Urine is generally clear pale yellow in color with a characteristic odor that is caused by the presence of urea , it can be very soft when it contains a large amount of water, but if it is concentrated, that is, with high levels of waste eliminated by the kidneys little water, it may have a strong odor.

If you notice that your urine occasionally has a stronger smell than normal it should not always be a cause for concern, however, you should know that there are medical problems that cause a bad smell in the urine and require medical attention.

Causes of bad smell in urine

Did you know that your urine can reveal information about your health status? In this article I am going to explain the main causes that can cause bad smell in urine .


You may have realized that eating certain foods can make your skin, breath, and even urine smell bad.

In a study published in the journal Perspectives in Biology and Medicine, they reported that asparagus can sometimes cause a bad smell in the urine (similar to decomposing cola) and change the typical yellow color to a greenish tone, due to the fact that they contain asparaguzic acid, which although not It is toxic and is responsible for causing the bad smell in the urine after consuming asparagus.

But not only asparagus have this effect, some foods such as garlic or cauliflower can also alter the smell of urine. Besides coffee, alcohol and tea, which act as diuretics, therefore, your urine will become more concentrated and this will also cause a strong smell.

Certain medications and vitamins

If you are taking antibiotics from the family of penicillins and sulfonamides, or formulas with vitamin B or C complex, they could be the cause of bad smell in the urine and color changes .

Supplements combined with vitamin B have the side effect of causing orange or greenish-yellow urine, vitamin B6 could cause an unusual smell in the urine (1) in some people. Even consuming foods rich in B vitamins in excess can alter the normal characteristics of your urine.


If you don’t drink enough fluids and you are dehydrated, you may notice changes in the smell and color of your urine. The smell of urea will be more intense since the urine is little diluted .

It is common for the first urine in the morning to have a stronger smell, but in the course of the day when we drink more water it improves.

If you are dehydrated you should drink more fluids, up to 3 liters of water daily is recommended so that it returns to normal and the urine becomes almost transparent and odorless. If you have other symptoms such as weakness, drowsiness or mental confusion, it could be a more serious clinical picture of dehydration and you should see a doctor immediately.

Urinary infections

Urinary tract infections are caused by bacteria in the urine and are accompanied by other symptoms such as a burning sensation and a constant urge to urinate. It is more common in women and older adults who cannot completely empty their bladder.

The normal thing is that your urine is sterile (free of microorganisms), when a bacterium colonizes around the urethra, it can ascend towards the urinary tract causing the infection, the bacteria transform urea into ammonia , a substance that causes the bad smell in the urine .

Treatment is with antibiotics, high fluid intake, and a healthy habit of urinating five to seven times a day.


In people with diabetes who have high blood sugar, the urine takes on a sweet smell.

Although in general they also present other symptoms such as weight loss, constant thirst, the need to eat and an increase in the amount of urine eliminated. If you have any of these symptoms, you should receive medical attention to start treatment.


Phenylketonuria is a genetic disease, in which there is accumulation of the amino acid phenylalanine, due to a defect in the gene for the enzyme necessary to break it down, causing a deficiency or lack of it, it can be mild, moderate or severe.

Symptoms include foul odor in urine, breath, and skin (similar to moisture) due to excess phenylalanine in the body. Neurological problems, skin rashes, among others, are also associated.

Newborns at the beginning do not present symptoms, but without adequate treatment in a few months they will begin to have them.

The main treatment (2) includes a diet of limited life in proteins, since these contain phenylalanine.

Maple syrup disease

It is a genetic and incurable disease (3) characterized by the accumulation of amino acids such as leucine, isoleucine and valine. It is caused by a defect in the genes that prevents people with the disease from metabolizing these amino acids.

The name of the disease is due to the fact that the urine has a characteristic smell of maple syrup . Treatment is based on eliminating toxic substances through dialysis and other techniques, apart from providing nutritional support.

The bad smell of urine can be caused by many reasons, some can be easily solved, just by increasing your water intake or modifying your diet and in 12 hours the bad smell can disappear, however, if it persists, you should consult with your trusted doctor to rule out other diseases.

By Dr. Eric Jackson

Dr. Eric Jackson provides primary Internal Medicine care for men and women and treats patients with bone and mineral diseases, diabetes, heart conditions, and other chronic illnesses.He is a Washington University Bone Health Program physician and is a certified Bone Densitometrist. Dr. Avery is consistently recognized in "The Best Doctors in America" list.

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