Causes and countermeasures for bad breath of concern

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Last updated May 1, 2022


When and what causes bad breath?


Bad breath can give the impression of being unclean.
There are many types of bad breath. In this issue, we will introduce the causes and countermeasures for bad breath that you may be concerned about!

Causes of bad breath

Bad breath Causes

Causes of bad breath include the following

  • Decreased saliva production
  • Food and drinks
  • tobacco
  • Dirt on teeth and tongue
  • Deterioration of artificial teeth and dentures
  • oral disease
  • Diseases of the internal organs and other parts of the body
  • Psychological problems

Decreased saliva production

Halitosis can be caused by decreased saliva production.

When saliva is reduced and the mouth is dry,This is due to the volatilization of methyl mercaptan, hydrogen sulfide, and dimethyl sulfide, three odorants produced by mouth bacteria that make the mouth smell easily.

Decreased saliva production can occur for a variety of reasons, including body mechanisms, changes in female hormone balance, aging, side effects of medications, and physical illness.

In both cases, if the daily brushing of teeth is inadequate, the number of bacteria in the mouth increases and many elements of bad breath are produced, so the bad breath that occurs is stronger.

Body Mechanism

When waking up from sleep, nervousness, or hungeris a body mechanism that causes a decrease in saliva production, resulting in dry mouth and bad breath.

Since bad breath happens to everyone due to the body's mechanisms, it can be quickly remedied by hydration and tooth brushing.

Female Hormone Balance

Menstruation, pregnancy, puberty, and menopause are marked by changes in female hormone production. Although no clear correlation is known,Timing of changes in the balance of female hormones causes a decrease in saliva production and a dry mouth.This is believed to be the cause of halitosis.

adding to one's years

due to ageDecreased saliva production due to muscle weakness around the mouth, decreased body water content, and hormonal imbalanceThis can lead to the development of bad breath.

Side Effects of Medication

Some medications have the side effect of reducing saliva production.People taking the following medications are more likely to have bad breath because their mouths are more likely to dry out.

  • sleep medication
  • antidepressant
  • antiepileptic agent
  • drug to lower blood pressure
  • antihistamine
  • Parkinson's disease drugs, etc.

physical disease

Bad breath caused by physical illness is,One symptom is the odor from the mouth, which causes a decrease in saliva production, and the other is the odor of breath coming from the lungs due to abnormal body metabolism or pus.

Physical ailments that cause halitosis due to decreased saliva production include the following

  • Sjogren's disease
  • diabetes mellitus
  • cerebrovascular disease
  • menopausal disorders

Food and drinks

Foods and drinks that have a strong odor or are easily tangled on the tongue,Odor components on the teeth and tongue can result in bad breath, or bad breath can be caused by activation of oral bacteria and dryness of the mouth.

Breath can also become foul-smelling when food and drink ingredients are broken down in the body and expelled from the body.

Foods that can cause bad breath
Sweet snacks, garlic, chives, leeks, onions, natto, cheese and other dairy products, cruciferous vegetables such as broccoli and cabbage, etc.
Beverages that cause bad breath
Alcohol, coffee, milk, sugary drinks, etc.


The tar in cigarettes is sticky,It sticks to the teeth, tongue, and lungs and produces an odor.Therefore, people who have a smoking habit will smell tar not only from the breath coming out of their mouths, but also from the breath coming out of their noses.

Dirt on teeth and tongue

Dirt on the teeth, tartar, and on the tongue can cause bad breath.

Dirt on the teeth and tongue is a mass of bacteria (plaque) that produces the element of bad breath odor. The greater the amount of dirt, the greater the amount of odorant elements produced, so if skipping brushing becomes a habit, bad breath becomes stronger.

Deterioration of artificial teeth and dentures

Deterioration of artificial teeth or dentures can cause bad breath.

Resin used in dentures has a tendency to absorb odors and may absorb the odor components of bad breath. This can happen after years of use, but if you do not take good care of your dentures on a daily basis, they may start to smell early on.

To prevent odors and prolong denture use, since absorbed odors cannot be removed,It is important to maintain a daily routine with cleaning agents and toothbrushes.

Also, if the gum line does not line up with the covering or if there is a hole in the covering, dirt can accumulate in the gap and cause bad breath.

oral disease

Dental caries, periodontal disease, and oral cancer can cause bad breath.


