Causes are several and include major ones like lung abscess, bronchiectasis, pyorrhea, atrophic rhinitis, hepatic failure (fishy odour), uremia (ammoniacal odour), and diabetic ketosis (fruity odour), and smoking and minor and transient ones like ingestion of alcohol, garlic, onion and certain spices in the diet.

Attention to cause. Dental attention. Piodin or Hexidine mouth washes, use of mouth freshener sprays, chewing gum.