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What Causes Bad-Smelling Urine? Learn Why This Occurs & What to Do

Urine could have foul, strong, or sweet smelling characteristics. The most common causes of bad smelling urine are dehydration, dietary changes, or a side-effect of medication. Less commonly, strong smelling urine can also be caused by infection, high blood sugar, or liver damage. Read below for more information on associated symptoms, other causes and foods that make your urine smell, and treatment options.

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Common Urine Odor Symptoms

Urine is meant to have a mild odor. If you are well-hydrated, it may not smell like anything, or it may take on the aroma of something you ate or drank, like asparagus or coffee. If your urine smells, the odor should be relatively mild. A strongly disagreeable smell can be a sign of illness [1].

Common characteristics of bad-smelling urine are

If you're experiencing bad-smelling urine, it can likely be described by:

  • An ammonia smell
  • An overly sweet, almost sugary smell
  • A musty smell
  • A foul smell
  • A sulfurous smell

Duration of bad-smelling urine

Depending on the cause, your bad-smelling urine may be more temporary or more persistent.

  • Temporary: A bout of bad or foul-smelling urine will resolve quickly if it was simply caused by foods or drinks.
  • It may last days if due to an infection
  • Persistent: Conditions like diabetes or liver failure may last weeks or months if not treated.

Who is most often affected by bad or foul-smelling urine

The following people are more likely to experience bad-smelling urine.

  • Diet and medication habits: Anyone who eats certain foods (like asparagus) or takes certain supplements (like vitamin B6) or medications can be affected.
  • Sexually active and older women: UTIs are more likely among these women and they are often affected [2].
  • Anyone with diabetes or liver or kidney failure

When is bad-smelling urine most likely to occur

Bad-smelling urine is more likely at these times or environments:

  • In the morning: It is not uncommon for urine to smell stronger in the morning, because it will be more concentrated after you've gone several hours without drinking anything.
  • In hot weather: Being outside in hot weather can cause some dehydration through sweating, with the same result.

Is bad or foul-smelling urine serious?

The severity of your bad-smelling urine is ultimately dependent on the cause.

  • Not serious: Any changes in urine smell are most often temporary and can be connected with becoming dehydrated, eating certain foods, or starting a new supplement or medication. If you have no other symptoms, it's rarely a concern.
  • Moderately serious: If there is also an unusual color to the urine, along with a persistent and very disagreeable odor, you may have a condition that should be treated.
  • Serious: If you have the above signs along with pain or other symptoms of illness, you should see your medical provider as soon as possible.

Why Your Urine Smells

Many conditions can have bad or foul-smelling urine as a symptom. The most common are those involving dehydration, eating certain foods, taking certain medications or supplements, and urinary tract infections.


Dehydration can be caused by more than just not drinking enough water [1,3].

  • Poor hydration: Simply not drinking enough water causes the urine to become dark and concentrated and have a bad odor.
  • Drinking alcohol: This causes dehydration — the same dehydration responsible for the headache that comes with a hangover.
  • Medication: Some medications and supplements cause increased urination. Diuretics are meant to rid the body of excess fluid but can leave you somewhat dehydrated.
  • Heavy exercise with sweating: This can also lead to dehydration.

Food, supplements, and medication causes

Causes of bad-smelling urine can be due to certain foods or medications you take.

  • Asparagus: This is a well-known offender when it comes to causing a strong smell to the urine, due to its high sulfur content [1].
  • Garlic, onions, leafy vegetables, and eggs: These also all contain sulfur too, but like asparagus they are good for you and there is no need to avoid them. Any smell they give to the urine is harmless [1,2].
  • Vitamin B6: Also called pyridoxine, may cause a strong smell to the urine in doses of more than 10 mg per day.

Medical causes

Bad-smelling urine may occur due to certain medical causes, such as the following.

  • Bacterial infection: Inflammation of any part of the urinary tract tends to cause a foul smell to the urine [4].
  • High blood sugar: This causes a strong sweet smell to the urine [5].
  • Liver damage: This causes a sweetish, musty smell to both the breath and the urine, because toxins are not being properly filtered out of the blood [1].

2 Possible Bad Smelling Urine Conditions

The list below shows results from the use of our quiz by Buoy users who experienced bad smelling urine. This list does not constitute medical advice and may not accurately represent what you have.

Urinary tract infection

A urinary tract infection is an infection of the urinary tract, which includes the kidneys, bladder, and urethra. Urinary tract infections are usually caused by infections by fecal bacteria.

Symptoms of urinary tract infections include pain with urination (dysuria), ...

Bad Smelling Urine Symptom Checker

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Non-specific change in urine

Urine is the product of the kidneys filtering the blood from waste products and excess water. Depending on what you eat, the color and odor of your urine can change. Beets are known to turn urine pink or red, which can be mistaken for blood. Asparagus sometimes gives a distinctive smell. Medication can also change smell and color of your urine.

Rarity: Common

Top Symptoms: a change in either color of odor of urine, frequent urination

Symptoms that always occur with non-specific change in urine: a change in either color of odor of urine

Symptoms that never occur with non-specific change in urine: painful urination, bright red (bloody) urine, fever, frequent urination

Urgency: Wait and watch

When and How to Treat Smelly Urine

When it is an emergency

Seek immediate treatment for foul-smelling urine in the emergency room or call 911 if:

  • You have extreme fatigue, ongoing thirst, and increased urination: Along with a strangely sweet smell to the urine
  • You have back pain: Along with chills, fever, and foul-smelling urine that looks pink or red
  • You have ongoing fatigue with yellowing of the skin and eyes (jaundice): Along with swollen ankles, and a musty smell to the urine and breath [6,7]

When to see a doctor

Schedule an appointment if:

  • You are on a diuretic medication and have bad-smelling urine: Your medical provider may be able to change or adjust the dosage of the diuretic.
  • You have lower abdominal pain with foul-smelling urine
  • You have foul-smelling urine and urinary urgency or frequency

At-home treatment

Remedies that you can try at home for bad-smelling urine include the following:

  • Drink more water on a regular basis
  • Take vitamin C tablets [8]
  • Drink green tea [8]
  • Drink unsweetened cranberry juice or take over-the-counter cranberry concentrate tablets: Do not use cranberry products if you've had a kidney stone or you are taking a blood thinning medication (an anticoagulant) [9].

