Smelly Urine: Why Urine Smells Strong, Sweet or Fishy and Which Tests Check It

Most smelly urine comes from concentrated urine, something you ate or a supplement or medicine. A foul smell with burning or urgency can mean a urinary tract infection, and a sweet or fruity smell can point to high blood sugar or ketones. Learn which smell maps to which urinalysis line or blood test, what an all-normal urinalysis means, and when to get prompt care.

Published: November 9, 2026
Read time: 13 min read
Medically reviewed by: Rhonda Collins, FNP-C

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Most smelly urine comes from urine that is more concentrated than usual, from something you ate or drank, or from a medicine or vitamin. These changes usually go away on their own ^[1]^[2]. A strong, ammonia-like smell most often means concentrated urine. A foul smell can come from bacteria, as in a urinary tract infection (UTI). A sweet or fruity smell can be a sign of uncontrolled diabetes or high ketones ^[1]^[3].

A urinalysis is the test that separates these causes. Specific gravity shows how concentrated the urine is. Nitrite and leukocyte esterase point to infection, and a urine culture confirms it. Glucose and ketones check the sweet-smell causes, and a hemoglobin A1C blood test follows up on blood sugar ^[1]^[3]. The sections below go through each smell and the test that checks it.

What normal urine smells like

Healthy urine usually does not have a strong smell, especially when you drink plenty of fluids ^[1]. Normal urine is usually clear or pale yellow with a mild smell ^[2]. Clinicians describe the normal odor as “urinoid,” and it can get stronger in a concentrated sample without meaning an infection ^[3].

Urine odor varies from day to day. Most changes are not a sign of disease and go away in time ^[1]. A new smell matters more when it lasts after you are drinking normally, or comes with other symptoms such as burning, fever or a change in color.

Why urine smells strong or like ammonia

Urine that smells strong or like ammonia is most often concentrated, because your body is low on fluids ^[1]. MedlinePlus lists concentrated urine smelling like ammonia among the causes of a change in urine odor ^[1]. A review of urinalysis for family physicians notes that a strong odor may come from a concentrated sample rather than a UTI ^[3]. Urine that sits in the bladder for a long time can also develop an ammonia smell ^[3].

On a urinalysis, concentration shows up as specific gravity, a measure of how many particles are dissolved in the urine ^[4]. The normal range is 1.005 to 1.030 ^[4]. Dehydration is one of the causes of a high result, and glucose in the urine can also raise it ^[4]. A strong smell with a high specific gravity and no other abnormal line fits concentrated urine.

The usual fix is more fluid. If the smell goes away once you drink more, concentration was the likely cause. For what concentration does to urine color, see dark urine.

Foul or fishy-smelling urine and UTIs

A foul smell can come from bacteria in the urine, and strong-smelling urine is one of the listed symptoms of a bladder infection ^[1]^[5]. Other bladder infection symptoms include burning when you urinate, frequent or intense urges to urinate, pain or discomfort in the lower belly, and cloudy or bloody urine ^[5]. A pungent smell is common in people with a UTI ^[3], but the smell alone does not confirm one.

Three tests check for infection:

Nitrite. Many bacteria that cause UTIs turn nitrates in urine into nitrites, so a positive nitrite result may mean a UTI. Some bacteria do not, so a negative result does not rule one out ^[6]. For more, see nitrites in urine.
Leukocyte esterase. This dipstick line is produced by white blood cells and may signal the white cells in urine that go with a UTI ^[3]. See white blood cells in urine.
Urine culture. A culture grows bacteria from the sample to show which ones are present and which antibiotic is likely to work ^[7]^[8]. The microscopic exam also counts bacteria directly.

A urinalysis can diagnose an infection most of the time, and a culture identifies the bacteria ^[7]. If the smell comes with cloudiness, see cloudy urine. If it comes with needing to go more often, see frequent urination.

A fishy smell is not tied to one cause in the medical sources this article uses. Treat it like any foul smell: with UTI symptoms, test for infection; without them, think about food, fluids and supplements first. A rare inherited cause is covered under rare metabolic conditions.

Sweet or fruity-smelling urine

Sweet-smelling urine may be a sign of uncontrolled diabetes, and diabetic ketoacidosis can make urine smell fruity or sweet ^[1]^[3]. Two lines on a urinalysis check these causes: glucose and ketones.

Glucose. Urine normally contains little or no glucose, because the kidneys send it back to the blood ^[9]. Diabetes is the most common cause of high urine glucose ^[9]. A normal result does not rule out diabetes, because urine glucose can be normal when blood glucose is high ^[9]. Because urine glucose testing is less accurate, blood tests are now more commonly used to diagnose diabetes ^[9].

Ketones. When cells cannot get enough glucose, the body breaks down fat for energy, which makes ketones ^[10]. Some ketones in urine are normal. High levels can come with diabetes, long-lasting vomiting or diarrhea, alcohol use disorder, a very low-carbohydrate “keto” diet, starvation or very long, hard exercise ^[10]. In diabetes, high ketones can mean diabetic ketoacidosis, a medical emergency that can develop quickly ^[10].

