Halitosis is the medical term for bad breath. It is estimated that about 10-15% of halitosis may be due to disorders of the sinuses, nose, throat, lungs, esophagus, or stomach, while the remaining cases of halitosis arise from within the mouth itself. Halitosis may be a symptom of an underlying medical condition, including liver failure, though this is rare. Treatment for halitosis is largely determined by the underlying cause. Thoroughly cleaning the tongue and teeth, along with flossing and using mouthwash, may eliminate halitosis. Treating any underlying conditions may also help reduce or eliminate halitosis. Halitosis becomes more common as people age and is the third most common reason people seek professional dental care.


The most common cause of intra-oral halitosis, or halitosis that is produced within the mouth itself, is biofilm that may be present in the mouth, especially on the back of the tongue, due to inadequate oral hygiene. As proteins break down in these biofilms, they produce foul-smelling gases which emanate from the oral cavity. Intra-oral halitosis may also be cause by oral lesions caused by certain viral infections. Halitosis may be exacerbated by eating very pungent-smelling foods, consuming alcohol, and smoking, and it is often worse in the morning. Halitosis may come and go, or it may be persistent or chronic. It is estimated that about 25% of the population suffers from chronic halitosis.


The very back of the tongue is the most common intra-oral source for halitosis. It is difficult to clean, and its location and shape create an excellent breeding ground for bacteria, which can combine with food debris and postnasal drip and cause foul odors. Halitosis may also arise from the areas between the teeth and the gums, known as gingival crevices, and is especially common in people with advanced periodontal disease. The larger these gingival crevices are, the more likely they are to harbor infection, which creates malodor. Less common causes of intra-oral halitosis include tooth decay, recent extractions, food debris that is trapped between teeth or under ill-fitting dental fillings, infections and ulcerations in the mouth, dietary changes, smoking, alcohol consumption, stress or anxiety, certain medications, and hormone fluctuations.


Halitosis that does not arise from within the mouth may be produced by a number of possible causes. Sinus infection of the presence of foreign bodies in the nose may cause halitosis, for example, and the presence of infection in the tonsils may also lead to halitosis. Halitosis may also be produced by an improperly operating esophageal valve, either due to gastroesophageal reflux disease or a hiatal hernia allowing acids in the esophagus to escape into the mouth. Fistulas between the stomach and esophagus can also cause bad breath, though these also create more serious symptoms that must be prioritized and treated. Other systemic medical conditions that cause bad breath also have more serious symptoms and are uncommon; these include respiratory tract infections, kidney infections, cancers, diabetes, liver failure, and certain other rare conditions.


It is difficult to diagnose one’s own halitosis, as we are often conditioned to the smells our bodies produce, but dentists can diagnose halitosis and also make any necessary referrals when and if halitosis seems related to any larger systemic issues. Dentists can also recommend halitosis-management techniques and prescribe any recommended antibacterial products. If halitosis is caused by smoking, dentists can work with patients on smoking-cessation methods, and if halitosis is caused by gum disease or cavities, dentists will treat these underlying issues.