FAQs About Bad Smelling Urine

Here are some frequently asked questions about bad smelling urine.

Can bad smelling urine be a STD?

Yes, foul-smelling urine can be caused by an STD also known as a sexually transmitted infection (STI). Sexually transmitted infections and bladder infections can change the smell of urine. One type of sexually transmitted infection, known as trichomonas, can lend a fishy odor to vaginal discharge. A urinary tract infection (UTI) can cause pus within the urine and may also cause pungent and foul-smelling urine this is usually the primary cause. Foods can also change the smell of urine. This includes coffee or asparagus, as consumption can lead to changes in the smell of urine. Because "bad" smelling urine is subjective, it can be mistaken for infections [10].

Can pregnancy cause bad smelling urine?

Yes. Pregnancy can increase the chances of a bladder infection because the gravid (pregnant) uterus can change the ability of the bladder to empty sufficiently. The bladder with urine in it for a long time can allow bacteria to grow and produce foul-smelling urine. If this happens, it should be treated immediately [11].

Does bad smelling urine mean infection?

Foul-smelling urine can come from many sources. Most commonly, bladder infection. If you have a sudden change in the smell of your urine, you may be experiencing this due to the consumption of certain foods or vitamins (e.g. B vitamins, asparagus). However, a change in the smell of urine (or the appearance) is a hint that you may have a bladder infection. This can be caused by improper hygiene, catheterizations, kidney stones or anything that keeps you from completely voiding your bladder [11,12].

Is foul smelling urine a sign of dehydration?

Dehydration may increase the concentration of one's urine. Urine is also often darker. Foul-smelling urine is different from a change in the intensity of the smell of urine. The quality of the smell is also different from simply being stronger, and the color may change from yellow to orange or cloudy or red. These may be signs of a urinary tract infection (UTI) or a sexually transmitted infection (STI) and require medical attention [13].

What causes bad smelling urine with no other symptoms?

Eating foods that are partially excreted via the urinary tract can change the smell of urine and cause "bad-smelling urine." Foods like asparagus are commonly associated with bad-smelling urine and is a genetic predispostion. Usually, foul-smelling urine is associated with infections and can happen in the absence of other symptoms. It may also be accompanied by bladder pain and possibly fever/chills in most cases. Dehydration and concentration of urine can also increase the intensity of the smell of urine.

Questions Your Doctor May Ask About Bad Smelling Urine

To diagnose this condition, your doctor would likely ask the following questions:

  • Do you feel pain when you urinate?
  • Have you noticed any changes in the color of your urine recently?
  • Any fever today or during the last week?
  • Have you ever had a urinary tract infection?

The above questions are also covered by our A.I. Health Assistant.

If you've answered yes to one or more of these questions

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Bad Smelling Urine Symptom Checker Statistics

People who have experienced bad smelling urine have also experienced:

  • 8% Vaginal Discharge
  • 6% Painful Urination
  • 5% Vaginal Itch Or Burning

People who have experienced bad smelling urine were most often matched with:

  • 100% Urinary Tract Infection

Source: Aggregated and anonymized results from visits to the Buoy AI health assistant (check it out by clicking on “Take Quiz”).

Bad Smelling Urine Symptom Checker

Take a quiz to find out what might be causing your bad smelling urine


  1. Smelly Urine. NHS. Published October 16, 2017. NHS Link
  2. Lowe M. NHS: University Hospitals Birmingham. Published December 2017. UHB Link
  3. Dehydration. NHS. Published February 6, 2017. NHS Link
  4. Urinary Tract Infections (UTIs). NHS. Published December 12, 2017. NHS Link
  5. Husney A, Thompson EG, Gabica MJ. Urine Test. Healthwise. Published October 9, 2017. Healthwise Link
  6. Chronic Kidney Disease Symptoms. National Kidney Center. NKC Link
  7. Common Characteristics of Liver Disease. John Hopkins Medicine. John Hopkins Medicine Link
  8. Jackson CB, Taubenberger SP, Botelho E, Journel J, Tennstedt SL. Complementary and Alternative Therapies for Urinary Symptoms: Use in a Diverse Population Sample Qualitative Study. Urologic Nursing Journal. 2012;32(3):149-157. PubMed Link
  9. Thompson EG, Selfert AL. Cranberry Juice and Urinary Tract Infections. American College of Cardiology: CardioSmart. Published May 16, 2011. CardioSmart Link
  10. Trichomoniasis - CDC Fact Sheet. Centers for Disease Control and Prevention. CDC Link
  11. Urinary Tract Infection During Pregnancy. American Pregnancy Association. Published March 10, 2017. American Pregnancy Association Link
  12. What Can Cause a Urine Tract Infection? Alzheimer's Society. Alzheimer's Society Link
  13. What STDs Cause Frequent Urination? STD.GOV. Published May 10, 2018. STD.GOV Link

Disclaimer: The article does not replace an evaluation by a physician. Information on this page is provided as an information resource only, and is not to be used or relied on for any diagnostic or treatment purposes.