From the Guidelines
Foul-smelling urine is most commonly caused by urinary tract infections, dehydration, and certain underlying medical conditions, and the best course of action is to increase water intake, avoid trigger foods, and seek medical attention if the odor persists or is accompanied by other symptoms. When considering the causes of foul-smelling urine, several factors come into play, including dehydration, which concentrates urine and intensifies its odor, and urinary tract infections, which can cause a distinct ammonia-like or fishy smell due to bacteria in the urinary system, often accompanied by pain, burning, and frequent urination 1. Some foods like asparagus, garlic, and coffee can temporarily alter urine odor, and medications such as antibiotics (including amoxicillin and ciprofloxacin) and vitamins (particularly B vitamins) may also affect smell. Medical conditions like diabetes, liver disease, and metabolic disorders, including organic acidemias, can cause distinctive urine odors, as identified through urine organic acid analysis 1. To address foul-smelling urine, it is essential to:
- Increase water intake to 6-8 glasses daily
- Avoid trigger foods
- Complete any prescribed antibiotics for infections
- Seek medical attention if the odor persists or is accompanied by other symptoms like pain, fever, or blood in urine. Persistent unusual urine odor, especially with other symptoms, warrants medical evaluation as it could indicate an underlying condition requiring treatment, such as asymptomatic bacteriuria, which has a high prevalence in certain populations, including diabetic patients, elderly persons, and patients with spinal cord injuries or indwelling catheters 1.
From the Research
Causes of Foul-Smelling Urine
Foul-smelling urine can be caused by various factors, including:
- Diet: certain foods and drinks can alter the odor of urine 2
- Inadequate hydration: not drinking enough water can cause urine to become more concentrated, leading to a stronger odor 2, 3
- Medications: some medications can change the smell of urine 2
- Intensive physical exercise: exercise can cause changes in urine odor due to changes in hydration status and sweat production 2
- Underlying medical conditions: certain conditions, such as urinary tract infections (UTIs), can cause foul-smelling urine 4, 5
- Bacterial infections: specific bacteria, like Aerococcus urinae, can cause malodorous urine in healthy children 4
- Dehydration: mild dehydration can increase the risk of UTIs, which can lead to foul-smelling urine 3
Bacterial Causes
Some bacterial species, such as Escherichia coli, are commonly found in recurrent lower UTIs and can cause foul-smelling urine 5. These bacteria can be resistant to certain antibiotics, making treatment more challenging.
Other Factors
Other factors, such as excessive fluid intake, can lead to water intoxication and hyponatraemia, which can cause symptoms including foul-smelling urine 6. It is essential to consider these factors when advising patients on fluid intake and treatment for UTIs.