Kidney Stones or Urine Infection? 7 Signs That Can Help You Tell the Difference

Pain while urinating, discomfort in the lower abdomen, or changes in urine can be alarming. Two common causes are kidney stones and urinary tract infections (UTIs). Although they can sometimes produce similar symptoms, the underlying problems are very different and require different treatments.

A kidney stone is a hard deposit that forms inside the kidneys and may move through the urinary tract. A UTI occurs when bacteria infect part of the urinary system, usually the bladder or urethra. If the infection reaches the kidneys, it becomes a kidney infection, which can be more serious.

According to Dr Shashank M S, Consultant, Urology and Renal Transplant, Aster CMI Hospital, Bangalore, knowing the differences can help people recognise when medical attention is needed.

1. Where Does The Pain Occur?

The location of pain is one of the most useful clues.

Kidney stones commonly cause sudden, severe pain in the side or back, often below the ribs. The pain may move towards the lower abdomen or groin as the stone travels through the urinary tract.

A UTI, particularly a bladder infection, more commonly causes discomfort or pain in the lower abdomen or pelvic area.

However, pain patterns can overlap, so location alone cannot confirm the cause.

2. What Does The Pain Feel Like?

According to research published in the Journal of Pioneering Medical Sciences, kidney stone pain can be extremely intense. It often comes in waves, with periods when the pain becomes severe and then eases slightly. This is known as colicky pain and occurs as the urinary tract contracts around the stone.

A bladder infection usually causes a more persistent discomfort or pressure in the lower abdomen rather than the severe, wave-like pain typically associated with a stone.

A kidney infection can cause a steady ache or pain in the back or side, usually along with other symptoms such as fever and chills.

3. How Does Urination Feel?

Burning or stinging when passing urine is strongly associated with a UTI.

People with a urine infection may also feel that they need to urinate frequently or urgently, even when only a small amount of urine comes out.

Kidney stones can also cause discomfort during urination, particularly when a stone is close to the bladder. However, burning and urinary urgency are generally more characteristic of a lower urinary infection.

4. What Does The Urine Look Or Smell Like?

Changes in urine can provide another clue. A UTI may cause urine to become:

• Cloudy
• Strong-smelling
• Darker than usual in some cases

Kidney stones can cause blood in the urine, making it appear pink, red, or brown. Sometimes the amount of blood is too small to be seen and is detected only through testing.

Blood in the urine can occur with infections and several other conditions, so it should not automatically be attributed to a kidney stone.

Also Read: Can Kidney Stones Cause Blood in Urine? Causes, Signs & When to See a Doctor

5. Are Fever And Chills Present?

This is an important difference. An uncomplicated bladder UTI does not always cause a high fever. But when infection spreads to the kidneys, symptoms can become more severe.
A kidney infection may cause:

• High fever
• Chills or shivering
• Back or side pain
• Weakness
• Nausea
• Vomiting

A kidney stone by itself does not usually cause fever. Fever in someone with severe kidney stone pain is particularly concerning because it may indicate an infection alongside the obstruction, such as obstructive pyelonephritis, according to a study published in the International Journal of Emergency Medicine.

An infected, blocked kidney can become dangerous and needs urgent medical attention.

6. Do Nausea And Vomiting Occur?

Severe nausea and vomiting are common with kidney stones, particularly when the pain is intense.

A kidney infection can also cause nausea and vomiting, especially when accompanied by fever, chills, and feeling generally unwell.

Therefore, vomiting by itself cannot distinguish between the two. The combination of symptoms is more useful.

For example, nausea, blood in the urine, and abdominal pain occurring altogether may suggest a stone, while fever, chills, back pain, and nausea may point more towards a kidney infection.

7. Is There Difficulty Passing Urine?

A kidney stone can sometimes become lodged in the urinary tract and block the flow of urine. This can lead to severe colicky pain and, depending on the location and degree of blockage, difficulty passing urine.

A UTI can cause frequent urges to urinate but does not typically cause complete obstruction.
Being unable to pass urine, particularly with severe pain, requires prompt medical attention.

Can You Tell The Difference From Symptoms Alone?

Not always.

Dr Shashank explains that kidney stones and urinary infections can produce overlapping symptoms, making testing important in some cases.

A doctor may recommend a urine test to look for signs of infection or blood. Blood tests can help assess infection and kidney function. Imaging, such as an ultrasound or CT scan, may be used when a kidney stone or urinary blockage is suspected.

This is particularly important when symptoms are severe, persistent, or unusual.

Also Read: Signs You May Have a Kidney Stone: Early Symptoms You Should Never Ignore

When Is Kidney Stone An Emergency?

A kidney stone does not always require an emergency procedure. Small stones may pass naturally and can often be managed with pain relief, fluids, and medical monitoring.

However, urgent assessment is needed if stone symptoms occur with fever, chills, or feeling very unwell. An infection trapped behind a blocked urinary tract can worsen rapidly and may require urgent drainage and antibiotics.

Repeated vomiting can also lead to dehydration and may make it impossible to take medicines or fluids.

How Are They Treated?

Treatment depends on the cause.

Uncomplicated urine infections are generally treated with appropriate medicines, often antibiotics when a bacterial infection is confirmed or strongly suspected.

For kidney stones, treatment depends on their size, location, and whether they are causing obstruction. Small stones may pass without a procedure, while larger or obstructing stones may require treatment to break up or remove them.

Pain control and appropriate fluid intake may also be part of treatment, depending on the individual situation.

Importantly, antibiotics do not dissolve kidney stones, while treating a suspected infection without proper assessment may not address an obstructing stone.

When To See a Doctor?

Seek medical attention promptly if urinary symptoms are accompanied by:

• High fever or chills
• Severe or worsening pain
• Repeated vomiting
• Difficulty passing urine
• Blood in the urine
• Severe weakness or feeling very unwell

These symptoms can indicate a more serious infection, obstruction, or another urinary problem.

Final Word

Sudden, severe pain in the side or back that travels towards the groin, particularly with nausea or blood in the urine, is more suggestive of a kidney stone. On the other hand, burning urination, frequent or urgent urination, cloudy urine, and lower abdominal discomfort are more typical of a urine infection. But the two conditions can overlap, worsening the condition. Do not wait for the symptoms to settle on their own; consult a doctor to identify the cause and ensure the right treatment.