Halitosis (bad breath) is something everyone experiences from time to time. But “morning mouth” or a spicy oral aroma after eating an occasional garlic-laden Italian meal is where it should stop. If you have consistently bad breath, this is an indication that something else is going on that needs to be addressed.

What Causes Halitosis?

Bad breath can result from a number of different lifestyle habits, poor oral hygiene and certain medical conditions. Here is an overview of the more common causes:

Odor-Generating Foods

Foods that have a strong odor commonly cause bad breath. This smell persists even after you brush your teeth. That’s because the smell is not necessarily coming from food residue in your mouth. Certain spicy or pungent compounds in the food/beverage you ingested have passed through your digestive system into your bloodstream. From there, they are expelled from your body through your lungs – making your breath smell bad. This odor may persist for about six hours before dissipating as your body clears the offending substances.

Poor Dental Hygiene

Failure to brush and floss thoroughly (including brushing or scraping your tongue daily) and the development of infections like periodontitis or cavities can lead to halitosis. These conditions all support the growth of oral bacteria. These bacteria produce waste compounds that smell foul. If actual bits of food are left in between your teeth, these can rot and add to the bad smell. This is a frequent problem with poorly fitted dental restorations that make proper cleaning difficult.

Dry Mouth

Saliva plays an important role in limiting bacteria growth and cleansing the surfaces of your teeth, gums and tongue on an ongoing basis. When the salivary glands are not functioning properly, bacteria levels tend to rise, increasing mouth odor. Dry mouth can be caused by various medical conditions. However, it is often medications that cause dry mouth as a side effect. Breathing through your nose instead of your mouth can contribute to this problem as well.


Cigarette smoking and use of smokeless tobacco products cause chronic bad breath in a number of ways. First, the substances in the tobacco products have an odor that most non-users find unpleasant. Tobacco can also reduce saliva flow, leaving bacteria to flourish. Smoking is a leading factor in the development of gum inflammation and periodontal disease, another common cause of halitosis.

Sinus Drainage

Infections or allergies that cause drainage down the back of the throat can contribute to halitosis. Some bacteria thrive on this mucous and can make your breath smell bad even when you brush and floss regularly. These patches of bacteria may be at the back of your tongue where it is difficult to brush effectively. You may also see white spots on your tonsils that are actually accumulation of bacteria.

Systemic Infections or Diseases

There are a very wide variety of illnesses and disorders that can lead to halitosis. These include:

  • Diabetes (breath has a fruity odor)
  • Yeast infection (creates a furry white coating on the tongue)
  • Lung infections such as pneumonia
  • Chronic acid reflux
  • Kidney or liver disease
  • Alcoholism
  • Peptic ulcer
  • Cancer

How Is Halitosis Treated?

Using breath fresheners is a solution for temporary or occasional bad breath, but it is important to find the root source of the odor and not just cover it up. The long-term, effective treatment of halitosis must address the underlying cause. Proper oral hygiene is the first line of defense against bad breath (and helps ensure you don’t develop periodontitis). However, if your bad breath isn’t being caused by an oral infection or lack of good hygiene in your mouth, your dentist will likely refer you to a physician for evaluation or testing. Making changes to your diet, quitting smoking and addressing symptoms of dry mouth can all help in treating and preventing bad breath.