Topic Overview

When is bad breath most likely to occur?

has bad breath from time to time, especially first thing in the morning. You
also may have bad breath when you are hungry, when you are dieting, or after
eating foods with a strong odor, such as garlic, onions, or pastrami.

What causes bad breath?

Many things can cause bad
breath. A major cause is decreased
saliva. Saliva has a cleaning action that helps reduce
or eliminate bad breath. When saliva decreases, bacteria can grow, causing bad

Bad breath caused by a decrease in saliva may be
especially noticeable:

  • In the morning. The flow of saliva almost
    stops during sleep. The reduced cleaning action of the saliva allows bacteria
    to grow, causing bad breath.
  • When you are hungry. Bad breath is
    more common in people who miss meals or are dieting. Chewing food increases
    saliva in the mouth. When you are not eating, saliva decreases and bacteria
    growth increases, causing bad breath.
  • When you are
    dehydrated. When you become dehydrated, you do not
    produce as much saliva. The reduced cleaning action of the saliva allows
    bacteria to grow, causing bad breath.
  • From diseases that affect the
    salivary glands, such as
    Sjögren’s syndrome or
  • When you are taking certain
  • After drinking alcohol beverages.

Other causes of bad or changed breath include:

  • Eating foods with a strong odor, such as
    garlic, onions, or pastrami.
  • Smoking or using smokeless (spit)
    tobacco, such as snuff or chewing tobacco.
  • Bacteria and
    plaque buildup in the mouth from food caught between
    teeth, dentures, or dental appliances.

Mouth and throat problems that can cause mouth odor

  • Throat or mouth infections, such as
    strep throat.
  • Dental problems, such as
  • Gum disease (periodontal disease), which may cause a metallic breath odor.
  • Tonsils with deep tunnels (crypts) that trap food
  • Throat or mouth cancers.

Problems in other areas of the body that can cause mouth
odor include:

  • Problems with the nose, such as a sinus
    nasal polyps, or an object in the
  • Diabetes. A symptom of very high blood
    sugar is a strong, fruity breath odor.
  • Digestive system disorders,
    such as reflux (gastroesophageal reflux disease), bowel problems, or
  • Human immunodeficiency virus (HIV) infection.
  • Liver
  • Lung problems, such as an infection or cancer.

How is bad breath treated?

To help improve your

  • Gargle with water.
  • Brush your
    teeth, tongue, roof of your mouth, and gums at least twice a day with
  • Floss your teeth once each day.
  • Eat a
    low-fat diet rich in fruits and vegetables.
  • Eat less meat.
  • Do not smoke or use other tobacco products, such as snuff or
    chewing (spit) tobacco.
  • Avoid foods and drinks that cause bad
    breath, such as garlic and alcohol.
  • Eat at regular intervals.
    Dieting or missing meals can decrease saliva and cause bad breath.
  • Chew sugar-free gum, suck on sugar-free mints, or drink water,
    especially if your mouth is dry. Try using breath sticks, which contain the
    ingredients found in a mouthwash and dissolve in your mouth.
  • Remove
    dentures, removable bridges, partial plates, or orthodontic appliances and
    clean them once each day or as directed by your dentist. Pieces of food and
    germs can collect on these appliances and cause bad breath.
  • Use a
    mouthwash for temporary relief of bad breath. Swish it around in your mouth for
    30 seconds before spitting it out.
  • Have regular dental
  • Make an appointment to see an ear, nose, and throat
    specialist (otolaryngologist) if you have frequent problems with
    mouth odor.

Related Information


ByHealthwise Staff
Primary Medical Reviewer William H. Blahd, Jr., MD, FACEP – Emergency Medicine
Adam Husney, MD – Family Medicine
Martin J. Gabica, MD – Family Medicine

Current as ofMay 7, 2017