What Is It, Causes, Symptoms, and More

Author: Lily Guo

Editors: Alyssa Haag, Emily Miao, PharmD, Kelsey LaFayette, DNP

Illustrator: Jessica Reynolds, MS

What is halitosis?

Halitosis, commonly known as bad breath, is characterized by oral malodor exceeding socially acceptable levels. It is a highly prevalent condition, potentially affecting up to 30% of the population, and impacting quality of life and personal relationships. Three main types of halitosis include physiologic halitosis (i.e., “morning breath”); pathologic halitosis, arising from a specific identifiable cause; and pseudo-halitosis, which is the perception of bad breath without objective evidence.

Oral cavity.

What causes halitosis?

The cause of halitosis depends on the specific subtype. Physiologic halitosis is the most common type and is generally due to anaerobic bacteria that are part of the normal oral flora. The primary culprits are gram-negative anaerobes (e.g., Bacteroides forsythus, Porphyromonas gingivalis, Prevotella intermedia) that produce malodorous substances, including volatile sulfur compounds (e.g., hydrogen sulfide, methyl mercaptan, and dimethyl sulfide). Physiologic halitosis is worse in the morning due to low saliva flow, as saliva plays a role in cleaning the oral cavity and has antibacterial properties. Therefore, halitosis can be exacerbated by breathing through the mouth, causing dry mouth. Also implicated in physiologic halitosis are the tongue's crevices and fissures that can trap odor-causing bacteria or food particles. This can be exacerbated by the consumption of aromatic foods (e.g., onions, garlic), certain beverages (e.g., alcohol, coffee), and tobacco smoking.

Pathologic halitosis can be caused by disorders of the oral cavity, such as gingivitis (i.e., gum inflammation) and periodontitis (i.e., gum disease). Defective dental restorations, unclean dentures, and oral abscesses may also be implicated in bad breath. Tonsillar pathology (e.g., tonsillitis, peritonsillar abscess), disorders of the respiratory tract (e.g., bronchiectasis, lung abscess), and structural gastrointestinal tract disorders (e.g., Zenker diverticulum, gastrocolic fistula) may cause pathologic halitosis.

Pseudo-halitosis is a psychological cause of halitosis and may be secondary to monosymptomatic hypochondriacal psychosis and olfactory reference syndrome, two psychiatric conditions where the individual erroneously believes they emit excess odor. Some individuals who have been treated for objective bad breath may develop psychological halitosis even after the bad breath is under control.

Excited Mo character in scrubs
Join millions of students and clinicians who learn by Osmosis!
Start Your Free Trial

What are the signs and symptoms of halitosis?

The signs and symptoms of physiologic halitosis are foul-smelling breath that is worse after waking up from sleep, and typically improves or resolves as the day progresses. Pathologic halitosis likewise presents with bad breath, typically not resolving over the course of a day and not associated with sleeping or waking. Depending on the pathologic cause, individuals may present with other symptoms, including erythema, swelling, and bleeding of the gingiva in the cases of gingivitis and periodontitis; enlarged, erythematous tonsils, in the case of tonsillitis; and fever, cough, shortness of breath and weight loss, in the cases of a lung abscess. Pseudo-halitosis can present as an individual reporting persistent bad breath affecting their daily life, however, on examination there is no objective evidence of halitosis. Individuals with halitosis, particularly pseudo-halitosis, may brush and floss their teeth multiple times daily and frequently rinse or gargle with mouthwash. Halitosis affects all ages, including children, although it is more commonly seen in the adult population with no discrimination on gender.

How is halitosis diagnosed?

The diagnosis of halitosis is often made by a healthcare provider (e.g., dentist, family clinician) based on a thorough medical history and physical examination. The provider may ask about oral hygiene practices, whether they breathe through their mouth, and about their dental history. During the physical examination, the healthcare provider may examine the teeth, gingiva, tongue, oral mucosa, and tonsils for abnormalities. At this time, they may perform organoleptic testing, where they assess the intensity of odor in the expired air, or the odor of a tongue scraping. The individual may be asked to refrain from oral hygiene (e.g., brushing teeth, using mouth rinse), using tobacco products, eating, drinking, or chewing gum for three hours prior to being examined.

How is halitosis treated?

Treatment of physiologic halitosis primarily focuses on oral hygiene, and it usually resolves immediately after brushing, flossing, eating, and drinking plenty of water. Brushing or scraping the tongue using gentle tongue scrapers and using antiseptic agents, such as toothpaste and mouthwash, before bedtime can help further reduce the bacterial load and reduce mouth odor. Behavioral modifications can help get rid of bad breath including maintaining good hydration, chewing sugar-free gum to stimulate salivary glands, decreasing alcohol, garlic, and onion intake, and stopping smoking. 

Treatment of pathologic halitosis includes addressing any underlying causes. For example, treatment involves debriding plaque in periodontitis; drainage and antimicrobial therapy for peritonsillar abscesses; replacing defective dental equipment; and endoscopic surgery to correct a Zenker diverticulum or gastrocolic fistula. Treating pseudo-halitosis involves reassurance. If significant concern persists despite reassurance, then referral to a mental health provider is indicated.

What are the most important facts to know about halitosis?

Halitosis, commonly known as bad breath, is a prevalent condition categorized into physiologic halitosis, often attributed to typical oral bacteria and low production of saliva; pathologic halitosis, linked to specific oral or systemic disorders; and pseudo-halitosis, a psychological perception without objective evidence. Physiologic halitosis is typically transient and improves with oral hygiene, while pathologic halitosis tends to present as persistent bad breath and associated symptoms. Diagnosis involves a thorough examination by dental professionals. Treatment focuses on oral hygiene for physiologic cases, addressing underlying health conditions such as gum disease for pathologic cases, and reassurance for pseudo-halitosis, with mental health referral if needed. Halitosis affects all ages, with a higher prevalence in adults. 

Watch related videos:

Mo with coat and stethoscope

Want to Join Osmosis?

Join millions of students and clinicians who learn by Osmosis!

Start Your Free Trial

Related links

Anatomy of the oral cavity
Gingivitis and periodontitis
Dental caries disease

Resources for research and reference

Aylıkcı BU, Colak H. Halitosis: from diagnosis to management. J Nat Sci Biol Med. 2013 Jan;4(1):14-23. doi: 10.4103/0976-9668.107255

Hughes FJ, McNab R. Oral malodour--a review. Arch Oral Biol. 2008 Apr;53 Suppl 1:S1-7. doi: 10.1016/S0003-9969(08)70002-5

Madhushankari GS, Yamunadevi A, Selvamani M, Mohan Kumar KP, Basandi PS. Halitosis - an overview: part-I - classification, etiology, and pathophysiology of halitosis. J Pharm Bioallied Sci. 2015 Aug;7(Suppl 2):S339-43. doi: 10.4103/0975-7406.163441. 

Scully C, Greenman J. Halitology (breath odour: aetiopathogenesis and management). Oral Dis. 2012;18(4):333-345. doi:10.1111/j.1601-0825.2011.01890.x

Torsten M, Gómez-Moreno G, Aguilar-Salvatierra A. Drug-related oral malodour (halitosis): a literature review. Eur Rev Med Pharmacol Sci. 2017;21(21):4930-4934.

Yaegaki K, Coil JM. Examination, classification, and treatment of halitosis; clinical perspectives. J Can Dent Assoc. 2000 May;66(5):257-61. PMID: 10833869.