Is there a Connection Between Bad breath and Systemic Disease?

Bad breath or ‘halitosis’ is an embarrassing situation for anyone. It is a pretty common condition which affects almost one-third of the general population.

Most of us don’t even realize that we have bad breath till someone else points it out. People, who have bad breath, live in constant social anxiety. In most cases, bad breath is temporary, but in some cases, it can last for a long time.


Halitosis or bad breath may be a signal to an underlying systemic disease that you may be suffering. Bad breath is the third most common cause of seeking a dentist, after tooth decay and gum diseases. (1)

Continue reading to find out what is your bad breath telling about your body.

What is halitosis?

Bad breath, also known as halitosis, is a symptom in which a noticeably unpleasant breath odor is present. It is associated with depression and symptoms of obsessive-compulsive disorder.

Simple home remedies and lifestyle changes can help remove bad breath. It is transient, but if it persists for a long time, it is advisable to consult a doctor to check for any underlying causes.

What causes bad breath?

There are many potential causes of bad breath, certain foods, habits and medical conditions being the most common reasons.

Bad breath or ‘halitosis’ is mainly caused by excessive amounts of volatile sulfur compounds (VSC) being produced by the bacteria in the mouth.

The amount of VSC can vary significantly during the day and is influenced by factors such as eating, drinking, oral hygiene, sleeping and the effect these activities may have on the salivary flow.

Some potential causes of bad breath are –

1. Tobacco

Both tobacco chewing and smoking give a distinct odor to your breath that is not pleasant. Tobacco products can also cause gum diseases which again contribute to bad breath. (2)

2. Certain types of foods

Some foods like onion or garlic can cause bad breath, even after it has been digested. After you digest these foods, the breakdown products enter your bloodstream, reach the lungs and affect your breath.

3. Dry mouth

Saliva keeps your mouth clean and maintains the balance between good and bad bacteria. Less salivary flow in dry mouth leads to a microbial build-up in your mouth which causes halitosis.

4. Poor oral hygiene

The food particles stuck between your teeth act as a perfect breeding ground for the bacteria in your mouth to produce volatile sulfur compounds. Improper brushing habits can cause gum and periodontal diseases which can, in turn, cause bad breath. (3)

5. Crash diets

Some crash diets can cause halitosis due to the production of a compound known as a ketone. It is produced through the breakdown of fats, which happens if you are on a low- carbohydrate diet.

6. Medications

Certain drugs and medicines cause bad breath indirectly by creating dry mouth. Also some drugs breakdown and release chemicals in your breath that produces a bad odor. (4)

7. Mouth, nose and throat conditions

Bad breath can stem from small stones that form in the tonsils and are covered in bacteria. Chronic infections in the nose, sinus or throat contribute to post-nasal drip, which can cause bad breath.

8. Systemic diseases

Some disease like cancer and metabolic conditions like GERD can cause halitosis because of the chemicals they produce and release in your breath.

9. Infections in your mouth

Chronic oral diseases like tooth decay, gingivitis, etc. cause halitosis due to increased levels of bacteria in your mouth.

How to diagnose bad breath?

In most cases, a dentist can diagnose halitosis by merely smelling the breath of the patient and then, rate the odor on a six-point intensity scale. The dentist can also scrape the back of your tongue and smell the scrapings to determine if you have halitosis.

There are some more sophisticated detectors also present, which can determine bad breath more precisely:

  • Halimeter – detects low levels of sulfur.
  • Gas chromatography – measures amounts of volatile sulfur compounds
  • BANA test – measures levels of a specific enzyme produced by halitosis-causing bacteria.
  • Beta-galactosidase test – measures levels of beta-galactosidase which correlates with bad mouth odor.

Bad breath and systemic disease connection

In almost all cases, bad breath can be traced back to your mouth. It is also transient and resolves on its own. But in cases where bad breath lingers for a longer time, it can be related to an underlying systemic disease.

Cheesy smellNasal or sinus infection
Fruity smell Uncontrolled diabetes
Fishy smellKidney disease
Acidic smellAsthma or Cystic Fibrosis
Ammonia smellKidney problems
Sweet, musty odorLiver cirrhosis
Fecal OdorBowel obstruction

Your dentist can identify this oral-systemic link to recognize the potential problem elsewhere in your body. These are the possible different mouth odors related to systemic diseases. Let’s see how different systemic diseases affect your breath –

1. Tonsils and bad breath

Infections in your tonsils (tonsillitis) or tonsil stones may cause your bad breath. Halitosis can occur in acute, chronic or recurrent tonsillitis. The bacteria responsible for tonsil infection may also be causing your bad breath.  (5)

Tonsil stones contain compressed sulfur compounds, mucus, and bacteria, which contributes directly to bad breath.

