From a medical point of view, it is not a disease but rather an important symptom resulting from pathological processes in the oral cavity or, in rarer cases, from systemic disorders. The problem can cause significant psychological discomfort and may lead to reduced social activity.
Direct cause of the characteristic odour is the presence of volatile sulphur compounds (VSCs), mainly hydrogen sulphide, methyl mercaptan, and dimethyl sulphide. These compounds are by-products of metabolism of anaerobic bacteria, which thrive in environment with low oxygen. Their highest concentration is found in the coating on the tongue, in periodontal pockets, and around defective dental restorations.
In this article, we explain how to effectively eliminate halitosis.
Bacterial causes of dental problems
Most cases of halitosis originate from intraoral conditions, where bacterial biofilm plays a key role. Dental plaque, which can mineralise into tartar, creates a porous structure that provides an ideal environment for bacterial colonies that cannot be removed with standard oral hygiene. Anatomy of the dorsal surface of the tongue is equally important. Its numerous grooves and papillae form the largest reservoir of debris and microorganisms in the oral cavity. Advanced tooth decay or periodontal disease further aggravate the problem
by creating pathological periodontal pockets. In these ecological niches, where oxygen supply is limited, anaerobic bacteria multiply freely, producing large amounts of volatile sulphur compounds directly in the exhaled air.
Extra-oral halitosis and systemic disorders
When dental diagnostics rule out local causes, a possible cause of systemic diseases and hydration levels should be considered. Xerostomia (dry mouth), or reduced saliva production, significantly lowers natural self-cleansing capacity of the oral cavity and disrupts pH balance, accelerating putrefactive processes. Upper respiratory tract diseases, including chronic sinusitis, may also play a role. Mucus draining down the back of the throat can become a breeding ground for bacteria. Another common cause of strong odour is the presence of tonsil stones, which are calcified deposits trapped in the tonsillar crypts.
Differential diagnosis also includes gastro-oesophageal reflux disease (GORD) and gastrointestinal infections, which may allow digestive gases to enter oral cavity. Bad breath can also serve as a diagnostic marker of metabolic diseases. For example, an acetone smell may indicate diabetic ketoacidosis in patients with diabetes and ammonia-like smell (uremic fetor) may suggest progressive kidney failure, requiring immediate medical attention.
Impact of diet and daily habits on fresh breath
Daily dietary choices and lifestyle habits have a direct impact on the oral cavity. One of the most important factors is correct hydration. Regular water intake helps mechanically rinse away food debris and bacteria, but most importantly stimulates saliva production. Saliva acts as a natural cleansing solution that neutralises acids and inhibits the growth of microorganisms responsible for halitosis. When natural saliva production is reduced, it may be helpful to use products containing xylitol, such as sugar-free chewing gum. Xylitol stimulates saliva production and limits the growth of cavity-causing bacteria, helping maintain oral balance.
Diet composition also plays an important role. Hard, fibrous foods, such as raw carrots and apples, help mechanically clean teeth during chewing. On the other hand, certain foods naturally contain sulphur compounds, including garlic and onions. In these cases, odour is created differently: these compounds are absorbed into the bloodstream and later expelled through the lungs during exhalation, which means that brushing teeth alone after eating may not eliminate the smell.
Substances such as tobacco, coffee, and alcohol can significantly worsen breath quality.
Smoking causes plaque to accumulate on mucous membranes and teeth while reducing oxygen supply, which promotes anaerobic bacteria growth. Additionally, tobacco smoke and alcohol dry out the oral mucosa. Chronic dryness accelerates putrefactive processes because the protective barrier provided by saliva is reduced.
Replacing coffee and alcohol with water or unsweetened herbal infusions helps maintain proper moisture levels and fresher breath for longer.
When does bad breath require medical consultation?
In some patients, halitosis persists despite strict oral hygiene. In such cases, the unpleasant odour should no longer be treated as merely an aesthetic issue but rather as a potential diagnostic indicator. The first step should always be a visit to a dentist, who will assess the condition of the gums and teeth and rule out hidden sources of tooth decay. If the dentist confirms that the oral cavity is healthy, but the problem persists, further diagnostics may include internal medicine, ENT, or gastroenterology examinations.
Certain accompanying symptoms should not be ignored, including recurrent bleeding gums, pain when swallowing, chronic hoarseness, and sensation of a foreign body in the throat. Halitosis accompanied by upper abdominal pain, heartburn, or unexplained weight loss is also concerning. In such cases, a doctor may recommend gastroscopy to rule out oesophageal or stomach diseases, including Helicobacter pylori infection, which is often associated with characteristic bad breath.
The type of odour itself may also indicate specific metabolic disorders. For example, smell resembling rotten apples or acetone may signal uncontrolled diabetes and ketoacidosis, ammonia-like smell may indicate kidney failure, and a musty or “mousy” smell may be associated with liver dysfunction. In these cases, halitosis is only a secondary symptom of internal organ dysfunction.
Diagnosing halitosis - which doctor should I see?
Dentist
Dentist is the first specialist to consult. They assess teeth for cavities, leaking fillings, and tartar buildup. If symptoms include bleeding gums or tooth mobility, a periodontist review (a specialist in gum and periodontal diseases) may be required. General practitioner (GP / internal diseases doctor)
If dental causes are excluded, the next step is a visit to a GP. The doctor will take a medical history and order basic laboratory tests such as full blood count, glucose levels, and kidney and liver function tests. GP coordinates further diagnostic and referrals.
ENT specialist (otolaryngologist)
An ENT consultation is necessary when chronic infections of the upper respiratory tract are suspected. The doctor evaluates the condition of the sinuses and tonsils. A common cause of halitosis is tonsil stones, which may require professional removal or, in some cases, surgery.
Gastroenterologist
Gastroenterologist should be consulted if halitosis is accompanied by digestive symptoms such as heartburn, belching, upper abdominal pain, or nausea. This specialist diagnoses conditions such as gastro-oesophageal reflux disease (GORD), oesophageal diverticula, and Helicobacter pylori infection. They all may have impact on bad breath.
Diabetologist or nephrologist
In rarer cases where breath has a distinctive odour (such as acetone or ammonia), consultation with a diabetologist or nephrologist may be necessary to rule out diabetes complications or kidney disease.
Effective diagnosis and treatment of halitosis at a Polish clinic in London
Treatment of halitosis at our medical and dental practice in London focuses on identification of bacterial niches and the use of modern professional hygiene procedures. We use advanced methods for removing mineralised dental deposits, which is the foundation of reducing volatile sulphur compound emissions. Our team develops individual treatment plans, combining professional dental procedures with education on optimal home oral hygiene and the selection of appropriate therapeutic products. Book your consultation, during which our specialists will recommend solutions that effectively restore fresh breath and oral health.
