There are times when bad breath can occur regardless of the dental health of an individual’s mouth. Bad breath in a healthy mouth is largely a result of microbial deposits on various locations of the tongue, especially the back. In many cases, simply brushing the tongue can reduce bad breath by up to 70 percent.



Saliva contains enzymes that cleanse the mouth of bacterial growth. During sleep, saliva production slows or even stops altogether, producing a dry-mouth effect and causing bad breath.

Certain foods

Certain foods contain compounds that have a strong natural odor, such as onions or garlic which, upon entering the blood stream, are transferred into the lungs, then exhaled through the mouth.

Poor oral hygiene habits

Food particles can remain in the mouth, promoting growth of bacteria.

Periodontal (gum) disease

Inflammation of the gums can often indicate bacterial infections and food particles collecting in hard-to-reach areas.

Dental cavities or ill-fitting dental appliances

Cavities in the tooth or ill-fitting appliances can foster bad breath by allowing hidden areas for bacterial growth and food particle collection.

Dry mouth (Xerostomia)

Dry mouth may result from certain oral medications, salivary gland issues, or sinus problems resulting in excessive mouth breathing. Tobacco products can also dry the mouth and contribute to bad breath. Drinking water throughout the day can keep the mouth clean and moist.


Certain diets can cause ketosis in the body, which produces chemicals called ketones that may be released into the breath as the body burns fat.

Some medical conditions or illnesses

Bad breath can be the body’s response or simply a symptom of such conditions as liver or kidney problems, diabetes, chronic sinus infections, bronchitis and even pneumonia.

If you keep a journal of what and when you eat, you may be able to identify the cause of bad breath. Discuss your current medications, any recent surgeries, or illnesses with your dentist.