Smelly urine or urine that has an unusual odor may be a result of diabetes, an infection, eating asparagus, or using certain medications, among other causes. Treatment can depend on the underlying cause.

Urine often has a slight ammonia smell, especially first thing in the morning or when a person is dehydrated.

However, smelly urine can also be a sign of an infection. If the smell does not go away on its own or additional symptoms develop, it is best to contact a doctor.

This article explores what causes smelly urine and offers strategies to help reduce the smell.

Smelly urine does not always stem from a health condition. Dehydration, some vitamins, and certain medications can give urine an unpleasant odor.

Common causes of smelly urine include:

Concentrated urine

When urine is highly concentrated, it contains more ammonia and less water. This can cause it to have a strong smell.

Urine tends to be more concentrated when a person is dehydrated. This is often the case first thing in the morning or when someone does not drink enough water throughout the day.

Symptoms of severe dehydration include:

If dehydration symptoms do not go away after a person drinks plenty of water, it is best to contact a doctor. The underlying issue may be a kidney infection.


Metabolites are any substances that form during digestion. As the body excretes metabolites in urine, some can cause the urine to smell.

For example, when asparagus breaks down during digestion, its metabolites give urine a foul smell.

Medication and supplements

Some medications and supplements that can lead to a change in the odor of urine include:

Some health issues that lead to smelly urine require short courses of treatment, while others require more lasting attention.

Urinary tract infection

A urinary tract infection (UTI) happens when harmful bacteria proliferate in the urethra, bladder, or kidneys.

Most people have symptoms beyond smelly urine, including:

A UTI usually clears up with antibiotics. If a person does not receive treatment, the infection can spread, so it is best to contact a doctor as soon as possible.

Bacterial vaginosis

The vaginal infection bacterial vaginosis causes a distinct fishy odor that may be worse after sex. Other symptoms include:

  • pain
  • itching
  • burning pain while urinating
  • thin, white or gray discharge

Learn about treating bacterial vaginosis at home.


Diabetes medications may change the smell of urine, and so too can the disease — especially if blood sugar levels go uncontrolled.

Some people notice a very sweet smell. This happens when there is too much sugar in the urine.

Other symptoms of diabetes include:

Some people find that asparagus gives their urine a strong, foul odor that may last from a few hours to a few days.

Some people may not be able to detect the odor. Research from 2016 suggests that about 60% of people have one of several genetic variants that either decrease their ability to smell asparagus in urine or eliminate it entirely.

Some people notice a change in the smell of their urine during pregnancy. Various hormonal changes may change the smell of urine — or the person’s sensitivity to smells.

According to a 2022 review of studies, as many as two-thirds of healthy women report a stronger sense of smell during pregnancy. This may mean a pregnant person can smell their urine more intensely.

However, urine with a strong odor could signify a UTI. A person concerned about their urine smell may wish to contact a doctor.

Prompt treatment of UTIs decreases the risk of serious complications for the person and the fetus.

To reduce the smell of urine, a person may try:

  • avoiding eating foods that cause urine to smell, especially asparagus
  • switching supplements if high levels of thiamin or choline are likely culprits
  • drinking plenty of water to support hydration and kidney and urinary tract health
  • visiting the bathroom as soon as the urge strikes
  • managing any chronic medical conditions, such as diabetes, as carefully as possible, with the guidance of a doctor

Also, having an overall healthy lifestyle and reducing or eliminating alcohol intake can protect the liver and may help get rid of the smell.

The doctor will ask about certain lifestyle factors, recent health changes, and when the bad smell began. They may do a urine culture to check for bacteria and other signs of infection.

When the diet is responsible for the smell, the doctor may be able to determine the cause based on symptoms alone.

In some cases, the doctor may order imaging scans of the urinary tract or kidneys. A person may also need blood work to check for other health conditions.

A bad smell in the urine often goes away on its own, especially when it results from dehydration or something in the diet.

A person does not need to speak with a doctor if they can identify a harmless cause of their smelly urine, such as asparagus.

Other causes need medical treatment. While a UTI is relatively harmless, it can progress and cause serious health issues, including kidney infections. With early treatment, a person should feel better in a few days.

Because some people with UTIs have no symptoms, it is best to speak with a doctor if the bad smell lasts longer than a few days. This is especially important for people who are pregnant.

Other health issues that can cause this odor require ongoing treatment. For example, a person with diabetes may need to switch medications or make certain lifestyle changes.

If a person with a chronic condition finds that the smell of their urine changes significantly, it may be a good idea to flag it with a doctor.

Foul-smelling urine can be alarming, but it may be short-lived, and drinking more water may help the smell fade faster.

However, if there is no clear cause — such as asparagus, supplements, or dehydration — it is a good idea to consult a healthcare professional.