Image by Engin_Akyurt from Pixabay

Feb 22, 2019 | Health Matters

Causes of Bad Breath

Bad breath is a common health problem which greatly affects the day to day activities of so many people. The offensive odour from the mouth is unpleasant to those who come in close contact with bad breathers.

The problem will be doubled by psychological trauma leading to depression. The sufferers from this problem will be isolated from society. This can even lead to marital disharmony.

Speaking all human beings are bad breathers. The oral cavity contains millions of anaerobic bacteria like Fusobacterium and actinomyces which acts on the protein of food materials and putrifies them.

This process results in the formation of offensive gases like hydrogen sulphide, methyl mercaptan, cadaverine, skatol, putrescine etc causing bad odour. If oral hygiene is not maintained properly all will suffer from bad breath.

Most of us control this by regular brushing, tongue cleaning and gargling. Even after maintaining cleanliness in the mouth some individuals suffer from offensive smell due to various causes which have to be diagnosed and treated properly.

Some of the causes of bad breath are as follow:

Poor Oral Hygiene

If oral hygiene is not maintained properly the mouth becomes the seat for millions of bacteria which produce offensive gases by degrading the food debris. Bad breath is severe in those who do not brush their teeth regularly and clean their mouth after every food. Snacks taken in between meals can also produce bad breath because of improper cleaning.

Bad breath is common in almost all people in the morning on waking. During sleep, there is less production of saliva. Saliva has got some antibacterial properties which help to keep the mouth clean. Saliva contains oxygen molecules which are needed to make oral cavity aerobic. So the reduction in its quantity during sleep makes a favourable condition for anaerobic bacteria.

Food Habits

The main cause of the bad smell is due to the degradation of protein by the bacteria and hence all food products rich in protein favours bad breath. Meat, fish, milk products, eggs, cakes, nuts and pear can cause bad breath. Some food articles can produce a particular type of smell which may be unpleasant.

Raw onion can produce typical bad smell. It is said that an apple a day keeps the doctor away, a raw onion a day keeps everybody away. Eating groundnuts can also produce bad smell. However, if proper cleaning is done smell can be reduced irrespective of the nature of food. Irregularity in the timing of food can also produce bad breath. Small food articles taken in between the meals can also produce bad smell.


There is the formation of a thin sticky coating called biofilm on the tongue and oral mucosa. This coating is thick on the posterior aspect of the tongue where millions of gram-negative bacteriae are seen. The thick coating on the tongue is always associated with bad breath. Even a thin biofilm can make anaerobic condition favourable for bacterial proliferation.

Gum Retraction

When the gums retract from the teeth a gap is developed which will lodge food particles and cause bad breath.

Dental Plaques & Tartar Deposits

Plaques and tartar are deposited mainly in the gaps between the teeth and gum. This will provide shelter for the food debris and bacteria causing bad breath.


Dental Caries

This is a destructive process causing decalcification with the destruction of enamel and dentine resulting in cavitation of the tooth. These are produced mainly by the lactobacilli. Food particles are deposited inside these cavities and are putrified by the anaerobic bacteria producing bad smell.

Normal brushing will not remove the food debris easily and hence they are putrified completely. Caries is common in schoolgoing children and in those who do not maintain proper oral hygiene. Calcium and vitamin deficiency can also predispose caries.


Gum is a mucus membrane with supporting connective tissue covering the tooth-bearing borders of the jaw. The main function of gum is protection. Gingivitis is the inflammation of the gum. Due to various causes gum tissue get infected resulting in swelling, pain and discharge.

If the condition becomes worse the infection spread towards periodontal area leading to continuous discharge called pyorrhoea. Some times the infection goes deep producing alveolar abscess with discharge of pus. Infection can even reach the bone causing osteomyelitis. All these conditions can produce an offensive smell.

Ulcerative Lesions & Coatings

Almost all ulcerative lesions of the mouth are associated with bad breath. These lesions may be caused by bacteria, viruses, food allergies or due to autoimmune disorders. Aphthous ulcer is the commonest among ulcerative lesions. Others are herpes, fungal infections, Vincent’s angina, infectious mononucleosis, scarlet fever, diphtheria, drug reactions, etc. Cancerous ulcers produce severe bad breath.

All fungal infections produce a white coating(candidiasis). Leucoplakia is a white thick patch on the mucous membrane of the mouth & tongue. It is considered a precancerous condition. Offensive breath is associated with these conditions.

Diseases of the salivary glands

Saliva is very useful to supply oxygen to all parts of the oral cavity. Even a thin film of coating called biofilm can provide an anaerobic condition in the mouth. Saliva can wet these layers and make an aerobic condition which is unfavourable for the bacteria. Any condition which reduces the production of saliva can increase bacterial activity.

Some times the salivary duct is obstructed by stones or tumours. Cancer of the salivary gland is associated with an offensive odour. In suppurative parotitis, purulent discharge into the mouth causes bad breath.


