What causes bad breath?

What causes bad breath?

Bad breath plagues just about everyone at one time or another. Bad Breath is devastating for ones social life. Many people have been denied employment, failed in business and social engagements and relegated to low social status because of it.

There are four sources of bad breath:

  1. The mouth
    This includes the teeth, the gums, and the top surface (dorsum) of the tongue, especially the very back of the tongue. Since this type of bad breath is the most common, its diagnosis and treatment will be covered extensively.
  2. The upper respiratory tract
    Including the nasal cavities, sinuses, throat, tonsils and the larynx (voice box). This is the second most common type of bad breath.
  3. The lungs
    This could be a temporary issue caused by consumption of certain foods, drugs, or a chronic issue caused by a disease.
  4. The stomach
    This type of bad breath could be caused by diseases, which could cause chronic vomiting.

80% of all bad breath originates from bacterial overgrowth in the mouth. If you are young, healthy, and do not suffer chronic sinusitis, tonsillitis or laryngitis, chances are good that this section is the most relevant to your problem.

Sulfur compounds created by these bacteria causes the bad breath in the mouth. Anaerobic bacteria grow in the absence of oxygen and produce a chemical call Volatile Sulfur Compound (VSC) which includes things such as rotten egg smell, rotten cabbage smell, and rotten vegetable smell. The anaerobic bacteria metabolize proteins such as dead tissue cells, blood and mucous. Proteins are made from building blocks called amino acids, and the digestion of these amino acids supply the bacteria with energy. Some of the amino acids contain sulfur, and these sulfur compounds are converted to VSC’s as a waste product.

In a healthy mouth there is no bad smell because there is a balance of bacteria flora in the mouth. When the conditions in the mouth change due to disease or other factors such as dehydration or the presence of fermentable substances such as blood, dead cells and shreds of food, the balance of bacteria changes, allowing the overgrowth of anaerobic bacteria at the expense of the rest of the normal floral organisms. The bad odor becomes the result.

There are several chronic or temporary conditions that can shift the balance of bacterial flora toward an overgrowth of the bacteria which produce VSC’s:

Xerostomia or Dry Mouth

Dry mouth dehydrates and creates a concentrated mucous coat over the teeth. The most common type of bad breath caused by dry mouth is morning breath, which is a result of breathing through the mouth while sleeping. Sjorgren’s Syndrome, aging and consumption of numerous drugs cause further dry mouth as well.

Some drugs actually cause Halitosis (not originating in the mouth). Recovery room and operating room personnel can all attest to the incredibly bad breath (originating from the lungs) exhaled by patients recovering from general anesthetic agents after operations.
Illegal recreational

Due to lifestyle diet changes and damage from the Illegal drug use, there are tooth decay, poor oral hygiene, and gum disease that can be added to this group as well. have the added liability of lifestyle issues which interact with the dry mouth and make the bad breath much worse.

People who have high sugar intake, tend to have bad breath, since the sugar sticks to the teeth, harboring bacteria and decaying of the teeth. Decay inside a tooth provides an anaerobic environment and is thus a great place to live if you are a sulfur metabolizing germ. This decaying (dead tooth structure) of the tooth, harbors anaerobic bacteria. Dead things smell bad and since the decay is fairly soft, it absorbs juices from the foods you eat, and that decays as well. As a result, the first place to start on the road to recovery from bad breath is a visit to the dentist for a check up for decay.

Even without decay, if the oral hygiene is poor a film of plaque which is composed of bacteria and food debris, accumulates on and between the teeth. Bacteria in the plaque produce VSC’s, causing bad breath. In healthy individuals, this type of bad breath can generally be eliminated simply by brushing and flossing the teeth properly once a day. Flossing is essential since the area between the teeth is more likely to be free of oxygen than any other area of the mouth, and therefore is always a source of bad breath if not kept clean. If you have a problem with bad breath, try smelling a piece of floss after using it to clean between the teeth and see for yourself.

The Gums or Periodontium

The periodontium is composed of bone and gums. In its healthy state, the periodontium is not prone to harboring bacteria, and therefore does not contribute to bad breath. However, when the periodontium is diseased due to bad oral hygiene (due to either lack of brushing or flossing), bacteria begin to eat away at the attachment of the gums to the tooth, and the bone that holds the tooth starts to get destroyed (periodontal disease). As the bone gets destroyed a space is created between the gums and the bone, called a pocket, more and more food and bacteria and dead stuff accumulates in this space, which provides an oxygen inhibited area, which is a perfect growth area for the anaerobic bacteria. As a result, the gums become red and inflamed, and will bleed. The anaerobic bacteria digest the blood and necrotic (dead) gum tissues producing lots of VSC’s.

Bad breath from periodontal disease is the worst bad breath there is. If you have bad breath, and you are not cleaning between your teeth on a regular basis, then the chances are good that you are suffering from at least minor periodontal disease. A dentist can diagnose and treat this condition if you wish to eliminate bad breath. Partially impacted wisdom teeth may also cause bad odor. The cure for bad breath caused by impacted wisdom teeth is the removal of the offending tooth/teeth by an oral surgeon.


