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Symptoms and Signs of Bad Breath (Halitosis)

Doctor's Notes on Bad Breath

Bad breath (halitosis) can be an embarrassing problem. Most causes of bad breath are due to poor oral hygiene, but bad breath can be caused by a number of things, including diet, dry mouth, tobacco products, medication, use of dental appliances, and conditions such as diabetes, gastroesophageal reflux disease (GERD), lactose intolerance, gum disease, respiratory tract infection, sinusitis, and others. Treatment for bad breath depends on the cause but maintaining proper oral health can help reduce or eliminate bad breath in many cases.

People who have bad breath may not be aware they have it, or their symptoms may be temporary. Symptoms of bad breath include bad breath smell, bad taste in the mouth, sour taste or taste changes, dry mouth, or a coating on the tongue.

Medical Author: John P. Cunha, DO, FACOEP
Medically Reviewed on 3/11/2019

Bad Breath
(Halitosis) Symptoms

Many individuals with bad breath may be unaware they have it, or their signs and symptoms may only be temporary. The odor often depends upon the source or underlying cause of the bad breath.

Some common symptoms of bad breath include

  • bad breath smell,
  • bad taste in the mouth, sour taste, or taste changes,
  • dry mouth,
  • a coating on the tongue.

Bad Breath
(Halitosis) Causes

Bad breath (halitosis) can be caused by a variety of things, including diet, medication, poor oral hygiene, and diseases or conditions such as diabetes, GERD, lactose intolerance, gum disease, and more. Treatment for bad breath depends on the cause.

Medications that cause a dry mouth can trigger bad breath. In addition, certain medications, such as triamterene and paraldehyde, have bad breath as a side effect.

Causes of bad breath include the following:


  • When a person does not brush or floss their teeth thoroughly, food particles that may remain in the mouth can rot and cause foul odors. In addition, food particles over time can promote the growth of bacteria, which can also cause foul odors. The bacteria can also lead to tooth decay and gum disease.
  • Foods with strong odors also affect the air a person exhales. Foods commonly known to contribute to bad breath include onions and garlic, exotic spices (such as curry), some cheeses, fish, and acidic beverages such as coffee. These foods may also cause stomach and gastrointestinal upset and belching, which can contribute to bad breath. In addition, certain supplements, such as fish oil capsules, can contribute to bad breath.
  • Low-carbohydrate diets may also cause what is known as "ketone breath." So-called "low carb" diets cause the body to burn fat as its energy source. The end product of making this energy is ketones, which cause a fruity acetone-like odor on the breath when exhaled.

Dry Mouth

  • Bad breath can also be caused by decreased flow of saliva, which is a vital part of the digestive process and removes odor-causing particles in the mouth. Also called xerostomia, dry mouth may be caused by medications, breathing through the mouth, or salivary gland problems.

Tobacco Products

  • In addition to causing bad breath, smoking or chewing tobacco-based products can stain teeth, irritate gum tissue, and exacerbate tooth decay.

Medical Disorders

The following medical disorders may cause bad breath:

Dentures or Dental Appliances

  • Dentures or dental appliances, such as braces, can contribute to bad breath. Most often, it is due to food particles that are not properly cleansed from the appliances. Loose-fitting dentures can contribute to sores and localized infections in the mouth, which can cause bad breath.

Morning Breath

  • Overnight, bacteria accumulate in the mouth, which can cause bad breath, commonly referred to as "morning breath." Some people breathe through their mouths at night, which can cause dry mouth and worsen morning breath.

Bad Breath (Halitosis) 17 Causes and How to Get Rid of It Slideshow

Bad Breath (Halitosis) 17 Causes and How to Get Rid of It Slideshow

Beers with the boys, a girls’ night out over wine, an after work happy hour. These are all a recipe for fun, but your partner may notice something less fun in the morning—your bad breath.

Unlike most liquids, alcohol dries your mouth out which aids bacteria to cause bad breath, also known medically as halitosis. Caffeinated beverages can do this too, and so can cigarettes and spicy food. This prevents your natural mouth-cleaning agent, saliva, from doing its job. When saliva’s not on patrol, bacteria thrive, leaving your mouth less than minty-fresh.

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Kasper, D.L., et al., eds. Harrison's Principles of Internal Medicine, 19th Ed. United States: McGraw-Hill Education, 2015.