Home Symptoms Bad smelling urine: causes, treatment

Bad smelling urine: causes, treatment

by Josephine Andrews
Published: Last Updated on 225 views

Healthy urine is odorless and clear. Certain foods, but also diseases, change the chemical composition of the urine and cause those affected to perceive a different smell when going to the toilet. Read here what are the possible causes when the urine smells bad and what you can do about it!

quick overview

  • Description: Healthy urine is odorless and clear. Various causes are possible triggers for the odor of the urine to change. They are usually harmless, but in some cases, foul-smelling urine is a sign of illness.
  • Treatment: Changes in urinary odor caused by foods such as asparagus do not require treatment. If the cause is a disease, it will be treated.
  • Causes: Food such as asparagus, medication, conditions such as diabetes mellitus, ketoacidosis, cystitis, vaginal infections, congenital metabolic diseases
  • When to see a doctor?: If the urine smells abnormal for a long time, you should see a doctor as soon as possible. This is especially true if there is pain or fever. The same applies if the urine is discolored, cloudy or blood can be seen.
  • Diagnostics: urine test, if necessary further tests such as ultrasound or blood tests
  • Prevention: Since foul-smelling urine has various causes, prevention is only possible to a limited extent.

What does it mean if the urine smells bad?

Fresh, healthy urine (urine) has a neutral odor and is clear, slightly yellow in color. The decisive factor for the smell of urine is its chemical composition: it consists of 95 percent water, the rest is made up of urea, creatinine, uric acid , vitamins and salts.

In healthy people, the urine in the urinary bladder is sterile, i.e. free of pathogens. The typical strong smell of urine only occurs outside the body when bacteria convert the urea into ammonia. This means that even healthy urine begins to “stink” over time, for example if the urine has been left in a sample container for a long time or in textiles (full diapers, underwear).

Certain foods, medicines and diseases cause the composition and thus the smell of the urine to change. Most of the time, the change in smell is harmless and temporary. In other cases, however, foul-smelling urine is a sign of illness. Examples of this are urinary tract infections, ketoacidosis or congenital metabolic diseases.

What can you do about it?

How bad smelling urine is treated depends on the cause.

If foods such as asparagus or garlic are the cause of the unpleasant smell, no treatment is necessary. The odor will disappear by itself after two or three trips to the toilet, but after 24 hours at the latest. The same applies to the smell of urine that develops after taking penicillin (antibiotic): it disappears as soon as the intake is finished.

If the cause of the bad smell is a medical condition, it will be treated. Urinary tract infections and vaginal infections are mostly caused by bacteria. The doctor usually prescribes an antibiotic. In the case of a fungal infection, the doctor prescribes a so-called antifungal. Once the infection has cleared, the urine will smell normal again.

Diabetes mellitus is treated according to the specifications of the attending physician. Here it is important to keep an eye on blood sugar to avoid complications such as ketoacidosis. Ketoacidosis is severe metabolic acidosis that requires immediate hospital treatment. It is caused by a lack of insulin and occurs primarily in type 1 diabetes.

Metabolic diseases associated with urine odor are usually treated with an appropriate diet. The sooner they are diagnosed and treated, the greater the likelihood of normal physical and mental development.


Causes of strong smell of urine

Strongly concentrated urine smells “strong”. In most cases, this is caused by dehydration – the body does not get enough liquid. This is the case when those affected drink too little or lose too much liquid, for example with a fever or profuse sweating during physical exertion. To prevent the body from dehydrating further, it urinates less. The urine is darker, more concentrated than normal and smells more intense.

Morning urine may also smell more extreme. This is because the kidneys produce less urine overnight. The urine is healthy, only the amount of liquid is less than usual – the urine appears darker and smells more intensively.

Sometimes it happens that the urine of babies – while they are teething – smells more intense. The reason for this is usually that they feel unwell and therefore drink less liquid.

Causes of sweet smell in urine

Sugar in the urine causes a sweet odor. A fruity smell of urine can therefore indicate diabetes mellitus. If there is too much glucose in the blood, the body excretes the sugar in the urine.

