Can kidney stones cause back or flank pain rather than belly pain? 

Yes, kidney stones most commonly cause pain in the back or the flank (the side of the body between the ribs and the hip) rather than the ‘belly’ or central abdomen. While the pain can eventually radiate toward the lower abdomen and groin, its origin is typically in the renal area of the back. This is because the kidneys are ‘retroperitoneal’ organs, meaning they sit behind the abdominal cavity, closer to the muscles of the back. In the UK, clinicians use the location and nature of this pain to differentiate kidney stones from other conditions like appendicitis or muscle strain. 

What We will cover in this Article 

• Why kidney stone pain starts in the back and flank 

• The path of ‘referred pain’ as a stone moves 

• Distinguishing flank pain from a simple back muscle strain 

• Why kidney stones rarely cause central ‘belly’ pain 

• Common triggers that cause a stone to shift 

• A comparison table of kidney pain versus other abdominal issues 

Why the Flank and Back are Primary Locations 

The kidneys are situated high in the abdominal cavity, tucked under the diaphragm and protected by the lower ribs. Because they are positioned toward the back of the body, any inflammation or pressure within the kidney such as that caused by a stone is felt most acutely in the flank and lower back. 

When a stone blocks the flow of urine, the kidney begins to swell, stretching the sensitive capsule that surrounds it. These stretching triggers the ‘flank pain’ that is so characteristic of renal colic. While many people expect ‘organ pain’ to be felt in the front of the stomach, the anatomical position of the kidneys ensures that the first signals of trouble usually appear in the side or the back. 

• Retroperitoneal Position: The kidneys sit behind the digestive organs, closer to the spine. 

• Renal Capsule Stretching: The pressure from a blockage is felt in the nerves of the back. 

• Flank Tenderness: The area just below the ribs (the costovertebral angle) is often sensitive to touch during an attack. 

The Path of Radiation: ‘Loin to Groin’ 

While the pain starts in the back, it does not always stay there. As the kidney stone is pushed by the body out of the kidney and into the ureter (the tube connecting to the bladder), the location of the pain shifts in a predictable pattern known as ‘loin to groin’ radiation. 

As the stone moves lower down the ureter, the pain travels from the flank toward the lower abdomen and finally into the groin or genitals. This is known as ‘referred pain’, where the brain perceives the pain in a different location than the actual source due to shared nerve pathways. By the time a patient feels pain in their ‘belly’ or lower abdomen, the stone has often already moved significantly through the urinary tract. 

• Upper Ureter: Pain remains concentrated in the flank and back. 

• Middle Ureter: Pain shifts toward the side of the lower abdomen. 

• Lower Ureter/Bladder Junction: Pain is felt most intensely in the groin, labia, or testicles. 

Causes and Triggers of Stone Dislodgement 

A stone can sit quietly in the kidney for a long time without causing any back or flank pain. The ‘attack’ is triggered when the stone shifts and creates a physical obstruction. 

The most frequent cause of this shift is the stone becoming dislodged and entering the ureter. Because the ureter is much narrower than the kidney’s internal chambers, the stone gets stuck. This blockage causes the ureter to spasm and the kidney to distend with trapped urine. Triggers for this movement can include sudden changes in hydration, which alters the pressure within the kidney, or jarring physical movements like running or jumping. 

• Physical Obstruction: The stone stops the flow of urine, creating backpressure. 

• Involuntary Spasms: The muscular walls of the ureter contract violently to move the stone. 

• Inflammation: The jagged edges of the stone irritate the lining of the urinary tract. 

Differentiating Flank Pain: Stones vs. Other Issues 

Because the back and flank are common sites for various aches, it is important to distinguish kidney stone pain from other conditions that might feel similar. 

Feature	Kidney Stone Pain	Muscle Strain	Kidney Infection
Location	Flank/Back to Groin	Localised muscle	Flank and Back
Pain Nature	Intense waves (Colic)	Constant dull ache	Constant deep ache
Movement	Restless/Pacing	Worse with movement	Painful but still
Other Signs	Blood in urine	No urinary symptoms	Fever and chills

To Summarise 

Kidney stones are much more likely to cause back and flank pain than central belly pain because of the kidneys’ position at the back of the abdomen. While the pain can move toward the lower stomach and groin as the stone travels, the primary sensation is one of deep, intense pressure in the side or flank. Recognizing this ‘loin to groin’ pattern is essential for distinguishing renal colic from other types of back or abdominal pain and ensuring you get the correct medical assessment. 

If you experience severe, sudden, or worsening symptoms, such as intense pain in your side, blood in your urine, or a high fever with chills, call 999 immediately. 

Authority snapshot 

This article was reviewed by Dr. Stefan Petrov, a UK-trained physician with an MBBS and postgraduate certifications including ACLS and BLS. Having worked in emergency care and general surgery within the NHS, Dr. Petrov has diagnosed and managed hundreds of patients presenting with acute flank pain. This guide follows the clinical standards set by NICE and the British Association of Urological Surgeons to ensure accurate and safe information for patients.