Science Reveals Hidden Health Clues in Your Breath Odor
What Your Breath Reveals About Your Health
By Xantha Leatham, Executive Science Editor
Published: 08:57 BST, 26 July 2025 | Updated: 08:57 BST, 26 July 2025
While bad breath (halitosis) is often blamed on poor dental care or coffee consumption, it can also signal underlying health conditions. Dental technologist Allen Zhang highlights five distinct breath odors that may indicate systemic issues, from diabetes to organ dysfunction.
Fruity or acetone-like breath may indicate diabetes-related ketone buildup (Image: Getty).
1. Fruity or Acetone-like
This scent, resembling nail polish remover or pear drops, often points to high ketone levels in the blood—a sign of poorly managed diabetes. When the body can’t process glucose, it burns fat, releasing ketones that create this odor.
2. Metallic
A metallic tang may suggest kidney issues or heavy metal exposure. Kidney dysfunction can lead to urea buildup, which reacts with saliva to form ammonia, causing a metallic smell.
Fishy breath could stem from liver or metabolic conditions (Image: Getty).
3. Fishy
A rotten fish odor may signal trimethylaminuria, a rare metabolic disorder where the body can’t break down trimethylamine. It’s also linked to fetor hepaticus—a musty smell from liver failure caused by toxin buildup.
4. Rotten Eggs
Sulfur-like breath often stems from gastrointestinal issues. Hydrogen sulfide gas, produced during digestion, creates this odor and may indicate gut imbalances or infections.
5. Musty
A musty or “moldy” smell could reflect severe liver or kidney dysfunction. These organs filter toxins; when compromised, harmful substances like dimethyl sulfide accumulate and exit via breath.
Key Health Warnings Linked to Breath Odors
- Fruity/acetone: Diabetes
- Metallic: Kidney dysfunction
- Fishy: Liver disease or metabolic disorders
- Rotten eggs: Gut issues
- Musty: Advanced liver/kidney failure
Beyond Hygiene: A Diagnostic Tool
“These odors are diagnostic clues, not just hygiene issues,” says Zhang, founder of ProDENT, which develops tools for early disease detection. Emerging tech analyzes breath compounds like volatile sulfur or ketones to identify risks.
Persistent unusual breath odors warrant medical attention (Image: Getty).
Common Causes of Bad Breath
While health conditions play a role, everyday factors like poor oral hygiene, smoking, and diet (e.g., garlic, coffee) remain leading causes. Crash dieting can also trigger ketone-related odors. If symptoms persist despite good hygiene, consult a healthcare provider to explore systemic issues.
Final Takeaway: Breath analysis is becoming a frontline tool in preventive care. As Zhang notes, “Your breath isn’t just a reflection of your diet—it’s a window into your overall health.”
For more health insights, visit the NHS guide on halitosis causes.