Tonsils are a pair of lymphoid tissue situated in the lateral wall of oropharynx. Inflammation of the tonsil is called tonsillitis. Bad breath is seen in both acute and chronic tonsillitis. Quinsy or peritonsillar abscess can also produce bad breath.

Tonsillar plaques & tonsillar fluid

If bad breath persists even after maintaining proper oral hygiene there is a possibility of this condition. Serous fluid secreted from the folds of the tonsil is very offensive. Some patients complain that they hawk some cheesy materials from the throat; which are very offensive. These are formed inside the tonsillar crypts which contain thousands of bacteriae. In such conditions, tonsillectomy gives noticeable relief from bad breath.

Pharyngitis & pharyngeal abscess

The pharynx is a fibromuscular tube which forms the upper part of the digestive & respiratory tract. Inflammation of the pharynx is called pharyngitis, caused mainly by bacteria and viruses. Bad breath is present in pharyngitis along with other signs like cough and throat irritation. Abscesses in the wall of the pharynx can also produce an offensive discharge of pus into the throat.


Denture users may complain about bad smell due to the lodgement of small food debris in between. Proper brushing may not be possible in denture users especially fixed dentures.


Tobacco chewing is associated with bad breath. The smell of tobacco itself is unpleasant for others. Tobacco can irritate the mucous membrane and cause ulcers and coatings. Gingivitis and pyorrhoea are common in tobacco chewers.

Tartar is deposited on the teeth mainly near the gums. Tobacco chewers get gastric acidity with eructations. All these cause the offensive smell.


Smokers always have a bad smell. It can also produce lesions in the mouth & lungs causing bad breath. Smoking increases carbon dioxide in the oral cavity & reduces oxygen level, causing a favourable condition for bacteria. Smoking reduces appetite & thirst hence the acid peptic disease is common in chain smokers.

Lesions in the nose & ear

Bad breath is occasionally seen in sinusitis (infection of para nasal sinuses). In case of post nasal dripping bad breath is common due to the presence of protein in the discharges. These proteins are degraded by the bacteria. Infection in the middle ear with a discharge of pus into the throat through the eustachian tube (passage from the middle ear to the throat)can also cause an offensive odour.

Chronic rhinitis (infection of the mucous membrane of the nose) and foreign bodies in the nose can also produce bad smell in the expired air.


Bad breath is common in almost all fevers. Even an acute fever can produce bad breath. Severe bad breath is seen in typhoid. Other infectious diseases like Tuberculosis, AIDS etc produce bad smell.

Diabetes mellitus

Mostly all diabetic patients suffer from bad breath. Coated tongue, ulcers & coatings in the mouth, the increased sugar level in tissues etc are responsible for bad breath.

Bacterial growth in diabetic patient is very faster than non-diabetic individuals.

Fasting & dehydration

Dry mouth favours bacterial activity. So any condition which produces dryness in the mouth makes the breath offensive. Even though the food particles are known to produce bad breath, fasting can also produce the same.

Production of saliva is also reduced during fasting. Chewing and swallowing also helps to keep the mouth clean.

Bedridden patients

Bedridden patients suffer from offensive breath due to a thick coating on the tongue. water intake is also limited in these patients. Regurgitation of food aggravates the condition. Since they talk less aeration in the oral cavity is reduced which favours anaerobic bacteria to become active.

Diseases of stomach & oesophagus

Eructation of gas and food produce an unpleasant smell. Abnormality in the function of the lower sphincter can allow the food to regurgitate upwards causing bad breath. Bad breath is also common in gastritis, gastric ulcer and cancer of the stomach.

Intestinal diseases

Bad breath is common in patients suffering from ulcerative lesions of intestine like ulcerative colitis. Other diseases are malabsorption syndrome intestinal tuberculosis, peritonitis etc.

Diseases of lungs

Lung diseases like pneumonia, lung abscess, chronic bronchitis, bronchiectasis, tuberculosis, lung cancer etc can produce bad odour during expiration.

Liver disorders

Liver diseases like hepatitis, cirrhosis, can cause bad breath. Gall bladder diseases with vomiting also cause an unpleasant odour.

Psychiatric patients

Bad breath is common in psychotic patients due to poor hygiene, irregular food habits, less water intake, etc.

Somatisation disorder

This is a psychiatric disorder characterised by the presence of a physical symptom that suggests a medical illness. These patients come with physical complaints like pain, nausea difficult respiration, bad smell etc.

This condition is diagnosed after a detailed examination of the patient with all investigations. Since this is a psychiatric disorder it has to be managed with a psychological approach.


It's $0.99 from your spare change to give credits to our writers and providers that bring this awesome resource to you. Your little change makes all the difference. Your donation shows appreciation.


Subscribe For Updates & Offers

Receive a notification on news and updates on all special offers.