Foul smelling urine is most commonly caused by urinary tract infections, dehydration and eating foods containing onions and garlic, explains Healthline. A strong urinary odor can also indicate fistulas in the bladder and kidney disease.
Odorous urine can also be a symptom of kidney stones, a condition in which chemicals in the urine become crystallized due to a combination of excess waste and minimal liquid in the kidneys, explains The National Kidney Foundation. Additional symptoms of kidney stones include back pain, stomach discomfort and bloody urine. Individuals with symptoms of kidney stones should seek immediate medical attention. Treatments for kidney stones include increased fluid intake and medications to lower acid content in the urine.