Why does my urine smell sour

Urine smell

The following smells in the urine should always be taken into account:

  • alcoholic urine smell
  • fish-like urine odor
  • sweetish urine smell (of fruit)
  • Sharp, acrid urine smell of ammonia
  • putrid urine smell

The causes of the smells can be divided into causes

Urinary tract infection

If you have a urinary tract infection or a bladder infection, urine can smell strong and sometimes fishy. Urinary tract or bladder infections tend to be more common in women. Bacteria that have penetrated the urine break down the urine, making it smell stronger. In addition to bacteria, viruses or fungi can also trigger an infection.


If the urine has a fruity odor, this can be a sign of a metabolic imbalance in the context of diabetes. Odor is caused by what is known as ketoacidosis, which indicates a severe lack of insulin.


Best known is the strong urine odor after consuming asparagus. Foods like garlic, cabbage, coffee, or alcohol can also cause an unusual urine odor. This is usually harmless and the smell evaporates again after the relevant substances have been excreted.


Urine consists of 95 percent water and about 5% of the filtrates and other components. If the ratio of these ingredients is disturbed, the color and smell change. If the urine is intensely colored and has a strong smell of ammonia, this can indicate dehydration. In this case, the amount of water in the urine is lower and the urine is more concentrated. The darker the urine, the stronger its odor is often. Other signs of dehydration are low blood pressure and overheating.


Drugs such as penicillin also affect the smell of urine. Some patients report that the odor is unpleasantly smelly.


Tumors in the urinary tract, bladder, or kidneys can cause a foul odor in the urine. The smell arises mainly by cell disintegration.

If the urine smells extremely unpleasant, this is definitely an alarm signal and should be clarified immediately.

Other symptoms include blood in the urine, constant need to urinate, and a feeling of inflammation of the bladder.


Phenylketonuria is a congenital metabolic disease in which the enzyme phenylalanine hydroxilase, which is produced in the liver, is defective.

Symptomatic of this disease is that the urine smells like mouse droppings or horse stables. A quick diagnosis after birth and subsequent dietary treatment can ensure healthy development. Phenylketonuria is usually not determined by the urine but by the Guthrie test or tandem mass spectrometry after birth.

Maple syrup disease

Today, as with phenylketonuria, the diagnosis of maple syrup disease is made in the extended newborn screening program using tandem mass spectrometry shortly after birth. With maple syrup, the urine smells sweet and spicy and is reminiscent of maple syrup - which is where the name comes from. The disease causes a disturbed metabolism of the amino acids, which if left untreated can have very serious consequences.

See also: urinary tract infection, bacteria in the urine, blood in the urine