Does urine smell with kidney infection?

Kidney infections, also known as pyelonephritis, often cause changes in the smell of urine. A strong, unpleasant odor is a common symptom. Understanding what’s normal and what’s not can help identify a potential kidney infection.

What causes urine to smell with a kidney infection?

Healthy urine has little to no smell. But with a kidney infection, bacteria and pus can alter urine odor in the following ways:

  • A strong, unpleasant smell, often described as fishy.
  • A foul or ammonia-like smell.
  • A sweet, fruity odor in urine.

These happen because the infection causes an overgrowth of bacteria in the kidneys and urinary tract. This bacteria releases gases that contain sulfur or ammonia, leading to strong odors.

Sometimes the smell resembles ammonia because urea, the waste in urine, breaks down into ammonia. Bacteria speeds up this breakdown. Certain strains also split urea into sulfur compounds, causing a foul rotten egg smell.

An overwhelmed kidney may not fully filter waste. This allows abnormal metabolic byproducts into the urine, creating a sweet, fruity scent in some cases.

When does urine smell indicate an infection?

While urine smells stronger with a kidney infection, don’t rely on smell alone. Smelly urine without other symptoms may not signal an issue. But if any of the following accompany foul-smelling urine, see a doctor promptly:

  • Burning or stinging during urination
  • Urinating more or less frequently
  • Cloudy, bloody, or dark urine
  • Pressure or pain in the back/sides
  • Nausea, fever, chills

These are common signs of a possible kidney infection. The combination of these symptoms with foul smelly urine makes an infection very likely.

Can certain foods or vitamins change urine odor?

Yes, certain foods, vitamins, and medications can temporarily affect urine smell. For example:

  • Asparagus – Results in a sulfur-like smell in urine.
  • Curry, garlic, onions – Causes a pungent odor.
  • Vitamin B6 – At very high doses, makes urine smell odd.
  • Fenugreek – Causes a maple syrup-like odor.

But these dietary changes cause only mild, temporary smell changes. With a kidney infection, the urine smells much more foul and persistent.

When to see a doctor

See a doctor promptly if you notice any of the following:

  • Urine has a very strong or foul odor
  • It smells fruity or sweet
  • Smell is accompanied by other UTI symptoms
  • Odor persists despite hydration changes
  • You have risk factors like frequent UTIs or diabetes

Quick medical attention provides the best outcomes. Put off treatment, and the infection can permanently damage the kidneys.

Diagnosing smelly urine from infection

To check for kidney infection, the doctor will:

  • Discuss symptoms – Ask about urine smell, pain, frequency, other changes.
  • Collect a urine sample – Test for bacteria, blood, pus, abnormal pH.
  • Order blood work – Check kidney function, electrolyte levels, and white blood cell count.
  • Take a medical history – Consider risk factors like past UTIs, diabetes, or kidney stones.
  • Perform imaging – Use CT, MRI, or ultrasound to assess kidney structure.

These help confirm an infection and pinpoint any complications. Testing also identifies the type of bacteria causing it.

Treating smelly urine from kidney infection

Treatment aims to eliminate infection and prevent kidney damage. It involves:

  • Antibiotics – Oral or IV medications that fight the bacterial infection.
  • Pain relievers – NSAIDs or other medications to ease discomfort.
  • Hydration – Drinking more fluids flushes out bacteria.
  • Probiotics – Restore healthy bacteria to prevent recurrent UTIs.
  • Follow-up testing – Ensure the infection clears and doesn’t recur.

With prompt treatment, foul-smelling urine goes away in a few days. More serious kidney infections may require a hospital stay for antibiotics and IV fluids.

Can smelly urine be prevented?

It’s difficult to prevent individual kidney infections entirely. But the following healthy habits lower the risk:

  • Drink plenty of fluids, especially water.
  • Urinate as soon as the need arises.
  • Wipe front to back after using the restroom.
  • Avoid potentially irritating feminine products.
  • Don’t delay urination.

Cranberry juice and probiotics may also help prevent recurrent UTIs that can lead to kidney infection. Talk to a doctor about other preventive options.

When to call a doctor about smelly urine

Contact your doctor right away if urine smells foul and you have any of the following:

  • Burning sensation or pain when urinating
  • Need to urinate more or less often
  • Lower back or abdominal pain
  • Nausea, vomiting, fever, or chills
  • Fatigue, confusion, or weakness

These may indicate a kidney infection that requires prompt treatment. Catching it early is crucial to prevent complications.

Let the doctor know about any recent UTI symptoms and if urine smells fruity, sweet, or ammonia-like. Also report any pain, which could signal an obstruction like a kidney stone.

When smelly urine may not need immediate care

In some cases, foul urine odor may not need urgent care if:

  • It’s temporary after eating asparagus, curry, garlic or taking vitamins.
  • It started after beginning a new medication.
  • It’s sometimes present but mild and not accompanied by other symptoms.
  • It improves after drinking more fluids and urinating frequently.

But it’s still wise to call the doctor to discuss any persistent, very foul urine smells. Odor accompanied by other UTI symptoms always warrants prompt medical attention.

Tips for preventing smelly urine

Here are some tips to help prevent foul-smelling urine:

  • Drink plenty of fluids, especially water – This dilutes urine so smells are less concentrated.
  • Urinate when the need arises – Don’t delay so bacteria doesn’t overgrow.
  • Shower instead of bathe – Baths can introduce bacteria in the urethra.
  • Choose loose cotton underwear and avoid irritants – Tight clothes trap moisture that allows bacterial overgrowth.
  • Wipe front to back after using the restroom – This avoids spreading bacteria from the rectum to urethra.
  • Stay hydrated and urinate after sex – Flushes out any bacteria that may get introduced.

Practicing good hygiene, staying hydrated, and emptying the bladder frequently can reduce the risk of UTIs leading to foul smelly urine.

When to see a doctor for smelly urine

See a doctor right away if urine smells strongly of ammonia, rotten eggs, or something fruity or sweet. Also seek medical care if the smell coincides with:

  • Burning during urination
  • Increased frequency or difficulty urinating
  • Fever, chills, nausea, or vomiting
  • Pain in the abdomen, sides, or lower back
  • Cloudy, bloody, or dark urine

These symptoms suggest a possible kidney infection, which needs treatment promptly. Catching it early prevents the infection from permanently damaging the kidneys.


A kidney infection often makes urine smell foul, strong, or unusual. The odor stems from bacteria and excess waste in the urine. See a doctor right away if smelly urine occurs with other UTI symptoms like burning, increased frequency, pain, fever or chills. Prompt treatment prevents complications. Drink lots of fluids and practice good hygiene to reduce recurrent UTIs that can cause smelly urine.

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