Acetone smell in urine: causes, tests, and what to do

When people say their urine "smells like acetone" or "fruity/sweet," they're most often referring to ketones—fat breakdown products excreted in urine and exhaled air. One of these, acetone, has a characteristic "fruity-sweet" odor. The presence of moderate to high ketones can be harmless (for example, during short-term fasting or a keto diet), or it can be a symptom of dangerous conditions such as diabetic ketoacidosis (DKA), an acute complication of diabetes. It's important to distinguish "physiological ketosis" from "ketoacidosis" based on accompanying symptoms and tests. [1]

It's important not to confuse the acetone smell with ammonia ("pungent, caustic"): the latter is more often associated with dehydration or a urinary tract infection, as well as certain foods (for example, asparagus produces a sulfurous "aroma"). This is different and usually not related to ketones. If urine is darker than usual and has a stronger odor, first consider your fluid intake and a possible infection. [2]

In children, an "acetone" odor most often accompanies ketosis due to illness/vomiting (the so-called "acetonemic" episode) or cyclic vomiting; in pregnant women, ketonuria is possible with toxicosis and starvation. In diabetes, any "acetone" odor plus high glucose levels is a reason to immediately check for ketones and seek medical attention without delay. [3]

Finally, isopropyl alcohol (isopropanol) can produce a strong acetone odor (due to conversion to acetone), ketones in the urine, and “intoxication,” but without pronounced acidosis—this is a separate toxicological story and also requires a physician’s assessment. [4]

A quick cheat sheet for odor analysis

Sometimes the smell alone can lead to a diagnosis. But always consider the overall picture: how you feel, your temperature, your blood glucose levels, your pain, and changes in urine color.

Table 1. What is most often behind different urine odors?

How to describe a smell	Probable cause	What else happens?	Comments
"Fruit/acetone", sweetish	Ketones (ketosis/ketoacidosis), sometimes isopropanol	Thirst, frequent urination, nausea, fruity breath	In diabetes, thinking about DKA is urgent. [5]
"Ammonia", sharply caustic	Dehydration, UTI	Dark urine, burning/frequent urination, fever	Most often it’s not about ketones. [6]
"Sulfur", "pharmacy" after meals	Asparagus, B vitamins	The smell goes away within 4-14 hours	Safe. [7]
"Fish"	Trimethylaminuria (rare)	It smells like sweat/breath	Inherited metabolism of TMA. [8]

The main causes of the "acetone" smell

1) Diabetic ketoacidosis (DKA)

DKA is an acute complication of diabetes (usually type 1), in which, due to insulin deficiency, the body suddenly switches to ketogenesis: ketone bodies and acids accumulate in the blood, and pH drops. Classic symptoms include intense thirst, frequent urination, nausea/vomiting, abdominal pain, general weakness, difficulty breathing deeply (Kussmaul's syndrome), "fruity" breathing, and sometimes confusion. This is an emergency requiring infusions/insulin/electrolyte correction in a hospital setting. [9]

Home urine ketone tests and portable β-hydroxybutyrate analyzers can help suspect DKA. Practical thresholds for blood: ≥1.6-3.0 mmol/L - risk of DKA, >3.0 mmol/L - very likely DKA; for urine, "2+" or higher on a urine test in a diabetic is a reason for urgent evaluation. Remember that the standard urine nitroprusside test does not detect β-hydroxybutyrate (the main ketone in DKA), so the severity can be underestimated based on urine alone - blood is preferable. [10]

If you have diabetes and experience an acetone odor, high glucose, nausea/vomiting, or abdominal pain, these are red flags. Guidelines advise not to delay seeking medical attention; DKA can develop within hours, especially with an infection or missed insulin dose. [11]

The diagnosis of DKA is confirmed by: hyperglycemia, ketonemia/ketonuria, metabolic acidosis (low HCO₃⁻, pH), and an elevated anion gap. Treatment includes rehydration, intravenous insulin, correction of potassium and underlying causes (infection, etc.). This is always the responsibility of emergency care. [12]

2) “Physiological” ketosis: fasting, low-carb/keto diet, pregnancy/lactation, alcoholic ketosis

Low to moderate ketone levels are possible with carbohydrate deficiency (overnight fasting, skipping meals, strict diets). In healthy people, this is usually harmless and resolves with carbohydrate intake and hydration. However, be aware of how you feel: weakness, headache, and nausea are all reasons to reconsider your diet and fluid intake. [13]

During pregnancy, ketonuria often accompanies morning sickness, especially with vomiting and poor nutrition. Fluid intake and slow carbohydrates usually reduce ketone levels; if vomiting and weight loss are severe, an obstetrician should evaluate the risk of dehydration and deficiencies. The "acetone smell" itself during pregnancy is not a diagnosis, but a signal to improve nutrition and rule out hyperglycemia if gestational diabetes is suspected. [14]

Alcoholic ketoacidosis occurs in people after several days of alcohol consumption/fasting: acetone odor may be present, glucose is sometimes normal/low, and nausea/vomiting occurs. This condition also requires medical attention (IV fluids, electrolytes, glucose, thiamine), but the mechanism and treatment differ from DKA. [15]

Children are more prone to ketosis due to infections and poor appetite ("accelerated starvation of childhood"): an "acetone" odor, vomiting, and lethargy develop. In most cases, oral rehydration with glucose (sweet tea, carbohydrate-containing rehydration solutions) and frequent feedings are helpful; if vomiting is repeated, hospitalization is recommended. It is important to distinguish this from the onset of diabetes mellitus; if in doubt, check your glucose levels. [16]

3) Isopropyl alcohol (isopropanol) poisoning

Isopropanol (a solution in household rubbing alcohol) is metabolized into acetone. This results in an acetone odor and ketonuria/ketonemia, but without acidosis ("ketosis without acidosis"). The clinical picture resembles alcohol intoxication, with possible CNS depression, vomiting, abdominal pain, and an osmolar "gap" in the blood. Treatment is supportive, including hemodialysis in severe cases. If suspected, hospitalization is recommended. [17]

What else is often mistaken for "acetone" but is not it?

