Some possible causes of foul-smelling urine are a urinary tract infection, cystitis, the ingestion of certain foods, dehydration and kidney stones. When there is bacteria present in urine due to an infection, urine also tends to be cloudy in appearance in addition to having a foul smell, states MedicineNet. Medical conditions like a urinary tract infection and cystitis are caused by a bacterial infection.
Asparagus can also cause urine to smell strong and unpleasant. Similarly, medications, vitamins and dehydration can cause changes in the way urine smells, notes Mayo Clinic. For example, a person who is severely dehydrated can have urine that has a very strong ammonia odor.
Kidney stones are another medical problem that can cause malodorous urine, according to the National Kidney Foundation. This condition can also cause urine to appear cloudy, and blood may be present in the urine as well. Kidney stones form from chemical waste found in urine. These stones can remain in the kidneys or move to other areas, such as the ureter. While small stones may be eliminated in urine when it leaves the body, larger stones are more difficult to eliminate. Besides bad smelling urine, stones can produce pain and fever.
Urine usually has no strong odors if its water content is high. When there is a decrease in the volume of water and an increase in the amount of waste in the urine, it can lead to strong smelling urine.