Healthy Mouth Healthy Body

Understanding the cause of bad breath

What is bad breath?

Bad breath (also known as malodor) is breath containing an unpleasant odor. This odor can strike periodically or be persistent, depending on the cause. In many patients, the millions of bacteria that live in the mouth (particularly on the back of the tongue) are the primary culprits of bad breath. The mouth's warm, moist conditions make an ideal environment for these bacteria to grow. About 80 percent of bad breath is caused by something in the mouth.

Some types of bad breath, such as "morning mouth," are considered to be fairly normal, and they are usually not health concerns. The "morning mouth" type of bad breath occurs because the saliva that regularly washes away decaying food and odors during the daytime diminishes at night while you sleep. Your mouth becomes dry, and dead cells adhere to your tongue and to the inside of your cheeks. Bacteria use these cells for food and expel compounds that have a foul odor.

In addition, bad breath can be caused by the following:

• Poor dental hygiene – Infrequent or improper brushing and flossing can leave food particles to decay inside the mouth
• Infections in the mouth – Periodontal (gum) disease
• Respiratory-tract infections – Throat infections, sinus infections, lung infections
• External agents – Garlic, onions, coffee, cigarette smoking, chewing tobacco
• Dry mouth (xerostomia) – This can be caused by salivary gland problems, medications or by "mouth breathing"
• Systemic illnesses – Diabetes, liver disease, kidney disease, lung disease, sinus disease, reflux disease and others
• Psychiatric illness – Some people may perceive that they have bad breath, but it is not noticed by oral-health-care professionals or others. This is referred to as "pseudohalitosis."

How do I know if I have bad breath?

A person may not always know that they have bad breath. This phenomenon is based on the fact that odor-detecting cells in the nose eventually become accustomed to the constant flow of bad smells from the mouth. Others may notice and react by recoiling as you speak.

Other associated symptoms depend on the underlying cause of bad breath

• Poor dental hygiene – Teeth are coated with film or plaque, food debris trapped between teeth, pale or swollen gums
• Infections in the mouth – Gums may be red, swollen and bleed easily, especially after brushing or flossing; pus may drain from between teeth; a pocket of pus (abscess) at the base of a tooth; loose teeth or a change in "fit" of a denture; painful, open sores on the tongue or gums
• Respiratory-tract infections – Sore throat, swollen lymph nodes ("swollen glands") in the neck, fever, stuffy nose, a greenish or yellowish nasal discharge, a mucus-producing cough
• External agents – Cigarette stains on fingers and teeth, a uniform yellow "coffee stain" on teeth
• Dry mouth – Difficulty swallowing dry foods, difficulty speaking for a prolonged period because of mouth dryness, a burning sensation in the mouth, an unusually high number of dental caries, dry eyes (in Sjagren's syndrome)
• Systemic illnesses – Symptoms of diabetes, lung disease, kidney failure or liver disease

A dentist or physician may notice the patient's bad breath while the patient is discussing his or her medical history and symptoms. In some cases, depending on the smell of the patient's breath, the dentist or physician may suspect a likely cause for the problem. For example, "fruity" breath may be a sign of uncontrolled diabetes mellitus. A urine-like smell, especially in a person who is at high risk for kidney disease, can sometimes indicate kidney failure.

Your dentist will review your medical history for medical conditions that can cause bad breath and for medications that can cause dry mouth. Your dentist also will ask you about your diet, personal habits (smoking, chewing tobacco) and any associated symptoms described above, including when the bad breath was noticed and by whom.

Your dentist will perform a physical examination, which will include an examination of your teeth, gums, oral tissues and salivary glands. He or she also will feel your head and neck and will evaluate your breath when you exhale from your nose and from your mouth. Once the physical examination is finished, your dentist may refer you to your family physician if systemic problems are the most likely cause. In severe cases of gum disease, your dentist may recommend that you be seen by a periodontist (dentist who specializes in gum problems).

There may be a need for diagnostic tests if the doctor suspects a lung infection, diabetes, kidney disease, liver disease or Sjagren's syndrome. Depending on the suspected illness, these tests may include blood tests, urine tests, X-rays of the chest or sinuses, or other specialized testing.