The blood test that follows: hemoglobin A1C. A1C shows your average blood glucose over the past two to three months ^[11]. An A1C below 5.7% is normal, 5.7% to 6.4% is prediabetes, and 6.5% or higher is diabetes, and more than one test is often used to confirm a diagnosis ^[11]. A hemoglobin A1C test can be ordered on its own.

Pregnancy is one of the situations in which glucose or ketones can show up in urine ^[9]^[10].

Foods and drinks that change urine smell

Some foods change urine odor, and asparagus is the best-known example ^[1]. Asparagus gives urine a sulfurous smell similar to cooked cabbage ^[12]. Not everyone notices it. In a study of 6,909 adults of European-American descent, 58.0% of men and 61.5% of women did not report a strong smell after eating asparagus, and the ability to smell it was linked to genetic variation near smell-receptor genes ^[13]. People also differ in whether their bodies produce the smell at all ^[12].

Coffee and garlic can also make urine smell stronger, and garlic and asparagus contain strong-smelling chemicals that pass into urine ^[2]. Like most changes in urine odor, these go away in time ^[1].

Supplements and medicines

Some medicines and vitamin supplements can change how urine smells ^[1]^[2]. The NHS names vitamin B6 supplements as one example ^[2]. A smell that starts soon after a new medicine or supplement is likely related to it.

Do not stop a prescribed medicine because of a smell. Ask your pharmacist or prescriber whether it explains the change. A smell that does not fit anything you ate or took, and does not go away, is the one to get checked.

Other urine smells: sulfur, musty and fecal

A sulfur smell is the usual description of urine after eating asparagus ^[12]. A sulfur-like smell can also come from the breakdown of cystine, an amino acid ^[3].

A musty smell can come from liver disease and certain metabolic disorders ^[1].

A fecal smell can come from a fistula, an abnormal connection between the bowel and the bladder ^[1]^[3]. This is uncommon.

A popcorn-like smell is a common search, but we found no primary medical source that links it to a specific cause. Treat it like any new smell: check fluids, food and supplements first, and test if it lasts or comes with symptoms.

Does smelly urine mean kidney disease?

A change in urine smell is not among the symptoms of chronic kidney disease listed by the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) ^[14]. Most people with early chronic kidney disease (CKD) have no symptoms. For many people, the only way to know is to have blood and urine tests ^[14]. The urine changes listed for advanced CKD are foamy urine and a change in how often you urinate ^[14]. See foamy urine.

The tests that check kidney function are:

Creatinine and eGFR. Creatinine is a waste product from normal muscle breakdown, and its level in the blood is used to estimate the glomerular filtration rate (GFR). A GFR of 60 or more is in the normal range, less than 60 may mean kidney disease, and 15 or less is called kidney failure ^[15]. A comprehensive metabolic panel includes creatinine and eGFR.
Urine albumin. A healthy kidney does not let albumin into the urine. A urine albumin-to-creatinine ratio of 30 mg/g or less is normal, and more than 30 mg/g may be a sign of kidney disease ^[15].

For which symptoms point to the kidneys, see kidney disease symptoms and blood tests.

Rare metabolic conditions

A few rare inherited conditions change urine odor, including metabolic diseases that can make urine smell sweet and trimethylaminuria, which causes a strong fishy odor in sweat, urine and breath ^[1]^[16].

Which tests check a urine smell

A urinalysis is the first test for a smell that lasts or comes with symptoms, and MedlinePlus lists it with a urine culture as the tests to expect ^[1]. Each smell maps to specific lines:

Smell	Urinalysis lines to look at	Blood test that may follow
Strong or ammonia-like	Specific gravity for concentration ^[4]	None if everything else is normal
Foul, pungent or fishy	Nitrite, leukocyte esterase and bacteria, then a urine culture ^[3]^[6]^[8]	Usually none
Sweet or fruity	Glucose and ketones ^[9]^[10]	Hemoglobin A1C or blood glucose ^[9]^[11]
Kidney concern	Protein on the dipstick, or a urine albumin-to-creatinine ratio ^[15]	Creatinine and eGFR ^[15]

Mito offers several ways to run these:

The Urinalysis, Complete Test with Reflex to Urine Culture reports color, specific gravity, nitrite, leukocyte esterase, glucose, ketones and protein, plus a microscopic count of white blood cells and bacteria. If the urinalysis shows signs of a possible infection, a urine culture runs automatically.
The Urinalysis, Routine Test reports the dipstick lines, including specific gravity, nitrite, leukocyte esterase, glucose and ketones.
A Urine Culture, Routine Test can be ordered on its own when infection is the main question.

How to read a urinalysis for a urine smell

On a normal urinalysis, glucose, ketones, protein and bilirubin are usually not detectable, and nitrites, white blood cells, red blood cells and hemoglobin are not normally found ^[17]. Specific gravity falls between 1.005 and 1.030 ^[4]. Reference ranges vary slightly between labs ^[17].

