Reading the smell
Most bad breath smells like rotten eggs, cabbage or something stale, because bacteria on the tongue and in gum pockets release sulphur compounds. This is the usual pattern, and our page on bad breath explains how to treat it.
Other smells are less common, but they can point somewhere else. You usually cannot smell your own breath reliably, so ask someone you trust, or lick the inside of your wrist, let it dry and smell it.
The smell is only a clue. Do not diagnose yourself from it, and do not panic if one matches.
| Smell | Common source | What to do |
|---|---|---|
| Rotten egg or sulphur | Bacteria on the back of the tongue or in gum pockets | Clean the tongue and between the teeth; see a dentist if it persists |
| Stale or sour | Dry mouth, mouth breathing, reflux | Drink water, check for reflux, see a dentist if it persists |
| Sweet or fruity | Can signal a problem with blood sugar, such as diabetes | See a doctor promptly, especially with thirst, tiredness or weight loss |
| Ammonia or urine-like | Can signal a kidney problem; also very dry mouth | See a doctor |
| Fishy | Can be related to tonsil stones, sinus problems or certain body chemistry conditions | Dentist first, then a doctor if the mouth is healthy |
| Faecal | Repeated vomiting or a bowel blockage | Urgent medical care if with vomiting or belly pain |
| Metallic | Bleeding gums, medicines, supplements | See our guide on metallic taste; dentist if gums bleed |
| Onion, garlic, spices | Food odour carried from the blood to the lungs | Fades in hours; cleaning helps only the mouth part |
Bad breath odour types, common sources and next steps. General information, not a diagnosis.
Smells that start in the mouth
Rotten egg or sulphur smell is the commonest. A stale smell that is worst on waking points to dry mouth or a coated tongue. A foul smell with a bad taste, bleeding gums or a pimple on the gum suggests gum disease or an infected tooth, which needs a dentist.
A cheesy or rotten smell with small white or yellow lumps coming from the throat suggests tonsil stones. Our guide on home remedies for bad breath covers the first steps, and the guide on the tongue scraper for bad breath covers the tongue.
Smells that can come from the body
A sweet or fruity breath, particularly with great thirst, frequent urination, tiredness or weight loss, can be a sign of a blood sugar problem. See a doctor promptly. If the person is also vomiting, breathing fast or confused, that is an emergency.
An ammonia or urine-like smell can occur with kidney disease, and also with a very dry mouth. A faecal smell is unusual and, with repeated vomiting or belly pain, needs urgent medical care. A fishy smell can come from the mouth, nose or sinuses, and rarely from a body-chemistry condition.
Stomach causes are covered in our guide on bad breath from the stomach. Spreading facial swelling, fever, or difficulty swallowing or breathing means same-day care.
Common questions
What does a rotten egg smell on the breath mean?
It usually means sulphur compounds from bacteria on the tongue or in gum pockets. Clean the tongue and between the teeth. If the smell stays, see a dentist to check for gum disease.
Can bad breath be a sign of diabetes?
A sweet or fruity breath smell, especially with great thirst, frequent urination or tiredness, can be. See a doctor promptly. Most bad breath is not related to diabetes.
What does an ammonia smell on the breath mean?
It can be linked to kidney problems or to a very dry mouth. If drinking water and cleaning do not change it, see a doctor.
Can I smell my own bad breath?
Not reliably, because you get used to your own smell. Lick your wrist, let it dry for a few seconds and smell it, or ask someone you trust.
About this page
This page is general information, not a diagnosis or a quotation. Prices are prevailing Lucknow market ranges. Your own treatment and cost are determined after an examination. For questions about your own case, call +91 83036 12717.