Halitosis, commonly known as bad breath, is an unpleasant odor emanating from the mouth, often resulting from the breakdown of food particles and debris by bacteria. Clinical observations during the pandemic have indicated a noticeable increase in halitosis among individuals infected with the SARS-CoV-2 virus. Understanding the mechanisms behind this phenomenon requires examining how the viral infection affects the body’s oral and systemic environments.
The Direct Link to COVID-19
Halitosis is not classified among the primary symptoms of COVID-19, such as fever or cough. However, it is a frequently reported secondary complaint; some studies noted that approximately 10.5% of patients with mild to moderate symptoms experienced halitosis, often alongside dry mouth (xerostomia). SARS-CoV-2 gains entry to cells by binding to the angiotensin-converting enzyme 2 (ACE2) receptors, which are abundant on the tongue’s surface. This binding can cause epithelial changes on the tongue, creating an environment conducive to the proliferation of odor-causing bacteria.
Oral Environment Changes Caused by the Virus
The local environment inside the mouth is altered by the infection. Xerostomia, or dry mouth, is a prevalent oral symptom in COVID-19 patients, reported in over 40% of cases. This occurs because the virus can attack ACE2 receptors in the salivary glands, reducing saliva production. Since saliva is a natural cleanser that controls bacterial populations, its decrease allows odor-producing bacteria to flourish unchecked.
The loss of smell and taste (anosmia and dysgeusia) also contributes indirectly. When these senses are impaired, individuals may not perceive their own breath odor or may be less motivated to maintain rigorous oral hygiene. Furthermore, the compromised immune status can lead to opportunistic infections, most notably oral candidiasis (oral thrush). This fungal infection is characterized by white patches and can produce foul odors. The use of certain medications, such as antibiotics or steroids, during treatment can also disrupt the oral microbiome.
Systemic Factors Contributing to Breath Odor
Several systemic factors related to the overall illness can lead to noticeable breath odor. Reduced food intake and dehydration are common during illness, initiating a metabolic state known as ketosis. When the body burns fat for energy, it produces ketones. One ketone, acetone, is released through the breath, resulting in a distinct sweet, fruity, or pungent odor often described as similar to nail polish remover.
Respiratory symptoms, such as sinusitis and nasal inflammation, also contribute to extra-oral halitosis. Inflammation leads to excessive mucus production, causing post-nasal drip. This drainage accumulates on the back of the throat, where bacteria break it down, releasing volatile sulfur compounds (VSCs) that contribute significantly to bad breath. Measurement of VSCs in the breath of COVID-19 patients has shown elevated levels.
Strategies for Managing Halitosis During Recovery
Addressing halitosis requires targeting the underlying oral and systemic causes. Maintaining optimal hydration is primary, as drinking water stimulates saliva flow to combat xerostomia and helps flush out odor-causing ketones. Chewing sugar-free gum or sucking on mints containing xylitol can also increase salivary production. Meticulous oral hygiene must be practiced, including consistent flossing and using a tongue scraper to remove bacterial biofilm. If the breath odor is accompanied by white patches or discomfort, consult a healthcare provider to check for and treat secondary infections like oral candidiasis.