The top surface of the tongue is covered with structures called papillae. They are the microscopic hairlike projections that produce the pink, velvety coating on the top surface of a healthy tongue. The Shedding of the filliform papillae is slower on the back part of the tongue compared to the front, as a result, the papillae there tend to grow longer. These longer hairs are an ideal place for bacterial colonies to hang out. Anaerobic bacteria thrive within the continuously forming layer of mucous, food debris, dead cells and dead bacteria that is always present in this area. To eliminate odor due to plaque and bacterial build up over the tongue, one must simply scrape the tongue vigorously all the way to the back side of the tongue. Make sure you stick your tongue out all the way, take a look at the back end of your tongue and make sure that you are scraping this section very well. Performing this routine at night time, will also reduce the morning breath as well.

It is normal to gag during this process, however, persistence pays off, and the gagging subsides over time as you get used to it. Remember, this scraping must be vigorous enough to give your tongue a “haircut”, but not so vigorous that you cause pain or bleeding. If you look at (or smell) the material that you scrape off the tongue, you will see why there is so much potential for bad breath from it. Gargling and brushing your tongue with 1.5% hydrogen peroxide ( generally the hydrogen peroxide sold at stores are 3% so you may dilute with water 50%) will help to get rid of the compounds left behind as a by product of the anaerobic bacteria. This accomplishes two things, the oxygen released from hydrogen perdoxide, combines with VSC’s and neutralizes them, not only that but also it kills the anaerobic bacteria.

Bad breath caused by structures in the upper respiratory system (Ozostomia) are completely different. These are:

Sinusitis and post nasal drip

Although sinusitis does not directly cause bad breath, it produces a large amount of mucous which tends to drip down the back of throat, coating both the back of throat and tongue ( post nasal drip, which has a sour tasting sulfur smell to it and because this thick layer is stuck to the back of the throat, it forces the patient to do forceful swallowing constantly..

The cure for post nasal drip is to treat the condition causing it.

The common cold, flu or allergy often cause post nasal drip. Ultimately, the cure for post nasal drip due to these conditions is to wait them out. There are certain medications that may be taken to speed up the recovery process. Sudafed, Guaifenesin and antihistamines are good medications to be used to relieve some of these symptoms faster. At times antibiotics might be useful.

Tonsillitis and Tonsilloliths

The infection of the tonsils. Antibiotics are usually prescribed for these instances. For recurring tonsillitis in children, it is recommended for the tonsils to be evaluated for their removal. At times these tonsils can create airway obstructions, which can lead to snoring, lack of sleep, allergic shiners under the eyes, mouth breathing at night or day, lack of attention, tiredness or even hyperactivity, poor school performance, and even ADHD. The tonsils and the airways must be evaluated by dentists who have proper training in this arena and be referred to the proper specialists. Neuromuscular Dentists in general always evaluate the airways and posture of the children.


Bad breath caused by disease processes in the lungs such as bronchitis and pulmonary abscess, as well as chronic problems like tuberculosis, pneumonia, emphysema, and lung cancer. Prolonged bed rest can cause mucous accumulation which can lead to bad breath. Cigarette smokers suffer from the same problem as well.


Bad breath stemming from systemic metabolic conditions is a term invented in 1921 by the Listerine company. The bacteria and chemicals from systemic disease are carried to the lungs via the bloodstream. Halitosis is also the term used to describe mouth and throat odor due to vomiting. There are three types of halitosis:

  • Physiologic halitosis is temporary and is a result of eating certain aromatic foods such as herbs, spices, certain cold cuts, curries, onions, garlic, radishes, turnips and leeks, or drinks certain types of liquids such as wine, brandy, whisky, liqueurs, beer, tea and coffee. Foods such as these are the most common source of transient (temporary) bad breath, and the cure for physiologic halitosis is simply to avoid aromatic foods, or to wait out the effects.
  • Pathological halitosis originates in the lungs due to a disease process. This is not easily reversible. One must first treat the underlying conditions. Some of the common condition that cause pathologic halithosis are diabetes, Uremia, Gastritis, Gastric Ulcer, Liver disease or hepatitis.
  • Pathological halitosis originating in the stomach is caused by conditions which produce chronic vomiting which coats the throat and mouth, creating a foul odor.
  • Acid Reflux Disease (ARD–Formerly known as GERD)–This is generally controlled using H2 blockers like Tagamet, Zantac or Pepsid.
  • Pyloric Stenosis–A developmental condition found in infants which causes vomiting, and is corrected surgically.

Some other conditions that cause chronic vomiting and result in pathoogic vomiting are migraine headaches, morning sickness, food poisoning, food allergies, bulimea, alcoholism, certain medications and chemotherapy.

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