Sweet-smelling urine is particularly common in pregnant women. In some cases, the sweet smell is a sign of gestational diabetes , but it also occurs in normal pregnancies.

Gestational diabetes is easily treatable. Be sure to have a sweet smell of urine checked out during pregnancy!

Causes of acetone-like urine smell

Acetone smells pungently sweet, similar to overripe fruit or nail polish remover. Acetone-like urine odor is an indication that there are ketone bodies in the urine (ketonuria). This is the case, for example, with ketoacidosis – a metabolic imbalance in type 1 diabetics. It indicates a severe lack of insulin.

Ketoacidosis is a medical emergency. Diabetics who notice a sharp smell of urine should call the emergency doctor immediately!

Ketone bodies are also found in urine for other reasons. They arise when the body no longer has any energy reserves (glucose) and the organism breaks down fat instead . Ketone bodies are formed as a degradation product and are excreted with the urine. This is caused by prolonged fasting or starvation. Excessive alcohol consumption also causes the body to produce more ketone bodies.

Causes of Ammonia Smell in Urine

A pungent ammonia odor in the urine is a sign of a urinary tract infection, usually caused by a bacterial bladder infection. The bacteria break down the urine, resulting in the typical sweet ammonia smell. In most cases, it is an infection with the E. coli bacteria found in the intestinal tract. They enter the urinary bladder via the urethra and cause inflammation there.

In the case of a bladder infection, not only is the smell of the urine changed, it is usually also cloudy, and in some cases bloody.

Urinary tract infections occur in women and men, but due to the shorter urethra, women are affected much more frequently. Even (small) children can get cystitis. A changed smell of urine is often the first sign here, especially in children who are not yet able to articulate their symptoms well.

Causes of sulphurous urine odor

Asparagus contains aspartic acid. In about half of all people, the sulphurous compound is broken down by an enzyme and excreted in the urine. The typical smell of sulfur forms just a few minutes after the asparagus has been eaten. In people who do not have the enzyme, the urine smells unchanged even after eating asparagus.

There are also people in whom the asparagusic acid is broken down by the enzyme, but who still cannot smell the sulphurous odor. They have a (harmless) gene mutation that prevents them from smelling sulfur. Doctors refer to this phenomenon as “selective non-smelling”.

Causes of other urine odors

In addition to asparagus, there are other foods whose smell passes into the urine. These include garlic, coffee, Brussels sprouts and salmon. The same applies to some spices, vitamin supplements and certain cereals; they can trigger a chocolatey urine odor.

Foul-smelling urine from congenital diseases

In rare cases, the urine smells strange even in newborns. The cause is usually a congenital metabolic disease.

These include:

Phenylketonuria: Phenylketonuria is a rare, congenital metabolic disease. Due to a genetic modification, the body lacks a certain enzyme (phenylalanine hydroxylase), which typically leads to so-called failure to thrive in the second to fourth month of life: mental and motor development is delayed. The affected children suffer from severe restlessness and seizures, and the urine also has a noticeable odor reminiscent of mouse droppings or horse stables.

Nowadays, every newborn in Germany and Austria is examined for various congenital diseases on the second or third day of life. This includes testing for phenylketonuria.

Phenylketonuria is easily treatable. However, those affected must adhere to a strict diet for life!

Maple syrup disease: Maple syrup disease (branched chain disease, leucinosis) is an inherited, genetically determined metabolic disorder in which certain amino acids (building blocks of proteins) cannot be broken down. These accumulate in the body and cause the typical symptoms such as poor drinking, vomiting, muscle weakness, breathing disorders and seizures. Affected children also develop a sweetish-spicy body and urine odor reminiscent of maple syrup. If the disease is diagnosed and treated at an early stage, affected children develop normally as far as possible.

Causes of putrid odor in urine

If the smell of urine is reminiscent of rotten eggs, caution is advised. The foul smell may indicate cell breakdown in the urinary tract, such as in bladder cancer.

If you smell foul urine, get yourself examined as soon as possible. The earlier a tumor is diagnosed, the better the chances of recovery!