2. Sinus and bad breath

Sinusitis is an inflammation of your nasal sinuses. It is related to growth and build-up of microbes in your nasal cavity, resulting in bad breath. The symptoms of sinusitis vary according to its severity and which sinus is involved and go alongside bad breath.

A nasal polyp is a soft, jelly-like overgrowth of the sinus lining. It blocks your airway and causes bad breath due to the run-over of post-nasal drip.

Sinusitis, nasal polyps and post-nasal drip can all cause halitosis as it encourages the build-up of microbes, foreign objects, and metabolites that result in bad breath.

3. Lungs and bad breath

Lung infections and conditions like bronchitis, pulmonary abscess, tuberculosis, etc. can cause bad breath due to increased mucus production.

People with asthma suffer from dry mouth, which contributes directly to bad breath.

Patients with cystic fibrosis have swollen, thick and immobile mucus which leads to sinus blockage, causing halitosis.

4. Gut and bad breath

There are many conditions of the digestive system which can cause halitosis. Any situation which allows air from the stomach to enter your mouth through the esophagus can result in bad breath. It is generally a sign of imbalance in the digestive system.

5. Metabolic conditions and bad breath

Low-carbohydrate or ketogenic diets force your body to burn fats instead of carbohydrates for energy. It produces a compound called ketone, which enters your breath and gives it an odd fruity or acetone breath.

Also, regular fasting or skipping meals can cause dry mouth, which in turn causes halitosis.

6. Diabetes and bad breath

There is insufficient production of insulin in diabetes, which makes the body burn fat instead of carbohydrates, leading to the production of ketones. It results in an acetone odor on your breath.  (6)

Also, people with diabetes suffer from chronic kidney failure, which makes your breath smell ‘fishy’ or like ammonia.

7. Liver and bad breath

In Frank liver failure, the body tries to excrete the by-products of sulfur-containing amino acids breakdown through the lungs. It gives a sweet smelling, musty odor on your breath.

Liver cirrhosis can give an odor of spoiled blood or rotting eggs to your breath.

It can be used as a potential diagnostic tool for detecting liver problems.

8. Genetic disease and bad breath

An undiagnosed genetic disorder, TMAU or trimethylaminuria, affects the body’s ability to breakdown choline. It causes body and breath odor which resembles rotten eggs, garbage or urine.

This smelly odor is excreted via sweat, urine, saliva, blood, and air exhaled through mouth and nostrils. (7)

9. Menstruation and bad breath

It has been noted that during menstruation, an average female has more amounts of volatile sulfur compounds on their breath, regardless of the level of bacteria. Hormonal changes during your period can cause temporary halitosis.

10. Halitophobia

Almost all of us are concerned about how our breath smells. But for some people, this concern turns into a phobia. Although this ‘halitophobia’ affects less than 1% of the adult population, it can have a serious effect on a person’s personal life and cause:

  • Social anxiety
  • Withdrawal from social situations
  • Fear of speaking, even not speaking at all
  • Anxiety about physical intimacy
  • Constant gum chewing/ mint sucking
  • Refusal to eat certain foods
  • Living in fear of offending people with bad breath
  • Extensive teeth brushing

How to prevent bad breath?

Halitosis is easily preventable with some simple steps like –

  • Practice good oral hygiene – Remember to brush twice a day and floss regularly after every meal. Don’t forget to clean your tongue too as it can carry the maximum amount of bacteria that can cause halitosis. (8)
  • Visit your dentist regularly – It is advisable to visit your dentist every six months. They can perform an oral exam to check for any cavities. You can also get a professional cleaning done, which can eliminate most of the causes of bad breath.
  • Stop smoking or chewing tobacco – if you smoke or chew any of the tobacco products, you should stop immediately. It will prevent the distinct ‘tobacco’ odor from entering your breath. It will also prevent gum and periodontal diseases, which can cause bad breath.
  • Stay hydrated and Chew gum – Drinking lots of water helps to keep your mouth moist and clean, which prevents dry mouth. Chewing sugarless gum or sucking on sugarless candy stimulates salivary flow which prevents dry mouth, and in turn, prevents bad breath.
  • If you are a denture wearer, make sure to keep your denture clean at all times. It removes food debris stuck in your denture and also prevents microbial build-up, which can result in bad mouth odor.
  • Avoid onion, garlic or spicy foods in your diet. Reduce sugar and alcohol consumption. Try to include rough and fibrous foods in your diet, which keeps the tongue clean.
  • Use an antiseptic mouthwash in your oral hygiene routine. It eliminates the bacteria responsible for bad odor on your breath. (9)


Halitosis is transient and goes away when the cause is treated. However, your bad breath may be a signal to some underlying systemic disease.

A number of conditions like diabetes and chronic kidney failure can give rise to abnormal odors in your breath.

Tooth brushing, eating and chewing gum, tongue-cleaning and use of an anti-microbial mouthwash are effective in controlling and preventing oral bad breath to an acceptable level.


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