urinate, fainting, confusion, pregnancy, a single functioning kidney, or a cold and very weak patient. Visit
Emergency Medicine at Renova Hospitals or call 040 2333 3333.
Where Is the Flank Located?
The flank is the area on the side of the body between the lowest ribs and the pelvis. Pain may occur on the right, left or both sides. It may stay in one spot or spread towards the abdomen, groin, hip or lower back. Because the kidneys lie towards the back under the ribs, kidney pain is often felt deeper than surface muscle pain, but symptoms can overlap.
What Are the Common Causes of Flank Pain?
Can Kidney Stones Cause Flank Pain?
Yes. Kidney stones can cause sharp pain in the back or side that may move towards the lower abdomen or groin. The pain may come in waves as the urinary tract contracts around the stone. Nausea, vomiting, frequent urination, painful urination or blood in the urine may also occur.
Patients with suspected stones may need evaluation by a
urologist at Renova Hospitals, especially when pain is severe, urine flow is reduced or blood is visible in the urine.
Can a Kidney Infection Cause Flank Pain?
A kidney infection can cause pain in the back, side or groin together with fever, chills, painful or frequent urination, cloudy or foul-smelling urine, nausea or vomiting. Kidney infections need timely medical treatment because infection can spread to the bloodstream or damage the kidney.
Can Urinary Blockage Cause Pain in the Side?
A stone, narrowing, enlarged prostate or another blockage can interfere with urine flow and produce flank pain. Some people also notice reduced urine output, urinary urgency, swelling or repeated urinary infections. Obstruction with infection can become an emergency and may require a procedure to drain the urinary tract.
Can Muscle Strain or Back Injury Cause Flank Pain?
Yes. Strained muscles around the back, ribs or abdomen may cause flank discomfort after lifting, exercise, coughing, twisting or an awkward movement. Muscular pain often worsens with movement, deep breathing or pressure over the affected area and may improve with rest. Persistent or severe pain still requires assessment because kidney and muscle pain can feel similar.
What Other Conditions Can Cause Flank Pain?
- Spinal disc, joint or nerve problems
- Shingles, especially when burning pain is followed by a rash
- Gallbladder, liver, bowel or pancreatic conditions
- Lung or chest-wall problems
- Kidney cysts or less common kidney disorders
- Trauma involving the ribs, abdomen or urinary tract
Because several organs are close to the flank, the cause should be evaluated rather than assuming every pain in this area is a kidney problem.
How Can You Tell Kidney Pain From Muscle Pain?
Kidney-related pain is often felt deeper under the ribs and may occur with urine changes, fever, nausea or pain moving towards the groin. Muscle pain is more likely to follow lifting or unusual movement and may be tender when pressed. These patterns are useful clues but are not reliable enough to make a diagnosis without an examination.
What Symptoms May Occur With Flank Pain?
- Fever or chills
- Burning or pain while urinating
- Frequent or urgent urination
- Blood, cloudiness or unusual smell in the urine
- Nausea or vomiting
- Pain spreading to the abdomen or groin
- Tenderness or pain with movement
- Reduced urine output
- A new rash or numbness
How Is Flank Pain Diagnosed?
The doctor will ask when the pain started, whether it is constant or comes in waves, where it spreads and whether urinary, digestive, respiratory or movement-related symptoms are present. The abdomen, back and flank may be examined for tenderness, swelling or muscle spasm.
Depending on the suspected cause, tests may include:
- Urine analysis to look for infection, crystals or blood
- Blood tests to assess infection, kidney function and dehydration
- Ultrasound of the kidneys and urinary tract
- CT imaging when a stone, obstruction or another internal cause is suspected
- Other imaging or specialist tests based on the examination
What can a doctor check? A
General Medicine physician may begin the assessment and coordinate urine tests or imaging. A
urologist may manage stones or urinary obstruction, while a
nephrologist may assess kidney-function problems or medical kidney disease.
How Is Flank Pain Treated?
Treatment depends on the cause. A kidney infection generally requires prescribed antibiotics. Kidney stones may be managed with clinician-approved pain relief, hydration guidance and medicines in selected cases, while larger or obstructing stones may require a procedure. Muscle strain may improve with activity modification, physiotherapy and pain relief that is safe for the individual patient.
Do not repeatedly self-medicate with antibiotics or strong painkillers without a diagnosis. Some pain medicines may be unsafe for people with kidney disease, stomach ulcers, heart disease, pregnancy or other conditions.
What Can You Do at Home While Waiting for Evaluation?
- Rest from strenuous activity if a muscle injury is possible.
- Drink fluids normally unless a doctor has restricted your intake.
- Monitor temperature and urine for blood, cloudiness or reduced output.
- Use only pain medicines that are safe for you and recommended by a healthcare professional.
- Do not delay care if pain is severe, worsening or accompanied by fever or vomiting.
When Should You Consult a Doctor?
- Pain lasts more than a few hours or keeps returning
- Pain interferes with sleep or routine activity
- There is burning urination, urgency or urine colour change
- Fever, chills, nausea or vomiting develops
- You have kidney disease, a single kidney or are pregnant
- Home treatment is not improving the pain
Consult a Physician, Urologist or Nephrologist at Renova Hospitals
Medical References
Medically Reviewed & Approved By:
Dr. Philip Padmakar Nethagani
Urology, Kidney Transplantation, Robotic Surgery & Pediatric Urology
MBBS, MS (General Surgery), MCh (Urology), DNB (Urology)
This article has been reviewed and approved by a qualified medical professional to ensure accuracy, credibility, and adherence to current clinical standards.