May 29, 2023

Bad breath can sometimes be a red flag for a range of conditions from diabetes to syphilis that has nothing to do with the mouth.
Our breath can be a sign of our health. About 92% of the time, the causes for bad breath, clinically called halitosis, can be traced back to the mouth. The remaining 8% of the time, bad breath can be a red flag for a range of conditions from diabetes to syphilis that has nothing to do with the mouth. Here’s a quick list of the extra-oral sources of bad breath and what they smell like.
1. Fruity breath: People with diabetes mellitus can have breath that smells like acetone. Diabetes mellitus is a chronic disease in which the blood sugar rises (hyperglycemia), either because the pancreas can’t make the insulin hormone or because the body can’t use insulin properly. And when the body can’t use glucose for energy, it breaks down fats. One of the byproducts of fat metabolism is ketones – which make the breath smell slightly sweet.
Representational image. Image source: Getty Images.
2. Fetid, stinky breath: Syphilis — a sexually transmitted infection caused by Treponema pallidum bacteria — can make a patient’s breath smell really bad. The disease starts as a painless sore on the genitals, rectum or in the mouth. If it goes untreated, it can affect the heart, brain and other organs and even become life-threatening.
3. “Breath of a dead person”: Liver insufficiency or liver failure is a life-threatening situation in which the liver is unable to excrete bilirubin (waste material of liver) or filter blood or perform any of its functions. Technically, the odour from the mouth of a person who has liver failure is called “fetor hepaticus”, which translates as the breath of a dead person.
4. Sour or acidic breath: After the mouth, tummy and intestine problems are the most common reasons for bad breath. Gastroesophageal reflux disease, or GERD, is a condition in which the sphincter muscle at the lower end of the food pipe (oesophagus) is unable to close. The result: the stomach acid can flow back into the oesophagus. Yep, it’s as uncomfortable as it sounds and it can make the patient’s breath smell sour.
5. Fishy smell: Trimethylaminuria, also known as fish odour syndrome or fish malodor syndrome, is a rare metabolic disorder. Patients with this disorder can’t produce an enzyme called flavin-containing monooxygenase 3 (FMO3) which breaks down nitrogen-containing compounds from the diet, including trimethylamine. The result: breath that smells like fish.
6. Smells like ammonia, or pee: Kidney failure is a life-threatening condition in which the kidneys are no longer able to filter the blood – our kidneys absorb water and glucose before removing the waste products of digestion. People with kidney failure may have breath that smells like pee.
7. Burned sugar breath: Maple syrup urine disease is mainly seen in newborns – the patient’s body is unable to process certain protein-building blocks (amino acids). This makes their pee smell sweet and their breath smell like burned sugar. If not treated, this disease can be fatal.
8. Sweet and musty: Homocystinuria, a genetic disease in which the body can’t process the amino acid methionine, can make the breath smell sweet and musty. 
Homocystinuria typically affects infants and can be fatal if not treated.
9. Sweaty feet smell: Isovaleric acidemia is a genetic condition in which the enzyme responsible for the break down of the amino acid leucine stops working, which leads to the accumulation of isovaleric acid in the blood. This condition can be toxic and result in damage to the brain and nervous system. And it can also make the patient’s breath smell like sweaty feet.
10. Rotten meat smell: Bronchiectasis is a condition in which the airways of the lungs become widened, leading to a build-up of excess mucus. The resulting infection in the lungs can make the breath smell like rotten meat.
11. The odour of decay and putrefaction: Lung abscess — a microbial infection that can cause death (necrosis) of the lung tissue and accumulation of necrotic debris into deep cavities (more than 2 cm) — could be the reason a patient’s breath smells putrid.
12. Smells like old blood: Any disease or disorder related to the blood — example, bleeding disorders, coagulation disorders, and red blood cells disorder — can make a patient’s breath smell like blood or like a surgical wound that has just started healing.
13. Decaying wound smell: Liver cirrhosis is a chronic liver condition in which scar tissue forms in the liver – it may eventually lead to liver failure. People with this disorder can have breath that smells like a festering wound.
14. Also smells like ammonia: Azotemia is a biochemical abnormality in which there is an excess of nitrogenous products, creatinine in the blood, and other secondary waste products within the body. It can cause harm to the kidneys, and make the breath smell like ammonia.
15. More dead-people smell: Wegener’s granulomatosis is an autoimmune disease which causes inflammation of the respiratory tract, kidneys and small vessels of the body. People with this disorder can have breath that smells like necrotic putrefactive or death and putrefaction.
16. Poo smell: An obstruction in the intestines can make one’s breath smell poopy.
17. Smells like boiled cabbage: Methionine adenosyltransferase deficiency, a rare genetic disorder in which the body is unable to process methionine properly, can result in intellectual disability in some patients. Typically, though, patients don’t show symptoms apart from having breath that smells like boiled cabbages.
Health articles in Firstpost are written by, India’s first and biggest resource for verified medical information. At myUpchar, researchers and journalists work with doctors to bring you information on all things health. For more information, please read our article on Bad Breath: Causes, Symptoms, Treatment, Prevention.
Updated Date:
The information provided here is intended to provide free education about certain medical conditions and certain possible treatment. It is not a substitute for examination, diagnosis, treatment, and medical care provided by a licensed and qualified health professional. If you believe you, your child or someone you know suffers from the conditions described herein, please see your health care provider immediately. Do not attempt to treat yourself, your child, or anyone else without proper medical supervision. You acknowledge and agree that neither myUpchar nor firstpost is liable for any loss or damage which may be incurred by you as a result of the information provided here, or as a result of any reliance placed by you on the completeness, accuracy or existence of any information provided herein.
The World Health Organization (WHO) has already delivered their statement that neither swishing nor gargling with mouthwash can kill the COVID-19 virus.
Most mouthwash solutions contain active compounds that work together to limit the growth of bacteria that cause plaque.
You will be amazed to know that most of the cavities are seen on the sides of the teeth and not the top.
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