8 contributing issues & risk factors for bad breath.

- How Dry Mouth (morning breath, xerostomia), Smoking, Gum Disease, Sinus Conditions, Foods, Medical and Dental Conditions can cause or promote halitosis.


Link to gum disease section.


Link to sinus conditions section.

This page outlines a number of factors that can make it more likely that you'll have problems with halitosis. They include:


As you read through the explanation of each of these issues, take notice of how many of them directly relate to:

  1. Conditions that promote the growth of oral bacteria.
  2. Situations that make it more difficult to clean those areas where oral bacteria reside.

These issues are important because they're the actual reasons why you have bad breath. The co-factors discussed on this page just help to set the stage for them.

Note: If there's something in our text below that you don't understand, the following links will provide the answers you need:

Risk and contributing factors for halitosis -

A) Dry mouth.

Morning breath.

Everyone, even including people who don't really have much of a mouth odor problem, probably notice that their breath is least pleasant in the morning when they first wake up. (As opposed to the term "bad breath," the words "sour" and "stale" are often used to describe what's noticed.)

This occurs because during the night a person's mouth tends to dry out, due to their body's natural tendency to lower their flow of saliva as they sleep. And if you snore or sleep with your mouth open, it tends to aggravate this situation even more.

In most cases, morning breath can be expected to disappear after a person has performed their morning oral hygiene and has had a chance to rehydrate their mouth.

Similar conditions.
  • This same type of drying/souring event is often noticed by teachers, lawyers, or anyone else who must speak for extended periods of time.
  • People who routinely breathe through their mouth, or are fasting or else find themselves stressed (these situations tend to reduce salivary flow), may find they have a chronically dry mouth and thus persistent problems with breath malodor.

Why oral moisture is so important.

An explanation for the dry-mouth phenomenon lies in the fact that oral moisture helps to keep a person's mouth clean.

  • The presence of oral fluids encourages us to swallow. And with each swallow we take we expel bacteria from our mouth, as well as the food and debris on which they feed.
  • Oral moisture dilutes and washes away the smelly waste products that oral bacteria produce.
  • Saliva is the body's natural mouth rinse. It contains compounds that kill bacteria and buffer their stinky waste products.

So, when our mouth dries out, each of these mechanisms is inhibited to some degree, with the net result being one where the conditions for bacterial growth are enhanced, while the neutralization of their odoriferous waste products is diminished.

B) Xerostomia.

Some people have a chronically dry mouth, a condition termed "xerostomia." It's suggested that this is the underlying cause of a person's halitosis in about 3% of cases.

Section references - Quirynen

Common causes.

Medicines - Xerostomia can be a side effect of taking certain types of medications.

This includes antihistamines (allergy and cold medications), antidepressants, blood pressure agents, diuretics, narcotics, or anti-anxiety medications may all be contributing factors for this condition.

Age - As a person gets older, a condition of chronic mouth dryness may become more and more of a problem.

That's because a person's salivary glands tend to work less effectively as they age, and the composition of the saliva they produce changes too.

Gum disease as a complicating factor.

People who have xerostomia are at greater risk for developing gum disease and the breath issues that come with it (see our next section).

A part of this risk is associated with the relatively dried-out nature of the person's dental plaque, thus making it more difficult to remove. Also, some level of the protection that saliva provides (such as washing away and buffering oral bacteria and the compounds they produce) is lost too.

C) Smoking.

You're probably familiar with the odor of people who have "smoker's breath." As it turns out, dealing with it is difficult because the smoking habit both causes and promotes halitosis. Here's how:

Cigarette smoke contains VSC's.

The odor of bad breath is caused by a class of molecules collectively referred to as volatile sulfur compounds (VSC's). And in the case of smokers, not only does their breath contain some level of VSC's that have been produced by oral bacteria but it also contains additional levels derived directly from their cigarette's smoke.

That means that short of quitting smoking, there's no cure for smoker's breath. Although, practicing immaculate oral hygiene (and thus reducing the level of intra-oral VSC's produced) may help to minimize it.

A 'No Smoking' sign.

Smoking can aggravate breath problems.

Ways smoking aggravates breath problems.

Smoking dries out oral tissues.