Read the lines together:

High specific gravity, everything else negative: concentrated urine ^[3]^[4].
Nitrite or leukocyte esterase positive, with bacteria or white blood cells: a possible UTI. A culture confirms it ^[6]^[7].
Glucose positive: possible high blood sugar. A blood test, such as A1C, is the next step ^[9]^[11].
Ketones positive: the body is burning fat for energy. With diabetes and symptoms such as vomiting, belly pain or confusion, this is urgent ^[10].

What an all-normal urinalysis means

An all-normal urinalysis points away from infection, high urine glucose and high ketones at the time of the sample, which leaves food, fluids, supplements and medicines as the likely causes of the smell ^[1]^[17]. It has limits. A negative nitrite does not rule out a UTI, because some bacteria do not make nitrite ^[6]. A normal urine glucose does not rule out diabetes, because urine glucose can be normal when blood glucose is high ^[9]. The sample is most reliable when examined within two hours of collection ^[3].

If the smell goes on and the urinalysis is normal, look for patterns: does it follow certain foods, coffee, a new supplement or low fluid days? If you also have symptoms of diabetes, an A1C test checks blood sugar directly ^[11]. For other things a urinalysis can show, see crystals in urine and mucus in urine.

How to make urine smell less

Drinking enough fluid is the main fix for smelly urine that comes from concentration ^[1]^[2]. The NHS advises ^[2]:

drinking plenty of fluids, particularly water, so you pee regularly during the day and do not feel thirsty;
drinking more in hot weather and when exercising;
not drinking a lot of sugary fizzy drinks, coffee or alcohol;
not eating a lot of garlic or asparagus.

There is no need for special drinks or cleanses. If the smell comes from an infection or high blood sugar, more water will not fix the cause, so test instead.

When to get prompt care for smelly urine

Contact your provider if abnormal urine odor comes with signs of a urinary tract infection: fever, chills, burning pain when you urinate, or back pain ^[1]. Bladder infections can spread to the kidneys, so get treated quickly for fever and chills, nausea or vomiting, or pain in the back, side or groin ^[5].

Get urgent help for smelly urine with any of these ^[2]:

blood in your urine;
lower belly pain;
pain in your back, under the ribs;
feeling tired and unwell;
confusion or agitation;
a very high temperature, or feeling hot, cold or shivery, or a very low temperature.

Seek immediate medical help for signs of ketoacidosis, such as nausea or vomiting, belly pain, confusion, trouble breathing, feeling very tired or sleepy, or fruity-smelling breath, especially if you have diabetes ^[10].

See your provider soon if smelly urine comes with needing to pee suddenly, more often or at night, or with cloudy urine ^[2], or if a new smell does not go away once you are drinking normally.

References

Frequently asked questions

What causes smelly urine?

Most changes in urine odor are not a sign of disease and go away on their own. The common causes are concentrated urine from not drinking enough, foods and drinks such as asparagus, garlic and coffee, and some medicines and vitamin supplements. Less often, a strong or foul smell comes from a urinary tract infection, and a sweet smell can come from uncontrolled diabetes. A urinalysis tells these apart.

How do I stop my urine from smelling?

If the smell comes from concentrated urine or food, drink plenty of fluids, mainly water, so you pee regularly through the day and do not feel thirsty, and drink more in hot weather and when you exercise. Cutting back on lots of coffee, alcohol, sugary fizzy drinks, garlic and asparagus also helps. If the smell stays once you are drinking normally, or comes with burning, urgency, fever or back pain, get a urinalysis rather than trying to mask it.

What should I drink if my urine smells?

Water is the main answer. The NHS advises drinking plenty of fluids, particularly water, so that you pee regularly and do not feel thirsty, and not drinking a lot of sugary fizzy drinks, coffee or alcohol. No specific drink treats an infection. A smell that comes with pain or burning when you pee needs testing, not a different drink.

What does urine smell like when your kidneys are failing?

The National Institute of Diabetes and Digestive and Kidney Diseases does not list a change in urine smell among the symptoms of chronic kidney disease. It says most people with early chronic kidney disease have no symptoms, and the urine changes it lists for advanced disease are foamy urine and a change in how often you urinate. Kidney disease is found with a blood test for creatinine and eGFR and a urine test for albumin.

Does smelly urine mean I have a UTI?

Not on its own. A strong smell is often just concentrated urine, which does not mean an infection. A urinary tract infection becomes more likely when the smell comes with burning when you pee, frequent or urgent need to pee, lower belly pain, or cloudy or bloody urine. The nitrite and leukocyte esterase lines on a urinalysis, and a urine culture, check for infection.

Kidney and urinary health tests

Cystatin C with Estimated Glomerular Filtration Rate (eGFR) Blood Test
A kidney filtration marker that stays accurate when muscle mass throws off creatinine.
Comprehensive Metabolic Panel (CMP)
A 14-marker snapshot of kidney function, liver function, electrolytes, and blood sugar in one draw.