There are several systemic diseases that can cause halitosis (bad breath). They are: chronic liver failure, bronchial or other lung infections, renal failure, carcinoma, trimethylaminuria, diabetes mellitus and metabolic dysfunction. Halitosis from these types of diseases is not originating from the oral cavity. Halitosis stemming from systemic diseases is extremely infrequent in the general population and most cases of halitosis will conclude with the source being from the oral cavity.

Chronic Liver Failure – Fetor hepaticus is chronic bad breath due to liver failure. It is also known as the “breath of the dead”. It is a late sign of liver failure.