When decay progresses and the nerve of the tooth is invaded,The nerves in the teeth decay and begin to emit an odor.

periodontal disease

When gum disease occurs, a large amount of an odoriferous substance called methyl mercaptan, which has a strong odor, is produced in the grooves between the teeth and gums (periodontal pockets). The person is often unaware of the smell because he or she has become accustomed to it,The breath is so strong that the odor reaches the person next to you just by opening your mouth and breathing.

oral cancer

He said he had cancer of the tongue and buccal mucosa,Halitosis may occur due to the odor of cancer cells, for example.

Diseases of the internal organs and other parts of the body

Diseases can cause bad breath. The odor differs from halitosis that originates from the mouth,Each disease has its own characteristics.

smelling of rotten meat

  • Sinusitis (sinusitis)
  • sore throat
  • laryngitis
  • Other respiratory and digestive diseases

Both are caused by protein putrefaction (pus) and other factors due to inflammation,It smells like rotten meat.

having a sweet and sour smell

  • diabetes mellitus
  • Impossible diet

Because acetone is produced in the body,It has a sweet and sour odor characteristic of acetone.

Smells like rotten eggs.

  • gastritis
  • stomach ulcer
  • Duodenal ulcer, etc.

Food and drinks ferment due to indigestion,Hydrogen sulfide is produced and becomes halitosis.

smack of rotten fish

  • Trimethylaminuria (fish odor)
  • impairment of liver function

Trimethylamine is a component that is broken down in the liver. If trimethylamineuria or liver dysfunction is present, the liver is unable to break down trimethylamine,The odor of trimethylamine may be mixed with halitosis when it is expelled from the body.

ammonia odour

  • uremia
  • Decreased renal function
  • Decreased liver function

When ammonia cannot be broken down in the body,The odor of ammonia may be mixed with halitosis.

Psychological problems

Stress causes dry mouth and bad breath, and too much concern about bad breath image,They may assume that they have bad breath even though they do not.

How to prevent bad breath

Prevention of bad breath

To prevent bad breath,It is important to prevent two major causes of bad breath: stained teeth and tongue and dry mouth.

These two are the basics, and other measures should be taken according to the other causes. If you are not sure of the cause, we recommend that you seek advice from your dentist.

  • toothpaste
  • wet one's whistle
  • No Smoking!
  • See a dentist.
  • see a doctor


Brushing teeth is,Very effective in reducing the activity of bacteria that create bad breath odor in the mouthIt is. If you do not brush your teeth properly, dirt builds up on your teeth and tongue, which can also cause bad breath due to tooth decay and gum disease.

Denture wearers should clean their dentures after meals with a cleaning agent or denture brush, and clean any stains on the tongue by gently scrubbing with a toothbrush.

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wet one's whistle

One of the major causes of bad breath is dry mouth.If you are concerned about dry mouth, use the following methods to keep your mouth moist.

  • Chewing gum to stimulate saliva production
  • Salivary gland massage to stimulate saliva production
  • Stay hydrated (sugary drinks, coffee, and alcohol do not dry out the mouth).

No Smoking!

Tobacco causes bad breath.Since it is caused by smoking itself, it is recommended to quit smoking if possible.

If it is difficult to do so, brush your teeth after smoking and get regular dental cleanings to ensure that you are taking good care of your teeth.

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See a dentist.

By seeing a dentist, the cause of bad breath can be removed and prevented.

  • Dental cleanings remove tartar that causes bad breath.
  • Checking and rebuilding of coverings and dentures
  • Have any cavities or gum disease treated.

see a doctor

If bad breath is caused by a physical illness,You need to see a medical doctor to treat the disease.

If the medication is decreasing saliva production and causing bad breath, you should consult your doctor to see if the type of medication can be changed.

There are many causes of bad breath.

Bad breath Causes

There are many causes of bad breath. If you have bad breath, there is a problem with your daily brushing or your mouth, but don't overlook it because it is a sign that something is amiss with your whole body.

365dentistprovides you with useful information about your mouth! There is also an open chat where you can discuss your oral problems with Dr. Yukiko, our dentist!

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Graduated from Nagasaki University School of Dentistry, ~2018 Kyushu Medical Center, 2018-present Working at a dental clinic in Tokyo

UyRZkXPjQvAn5BK9ai6vfhAEgYGCePrS3Id158EZKuev 2TIlSXaZPkxY9dJ 3vCTCm7hqIEw6AzmlpdiuMD8H 9aD01UftplKrgMtn7dmYeSupervisor: Dentist/Naomi

After completing clinical training, worked in cosmetic dentistry in Tokyo. Currently a dentist and dental writer.


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