A strong ammonia smell indicates dehydration and/or a urinary tract infection; often accompanied by turbidity, burning, frequent urination, fever, or lower abdominal/lower back pain. These cases require a general urine analysis and, if symptoms of a UTI are present, antibiotic therapy. [18]

Food and vitamins. Asparagus produces a characteristic sulfurous odor (not acetone), while B vitamins and certain foods temporarily alter the color/odor of urine and are harmless. The odor usually disappears within hours of cessation of exposure. [19]

Rare metabolic conditions. For example, trimethylaminuria (a "fishy" odor to sweat/urine/breath). This is not about ketones; the diagnosis is based on genetics/biochemistry and is treated with diet and measures to reduce TMA. [20]

In most situations, changes in urine odor are short-lived and harmless; if the odor is new, persistent, and accompanied by pain, fever, cloudy urine, or blood, consult a doctor. [21]

How to get tested: home steps and medical advice

Step 1: Self-assessment. Are you thirsty, nauseous/vomiting, have abdominal pain, rapid breathing, or confused? Are you diabetic? Are you pregnant? Is your child sick and refusing to eat? This determines the urgency. [22]

Step 2. Home tests (if available). For diabetes, measure glucose and ketones. For blood, the following guidelines apply: <1.0-1.5 mmol/L - usually not DKA; 1.6-3.0 mmol/L - risk of DKA, contact your team; >3.0 mmol/L - suspected DKA, call an ambulance/emergency room. Urine dipsticks are useful but underestimate the severity of DKA because they measure primarily acetoacetate, not β-hydroxybutyrate. [23]

Step 3. In the clinic. General urine analysis (ketones/glucose/leukocytes/nitrites), blood glucose, blood β-hydroxybutyrate, blood gases/electrolytes (for acidosis), urine culture in case of infection. If toxicology is suspected, osmolar gap, toxicology screening. [24]

Step 4. Special situations. For children with "acetonemia" without diabetes, focus on oral rehydration with carbohydrates; in case of uncontrollable vomiting, infusions. For pregnant women, rule out dehydration and hyperglycemia, establish nutrition; in case of persistent vomiting/weakness, hospitalization is recommended. [25]

Table 2. Home thresholds for ketones (guidelines)

Test	Norm	Gray range	Alarm/Actions
Blood (β-GB)	<0.6 mmol/L	0.6-1.5 mmol/L - retest in 2 hours	≥1.6-3.0 mmol/L - contact your doctor; >3.0 mmol/L - call an ambulance/go to the hospital
Urine (strip)	negative/traces	1+ - observation, drinking, carbohydrates	≥2+ in a diabetic - suspected DKA/hospitalization
Based on NHS and ketone monitoring reviews. Be aware of the limitations of urine testing for DKA. [26]

When to See a Doctor Urgently (Red Flags)

• Diabetes + high blood sugar, nausea/vomiting, abdominal pain, difficulty breathing deeply, weakness/drowsiness, "fruity" odor. This is DKA until proven otherwise. [27]
• Anyone with an "acetone" odor + repeated vomiting, dehydration, confusion. [28]
• Suspected ingestion of isopropanol/"industrial alcohol" - seek immediate medical attention. [29]
• A child who is unable to hold anything down, is lethargic, and smells of acetone - should be examined today (sometimes infusion therapy is needed). [30]

What you can do yourself (if there are no “red flags”)

1. Drink plenty of water/oral rehydration solutions. This reduces urine concentration and helps with mild ketosis from fasting/dieting. [31]
2. Add carbohydrates (unless you're diabetic and following a planned keto diet): Small servings of complex carbohydrates reduce ketogenesis. If you have diabetes, follow a "chick-day" plan with your team. [32]
3. Rethink your diet: too strict low-carb plan → slow down; during pregnancy, eat more often and in small amounts. [33]
4. If the smell is more like ammonia and there is burning/cloudy urine/fever, it could be a UTI: a urine test and treatment are needed. [34]

Frequently Asked Questions (FAQ)

• Does the smell of acetone always mean diabetes?

No. Ketones can appear during fasting, dieting, vomiting, alcohol consumption, and pregnancy. However, in people with diabetes, the combination of "acetone odor, high blood sugar, and malaise" is a reason to rule out DKA. [35]

• My urine strips showed 2+ ketones, but I feel fine. Is this dangerous?

For non-diabetics and asymptomatic individuals, this may be temporary ketosis (food/fasting/exercise). Drink water, add carbohydrates, and retest. However, for diabetics, a "2+" result is a reason to take action/contact a doctor. Keep in mind that a urine test does not measure β-hydroxybutyrate and may underestimate DKA. [36]

• Why do they talk about "fruity breath" and not urine when they have DKA?

Because acetone is also released in the exhaled air, a "fruity" breath odor is a classic clinical marker. However, urine can also have a sweet/acetone-like odor due to ketones. The absence of odor does not rule out DKA. [37]

• How to distinguish "acetone" from "ammonia"?

Acetone has a sweet, fruity flavor; ammonia has a sharp, ammonia-like odor. Ammonia is often associated with dehydration/UTI or food (asparagus), while acetone is associated with ketones. When in doubt, rely on your symptoms and get tested. [38]