Some metabolic disorders can cause bad breath due to various problems in the intestines, blood or liver.

The following are the most important medical conditions that can cause complications:

diabetes

• A common condition that causes bad breath in the mouth and throat is diabetes because high glucose levels can cause the growth of harmful bacteria.
• Because people with diabetes have insulin problems, cells may not get the glucose they need for energy, and instead the body starts burning fat-forming compounds called ketones.
• Ketones accumulate in the blood and urine and cause bad breath.
• One of these ketones is acetone, and it can cause breath to smell like nail polish.
• If someone with diabetes notices the smell, they should seek medical advice as it could be due to diabetic ketoacidosis, a life-threatening condition.

Liver disease

• If a person’s breath has a strong, foul smell, this is a sign that the liver is not filtering out toxins.
• Doctors call this distinctive smell “the breath of the dead” because of its association with severe and fatal liver disease.

Kidney disease

• Chronic kidney disease is a condition in which the kidneys are damaged and cannot filter the blood properly, which is why excess fluids and waste from the blood can build up in the body and cause other health problems such as heart disease and stroke.
• People with kidney failure may develop bad breath.
• As the kidneys begin to fail, the metabolic urea cannot be excreted effectively in the urine, and it accumulates in the blood and saliva.
• The body converts urea into ammonia, which causes bitterness in the mouth and bad breath.
• One in three people on dialysis say their breath smells like urine.

Too much methionine in the blood

• It is an increase in a specific protein building block (amino acid) called methionine in the blood.
• People with this condition often have no symptoms, but if their breath, sweat, or urine smells like boiled cabbage, they should see a doctor.