Causes of fishy odor in urine

If the urine smells fishy, ​​there is usually an infection in the vaginal area (bacterial vaginosis). Women who are going through the menopause are often affected. The fluctuating hormone levels throw the vaginal flora out of balance, and pathogenic bacteria multiply more easily.

In very few cases it is the so-called fish smell syndrome, a mostly congenital disease in which those affected secrete a substance (trimethylamine) that smells strongly of spoiled fish. The disease occurs only very rarely, worldwide only around 200 cases of fish smell syndrome are known.

Causes of urine smelling of yeast

Urine that smells like yeast is an indication of a fungal infection. The most common cause of this is Candida. In addition to the typical smell of urine, those affected usually suffer from severe itching and whitish coatings on the genital mucosa.

When to the doctor?

If you have foul-smelling urine, you don’t always need to see a doctor. If foods such as asparagus or coffee are the reason for the changed smell, it usually disappears after two or three trips to the toilet. If the active substance penicillin is the trigger, the urine smells as long as the antibiotic is taken.

If, on the other hand, the foul-smelling urine cannot be traced back to food or medication, or if the urine smells unpleasant for a long time, it is advisable to see a doctor. This is especially true if there is pain or fever. The same applies if the urine is discolored, cloudy or reddish (bloody).

Examination/What does the doctor do?

The first point of contact for foul-smelling urine is your family doctor or urologist. He asks about the current symptoms, how long they have existed and whether there are any other symptoms apart from the changed smell of urine. He then examines the patient and gets an initial picture of his physical health.

The central point of the diagnosis is a urine test. The patient provides a urine sample in a sterile container. To ensure that as few skin germs as possible get into the sample, it is important to note the following:

  • First wash your hands.
  • Men retract the foreskin.
  • Women spread their labia with their fingers.
  • Now let a little urine into the toilet, only then collect the middle portion of the urine (mid-stream urine) in the cup.
  • Be careful not to touch the inside of the cup with your fingers or genitals.
  • Seal the cup.

The doctor then examines the urine for changes. Deviations in the smell and color of the urine give the doctor the first indications of possible causes. If the urine smells like ammonia and is cloudy, this is a sign of a urinary tract infection. A sweet smell of urine indicates diabetes mellitus.

In the next step, the doctor dips a urine test strip into the sample ( urine test ) and checks whether there are components in the urine that do not belong there, such as ketone bodies, proteins , glucose (sugar) or blood.

The doctor then analyzes the urine under a microscope. Red and white blood cells, tissue cells, crystals, bacteria and parasites can be identified and assessed.

If there is a suspicion of a bacterial infection, the doctor creates a so-called urine culture. This is a plastic dish (agar plate) with a kind of jelly on which the bacteria grow particularly well. This allows the doctor to identify the type of pathogen. This is important in order to be able to specifically treat the infection with an antibiotic.

Sometimes an ultrasound scan is necessary. The doctor pays attention to changes in the urinary tract that are not visible from the outside, such as constrictions, foreign bodies or tumors.

It is also possible to measure the urine concentration. The patient collects his urine in a container for 24 hours. This allows conclusions to be drawn about the filter performance of the kidneys.

After the urine test is complete, the doctor is able to further isolate and treat the cause of the urine odor. If, for example, there is a bladder infection, the patient is given a suitable antibiotic. If glucose or ketone bodies are present in the urine, the doctor will do other tests, such as a blood test. If a genetic disease is suspected, a molecular genetic examination follows. Patients suspected of having a tumor in the area of ​​the urinary tract are usually referred by the doctor to an oncologist.


Urine odor caused by food is harmless and disappears on its own within a few hours. The only way to prevent it is to avoid the relevant triggers, such as asparagus, garlic or coffee.

Congenital diseases such as phenylketonuria or maple syrup disease have no means of prevention.

In diabetics, it is important to prevent ketoacidosis. It not only causes an acetone-like smell in urine, but is life-threatening if left untreated. Talk to your doctor about ways to prevent severe insulin deficiency.

You may also like

Leave a Comment