The dry-mouth conditions associated with smoking typically correlate with an increased level of biofilm formation (tongue coating and a buildup of deposits around the teeth).

  • The film itself provides increased living space for the kinds of bacteria that cause bad breath.
  • And the buildup of biofilm around teeth places the person at greater risk for developing gum disease.

Both of these factors (discussed further below) are associated with oral malodor.

Smokers tend to have worse oral health status.
While it doesn't have to be the case, studies have shown that smokers tend to have poorer oral home care habits.

In cases where this is true, the person's failure to adequately brush and floss their teeth and clean their tongue, will simply result in increased levels of the types of bacteria that cause bad breath living in their mouth.

Inadequate home care also places the person at greater risk for developing periodontal (gum) disease, a known causative factor for halitosis. (We discuss this issue in greater detail below.)

Section references - Jiun

D) Periodontal (Gum) disease.

Gingivitis and periodontitis (two forms of gum disease) are frequently the underlying cause of a person's breath odor.

Ask any dentist, the smell coming from the mouth of a person with active periodontal disease (an advanced form of gum disease) can be so distinctive that a dentist can correctly diagnose their condition even before they begin their examination.

Collectively, these conditions (or more specifically the bacteria associated with them) are considered to be the second leading cause of bad breath. Quirynen determined that around 15% of halitosis cases were due to gum disease alone, with an additional 24% of cases due to both it and the presence of bacterial coating on the person's tongue.

Section references - Quirynen

Who's at greatest risk for odors associated with gum disease?

  • Gingivitis (inflammation of gum tissue) routinely occurs in all age groups when proper oral home care (brushing and flossing) is not practiced.
  • Periodontitis (inflammation of both gum and bone tissue) is typically more prevalent in "older" age groups (such as age 35 and beyond).

That means that statistically speaking, the older we get the more likely it is that we have a gum condition that will affect our breath quality.

  • It's also considered that breath odors associated with periodontitis (the condition more likely with older adults) are more pronounced than with gingivitis.
  • There's also some evidence that the severity of the gum disease case correlates with odor levels.
  • Dentists sometimes use the BANA test as a method of diagnosing halitosis cases caused by the bacteria that cause gum disease.

Section references - Pham

How gum disease affects your breath.

  • It's both the waste products of the microorganisms that cause gingivitis and periodontitis, and the by-products associated with the inflammation that they create, that produce the volatile sulfur compounds that cause breath malodor.

Healthy vs. diseased gums.

Animation showing periodontal pockets that can harbor bacteria and cause bad breath.

Periodontal disease can result in pocket formation around teeth.

Additional factors with periodontitis.
  • Advanced forms of periodontitis typically result in serious damage to the bone that holds teeth in place.

    As it occurs, deep spaces form between the teeth and gums (termed "periodontal pockets," see illustration), and they provide the ideal anaerobic living environment for the types of bacteria that cause bad breath.

  • Research has found that the amount of odor-causing coating that's present on the tongues of people who have periodontitis is greater than on those who don't (as measured by weight).

    Studies have also determined that the level of volatile sulfur compounds coming from this film is four times greater for people that have periodontal disease than control groups.

Section references - Suzuki, Sanz

The above information suggests that in the case of breath odor associated with gum disease, the most effective cure lies in both resolving the periodontal issue and instituting a regimen of effective tongue cleaning.

Section references - Pham

E) Sinus conditions.

Sinus conditions can cause breath odor problems.

Illustration showing the source of post-nasal drip.

Discharge from the sinuses into the mouth can aggravate breath problems.

1) Postnasal drip.
One of the symptoms of upper respiratory infections and allergies can be a postnasal drip. This discharge falls onto the back portion of a person's tongue, by way of the opening that lies behind the soft palate. (See graphic.)
The discharge itself frequently has a foul taste and smell. What's worse, the bacteria that cause bad breath can use it as a food supply, thus helping them to multiply and produce higher levels of VSC's.
2) Dry mouth.
As an aggravating factor, people who have sinus conditions will often have a stuffed up nose too, and therefore will tend to breathe through their mouth.

