A urinary tract infection (UTI) can cause urine to smell foul, strong, or unusual. The most common urine smells caused by UTIs include:
Ammonia
Ammonia is a pungent gas that smells like household cleaners. When excess ammonia is present in urine, the urine may smell strongly of ammonia. This occurs when UTI bacteria like E. coli break down urea into ammonia.
Rotten eggs
UTI urine may smell like rotten eggs or sulfur. This is due to the presence of amino acids and volatile sulfur compounds, which smell like rotten eggs when concentrated in urine.
Maple syrup
Maple syrup odor in urine is due to the presence of maple syrup urine disease. This is a rare genetic disorder where the body cannot break down certain amino acids. The smell is caused by buildup of these amino acids in the urine.
Foul, fishy odor
Bacteria like E. coli can cause urine to smell foul or fishy. This occurs because the bacteria produce volatile compounds containing nitrogen or sulfur, which have a foul, fishy odor.
Sweet, fruity odor
A sweet or fruity odor, like pineapple, in urine can indicate uncontrolled diabetes leading to a buildup of ketones in the urine. Ketones have a sweet, fruity aroma.
Popcorn
Popcorn smelling urine can occur with a rare metabolic disorder called cystinuria. This causes a buildup of the amino acid cystine in urine, which smells like buttered popcorn.
Other unusual smells
Other less common urine odors associated with UTIs include foul meaty smell, cheese odor, chlorine smell, and scent of coffee.
When to see a doctor
Urine that smells abnormal consistently can be a sign of an underlying condition that requires medical attention. See your doctor if your urine regularly smells:
- Ammonia-like
- Like rotten eggs
- Fishy
- Sweet/fruity
- Like popcorn
- Foul and meaty
- Any other unusual smell
You should also see a doctor if the smelly urine persists despite treatment of a UTI. This could indicate a complicated infection or different health problem.
Causes
There are several possible causes of foul, strong, or unusual smelling urine with a UTI:
Bacteria
Bacteria are the most common cause of UTIs. Bacteria like E. coli and Klebsiella pneumoniae release chemicals during growth in the urinary tract that give urine a foul, fishy, or otherwise abnormal smell.
Diet
Foods like asparagus, onions, garlic, and cruciferous vegetables can cause urine to have a foul or strong smell due to the breakdown of sulfur-containing compounds.
Dehydration
Concentrated urine from dehydration has a stronger odor than dilute urine. Dehydration commonly occurs with UTIs due to increased urination and fluid loss from fever or vomiting.
Medications
Some medications like multivitamins can give urine an abnormal smell. Antibiotics used to treat UTIs can also contribute to foul-smelling urine in some cases.
Underlying conditions
Medical conditions that can cause smelly urine include:
- Kidney stones
- Kidney infection
- Bladder infection
- Chronic kidney disease
- Diabetes mellitus
- Maple syrup urine disease
- Cystinuria
When to see a doctor
It’s important to have urine that smells abnormal evaluated by a doctor. Smelly urine with a UTI can indicate:
- A complicated UTI
- Infection resistant to antibiotics
- Poorly controlled diabetes
- Kidney problems
- Rare metabolic disorder
See a doctor if smelly urine persists more than a few days after starting UTI treatment. This could mean the infection was not cured and follow-up care is needed.
Diagnosis
To diagnose the cause of foul-smelling urine, doctors may:
- Ask about your symptoms
- Perform a urinalysis
- Order urine culture
- Do imaging tests
- Test kidney function
Urinalysis
A urinalysis checks your urine for signs of infection, like:
- Nitrites
- Leukocyte esterase
- White blood cells
- Bacteria
It also looks for other causes of smelly urine like glucose, ketones, blood, and protein.
Urine culture
A urine culture can identify the specific bacteria causing a UTI. The bacteria can then be tested to find the appropriate antibiotic for treatment.
Imaging tests
Imaging studies like an ultrasound, CT scan, or MRI can check for kidney stones, tumors, kidney damage, or other problems.
Kidney function tests
Tests like a basic metabolic panel check kidney function by measuring levels of urea nitrogen, creatinine, and electrolytes in your blood.
Treatment
Treatment for smelly urine with a UTI involves:
Antibiotics
Antibiotics tailored to your infecting bacteria are used to clear UTIs. This will get rid of bacteria producing foul-smelling compounds in urine.
Hydration
Drinking more fluids dilutes urine and reduces odor. Adequate hydration also prevents dehydration that can darken and concentrate urine.
Medications
If an underlying condition like diabetes is causing the odor, your doctor may prescribe medications to treat the condition.
Diet changes
Eliminating foods that cause smelly urine in some people like asparagus, vitamin B6, caffeine, and cruciferous vegetables may help.
Prevention
You can help prevent smelly urine with UTIs by:
- Peeing after sex
- Wiping front to back
- Avoiding douches and irritating products
- Treating constipation
- Staying hydrated
- Urinating when needed
Controlling underlying medical conditions like diabetes can also prevent recurrent UTIs and smelly urine.
When to see a doctor
See your doctor if foul or abnormal smelling urine persists after UTI treatment. This could indicate:
- Another infection
- Kidney or bladder problem
- Rare metabolic disorder
See your doctor right away if smelly urine occurs with:
- Fever or chills
- Nausea and vomiting
- Back, side or abdominal pain
- Blood in urine
These can be signs of a kidney infection or other serious condition requiring prompt medical care.
Takeaways
- UTIs can cause urine to smell strong, foul, or unusual.
- Common UTI-related urine odors include ammonia, fishy, fruity, and rotten eggs.
- Smelly urine with a UTI may indicate a complicated infection or different health problem.
- See a doctor if foul-smelling urine persists after starting UTI treatment.
- Proper hydration and UTI prevention help reduce smelly urine occurrences.
| Odor | Description | Possible Cause |
|---|---|---|
| Ammonia | Pungent, like household cleaners | Bacteria breaking down urea into ammonia |
| Rotten eggs | Sulfur-like | Amino acids and volatile sulfur compounds in urine |
| Maple syrup | Sweet, like maple syrup | Maple syrup urine disease |
| Fishy | Foul, fishy odor | Bacteria producing volatile nitrogen and sulfur compounds |
| Fruity | Sweet, fruity smell | Ketones from uncontrolled diabetes |
| Popcorn | Smells like buttered popcorn | Cystinuria causing cystine buildup |
In summary, a UTI can make your urine smell foul, strong, or unusual due to bacteria, concentrated urine, diet, medications, or underlying conditions. See a doctor if smelly urine persists after UTI treatment or occurs with other concerning symptoms. With proper diagnosis and care, abnormal urine odor can be corrected and prevented.