Usually it is odorless, but it can happen that the urine has an unpleasant smell. If you do not take antibiotics – explains Dr. Alberto Saita, urologist at the Humanitas Institute – or you have not introduced foods such as asparagus, garlic, onions or cauliflowers into your diet, or the smell disappears on its own in a few hours, the foul-smelling urine could easily indicate an ongoing urinary infection.
The bad smell in the urine is given by the presence of some bacteria present in the lower urinary tract, which, in most cases, reach the bladder through the urethra, which is the small channel that allows the urine to escape. The smell, often so acrid as to seem similar to ammonia, is due to the transformation of urea, a substance always present in the urine, by bacteria (Proteus, Pseudomonas, Providencia, Morganella, and others) responsible for various infections of the urinary tract such as cystitis, urethritis, or kidney infections such as pyelonephritis. In case the bad smell of urine persists for 3-4 days, it is recommended to consult your doctor for urine culture tests (urinoculture): the report will tell you which bacteria are causing the infection and will direct the doctor towards the most effective antibiotic therapy.