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Bad Breath Can Be A Sign Of Several Health Problems; Here Are The Possible Causes

Bad breath is harmless, but it can be associated with certain health conditions that need to be addressed. 

Tenzin Chodon
Written by: Tenzin ChodonUpdated at: May 18, 2023 14:17 IST
Bad Breath Can Be A Sign Of Several Health Problems; Here Are The Possible Causes

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Did you brush? A remark people often make when they smell bad breath. But is brushing the only reason for a foul-smelling breath? Not really. Speaking with Only My Health, Dr Aravind M.S (M.D.S), Reader/Associate Professor - Oral Medicine and Maxillofacial Radiology, Amrita School of Dentistry, Kochi, explained how bad breath can be caused by several factors ranging from lifestyle choices to medical conditions. Let’s take a look at some of the common causes. 

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Common Causes Of Bad Breath

Lifestyle factors can contribute to foul-smelling breath. These include:

Poor oral hygiene

Inadequate brushing, flossing, and tongue cleaning can lead to the accumulation of food particles and bacteria in the mouth, causing bad breath, says Dr Aravind.

Certain foods and beverages

Foods such as onions, garlic, spices, and strong cheeses can leave a lingering odour in the mouth. Additionally, consuming beverages like coffee can contribute to bad breath.

Alcohol Consumption

According to Dr Aravind, alcoholic beverages can contribute to bad breath, as alcohol itself has a drying effect on the mouth. Additionally, some alcoholic beverages have strong odours that can linger on the breath.

Smoking and tobacco products

Tobacco products not only cause their own distinct odour but also dry out the mouth and increase the risk of gum disease, which can lead to bad breath. 

Dieting and Fasting

Restrictive diets and fasting can lead to the production of ketones in the body, which can cause bad breath. This is commonly known as "diet breath" or "ketosis breath”.


Dr Aravind urges increased water intake as dehydration can contribute to dry mouth and a decrease in saliva production, resulting in bad breath.


Some medications, such as certain antihistamines, antidepressants, and diuretics, can cause dry mouth as a side effect. This can contribute to the development of bad breath.


Stress can affect the normal functioning of the body, including saliva production. Increased stress levels may result in dry mouth and the onset or exacerbation of bad breath.

Mouth breathing

Breathing through the mouth instead of the nose can cause dry mouth and reduce saliva flow, leading to bad breath.

Poorly-fitted dental appliances

Ill-fitting dentures, dental braces, or other dental appliances can trap food particles and bacteria, leading to an unpleasant odour in the mouth.

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Medical Conditions That Can Contribute To Bad Breath

Certain medications can also lead to bad breath. These include:

Respiratory Infections

According to Dr Aravind, infections in the respiratory tract, such as sinusitis, bronchitis, and pneumonia, can cause bad breath due to the release of odorous substances when exhaling.

Tonsil Stones

Tonsil stones, also known as tonsilloliths, are calcified deposits that form in the crevices of the tonsils. These stones can harbour bacteria and emit a foul odour.

Dry mouth (Xerostomia)

Dry mouth can be caused by various factors, including medication side effects, salivary gland problems, or breathing through the mouth. Reduced saliva flow allows bacteria to multiply, causing bad breath.

Bacterial growth on the tongue

Dr Aravind said, “The surface of the tongue can harbour bacteria, debris, and dead cells, resulting in a foul odour. This is especially true toward the back of the tongue.”

Oral infections

Gum disease (periodontal disease) and tooth decay can create an environment where bacteria thrive, leading to bad breath. Infected tonsils or mouth sores can also contribute to foul-smelling breath.

Gastrointestinal Issues

Certain gastrointestinal conditions, such as acid reflux (Gastroesophageal Reflux Disease (GERD)), chronic gastritis, and bowel disorders, can cause bad breath. The odours from the stomach can travel up the oesophagus and contribute to halitosis, said Dr Aravind. 


Uncontrolled diabetes can result in a fruity or sweet odour on the breath, often described as "acetone breath”. This is due to the breakdown of substances called ketones.

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Liver Disease

Liver diseases, such as cirrhosis or hepatitis, can lead to a buildup of substances in the body that cause a distinct odour on the breath.

Kidney Disease

People with advanced kidney disease may experience a fishy or ammonia-like odour on their breath due to the body's inability to properly filter waste products conditions like uremic stomatitis when levels of urea increase in the body.

Respiratory conditions

Chronic conditions like chronic obstructive pulmonary disease (COPD) and lung abscesses can cause persistent bad breath due to the respiratory system's compromised function.

Oral Cancer

Although relatively rare, oral cancer can lead to bad breath too, particularly if it affects the throat or oral cavity.


Bad breath is harmless in most cases. However, knowing what is causing it is important. If your breath smells foul for a consistent period of time, then you must visit a healthcare professional to know the cause and get appropriate treatment.