The drying effect of doing so tends to create an environment that promotes bad breath (discussed above). Additionally, sinus sufferers are likely to take antihistamines, a type of medicine that's known to cause mouth dryness (see above).

Other upper respiratory infections.

Tonsillitis (an infection of the fleshy pieces of tissue on each side of your throat) or pharyngitis (infection of the throat itself) can be the source of breath odor. As a tip-off that this is the case, you may notice a sore throat, difficulty with swallowing or enlargement of the lymph nodes in your neck or under your jaw.

FYI: Quirynen determined that roughly 4% halitosis cases originated from non-oral sources such as problems associated with the nose, throat, gastrointestinal or respiratory tract infections or systemic diseases.

Section references - Quirynen

F) Medical conditions.

Some medical issues are known to be associated with oral malodor. If a person's breath issues persist after they have consulted with their dentist and have tried the usual simple solutions (that almost always work), then a consultation with their medical doctor may be indicated.

Your doctor will, of course, know what types of conditions to look for. But in general, they will evaluate you for problems associated with your respiratory (pulmonary or bronchial), hepatic (liver), renal (kidney), endocrine (glands that produce hormones) and gastrointestinal (stomach and intestine) systems.

Non-oral causes.

Medical conditions and medications are categorized as "non-oral" causes of bad breath.

And while these factors may be an aggravating or even the fundamental cause of a person's problems, in the majority of cases the origin of breath odors is the oral cavity and it should be evaluated first.

Research suggests that roughly 85 to 90% of all cases of halitosis have an oral origin.

Section references - Danser

G) Foods.

Everyone knows that certain foods and beverages have a reputation for causing bad breath. Some of the most notorious ones are garlic, onions, alcohol and spicy foods in general.

How foods can cause bad breath.

  • When we eat, our digestive system breaks down the food we have consumed into its component molecules. And as it happens, some of them have a very unpleasant odor.
  • As these molecules are created, they are absorbed into the bloodstream so they can be distributed throughout the body as nourishment.
  • As our blood travels through our lungs, some of these molecules are released into them. As a result, as we exhale, they are expelled along with our breath.
"Non-oral" bad breath.

While experiencing this type of condition can be annoying and embarrassing, it's really just "temporary" or "transient" halitosis.

It's classified as another type of non-oral malodor, meaning that the source of the person's breath problems doesn't originate in their mouth.


This type of bad breath will resolve on its own, typically within 48 hours or so, as your body completes the process of breaking down and utilizing, or else excreting, the smelly compounds. You can control this type of malodor simply by avoiding or minimizing your consumption of the offending types of foods.

Illustration of an X-ray of a decayed tooth with an abscess.

Bacteria associated with infected teeth can be the source of breath odors.

H) Dental conditions.

Untreated dental conditions can be the cause of, or a contributor to, a person's breath problems.
  • Active infections, like those associated with abscessed teeth, partially erupted wisdom teeth (pericoronitis) or dental implants (periimplantitis), can all lie at fault.
  • Teeth that have large voids (possibly due to decay or fracture) may trap enough bacteria and debris that they become the source of foul odors.

I) Dentures.

Dentures (complete dentures, full dentures, partial dentures, etc...) can have a big influence on the quality of a person's breath.

How to test for denture breath.

Try this test to see if your dentures might be the source of your breath odors.

  • Remove your dentures and place them in a baggie.
  • Seal the baggie shut and let it sit for about four or five minutes.
  • Now, crack the baggie open and take a whiff.

For better or worse, that's what your breath smells like to others. Use this link for more information about the causes of denture breath and how to remedy it.

Now that you know many of the reasons why you might have bad breath. Our next page explains how to cure it.


 Page references sources: 

Danser MM, et al. Tongue coating and tongue brushing: a literature review.

Jiun IL, et al. Association Between Oral Hygiene Status and Halitosis Among Smokers and Nonsmokers.

Quirynen M, et al. Characteristics of 2000 patients who visited a halitosis clinic.

Pham TAV, et al. Clinical trial of oral malodor treatment in patients with periodontal diseases.

Sanz, M. et al. Fundamentals of Breath Malodour.

Suzuki N, et al. Induction and inhibition of oral malodor.

All reference sources for topic Bad Breath.