Unsupported: Wearing face masks is not associated with any dental problem, such as so-called “mask mouth”, a term not used in scientific publications or by the healthcare community.
FULL CLAIM: Masks are dirty and cause bacterial overgrowth, skin infections, and “mask mouth, [which is] a new medical condition caused by wearing masks all day”
Facebook posts claiming that face masks promote bacterial and fungal overgrowth and lead to skin and oral infections (see examples here, here, and here) went viral in late September 2020. As we explain below, these claims are unsupported as scientific evidence shows that, for the general population, there are no oral or skin infections associated with wearing face masks. Previous claims linking the use of face masks with weakened immune systems, reduced oxygen levels, or lung infections, are incorrect, as Health Feedback explained here and here.
Infected individuals transmit the virus that causes COVID-19 mainly through respiratory droplets generated by coughing, sneezing, and talking. According to estimates from the U.S. Centers for Disease Control and Prevention, approximately half of COVID-19 transmission occurs before symptoms appear in infected individuals, facilitating the spread of the virus[1-3]. Face masks act as a physical barrier that reduce the spread of the virus from infected individuals before they are aware that they are infected.
Although wearing face masks for prolonged time periods can cause discomfort or skin irritation, there is no evidence that they cause bacterial overgrowth or infections, according to Misha Rosenbach, an associate professor of dermatology at the Hospital of the University of Pennsylvania:
“Cloth masks have been used in the operating room since the 19th century, and modern surgical masks since the 1960s. Some surgical procedures take hours, sometimes 10, 12, or even 18 hours. Surgeons wear masks continuously throughout this period. There is no evidence that doing so increases risk of bacterial or fungal infection. The entire field of dermatology has not seen an uptick in facial infections, skin infections, lip/nose/tongue infections, and our colleagues in oral medicine and dentistry have not observed or reported on any increase in rates of infection during the pandemic period.”
In addition, Howard Maibach, professor of dermatology at the University of California, has not observed any skin infections associated with wearing face masks: “So far, we have not seen any significant [increase in] microbiological infection of the common skin infections. The closest would be […] a slight increase in their acne, a slight increase in something called rosacea”, which is a skin condition that results in facial redness and swelling. However, Maibach points out that in order to establish a causal association between these slight increases and the use of face masks, scientists need to conduct a study including a non-mask wearing control group.
Some posts make the unsupported claim that wearing masks causes “mask mouth”, an alleged dental problem involving cavities, gum disease, and bad breath. However, experts warn that there is no scientific basis for that claim, and that dentists wear face masks for long periods of time without any impact in their oral health. Ramesh Gowda, president of the Orange County Dental Society, explained to Los Angeles Times that “if people are having increased dental issues, it’s likely due to poor oral hygiene.”
Therefore, dermatology and oral health experts encourage individuals to wear face masks and follow the proper sanitation guidelines to reduce the spread of COVID-19. Rosenbach explains, “masks are an incredibly effective public health tool, and essential in stemming the spread of SARS-CoV-2, the virus that causes COVID-19. While initially there was a lack of scientific certainty about the level of protection that different masks conferred, it is now clear that masks are helpful.”
Although effective, wearing face masks does not confer complete protection from infection with the virus that causes COVID-19. Therefore, face masks should be used in combination with regular hand washing and physical distancing to further reduce COVID-19 transmission. In order for masks to be effective, they should cover the area around the mouth and nose without being too tight. The American Academy of Dermatology provided some tips that people can take to prevent excessive dryness and skin irritation from wearing face masks, including correct hydration and washing or discarding masks after each use.
Finally, Rosenbach notes that the individual responsibility of wearing a face mask to reduce COVID-19 transmission should go hand in hand with the production of more effective and comfortable masks. “I’m a doctor, and every doctor I know, along with every nurse, respiratory therapist, janitor, front desk staff, security guard, and everyone else in the hospital wishes, if anything, for more masks – for the population as a whole to mask up, but also for more production of better fitting, better filtering, and easier-to-wear masks that we can all comfortably use long-term,” he said.
In summary, the claim that wearing face masks causes bacterial overgrowth, skin infections, or impairs oral health is unsupported. Wearing face masks reduces the spread of respiratory droplets that facilitate the spread of COVID-19 without posing any health risk to the general population.
Misha Rosenbach, Associate Professor, Hospital of the University of Pennsylvania:
There is no evidence that wearing masks leads to bacterial overgrowth or causes infections. Physicians, nurses, and other frontline healthcare workers have been wearing masks in a variety of settings for decades to centuries at this point. Cloth masks have been used in the operating room since the 19th century, and modern surgical masks since the 1960s. Some surgical procedures take hours, sometimes 10, 12, or even 18 hours. Surgeons wear masks continuously throughout this period. There is no evidence that doing so increases the risk of bacterial or fungal infection. The entire field of dermatology has not seen an uptick in facial infections, skin infections, lip/nose/tongue infections, and our colleagues in oral medicine and dentistry have not observed or reported on any increase in rates of infection during the pandemic period.
Occasionally, as you’re wearing a mask, you may be aware of your breath—and sometimes your breath may smell bad. Most people are aware of “morning breath.” You can wake up from a night’s sleep (obviously with no mask), and have bad breath—this can be due to small food particles, insufficient brushing or flossing, and some bacterial growth. Occasionally, eating certain foods, or being dehydrated, can lead to odors in the breath. Specific diets, such as the ketogenic diet, can generate an odor of ketosis. Reflux or ulcers can occasionally be associated with an odor as well. However, none of these are caused by mask wearing. People had bad breath before we were all wearing masks; they’ll have bad breath after that too. If the smell is bothersome, you can consider chewing gum or using a lozenge or sucking candy. But the odor under a mask is a small price to pay for the protection it offers.
Masks are an incredibly effective public health tool, and essential in stemming the spread of SARS-CoV-2, the virus that causes COVID-19. While initially there was a lack of scientific certainty about the level of protection that different masks conferred, it is now clear that masks are helpful. And not just “my mask protects you, your mask protects me” (if I wear a mask, and am infected, I breath out and spread less virus), but beyond that, wearing a mask means that if you come into contact with the virus, you are likely to be exposed to a lower amount of virus, and give your body and immune system a chance to respond better, with better outcomes. It is important to pay attention to where your information is coming from, and what it’s based on. The recommendation to wear masks is from doctors, infectious disease experts, epidemiologists, and those leading the efforts to curb the pandemic. Countries with widespread mask use have lower rates of infection, fewer infected patients, and better outcomes – and are able to get back closer to ‘normal’ life, with their economy doing better, and more places of business and schools able to open, and able to stay open.
I’m a doctor, and every doctor I know, along with every nurse, respiratory therapist, janitor, front desk staff, security guard, and everyone else in the hospital wishes, if anything, for more masks—for the population as a whole to mask up, but also for more production of better-fitting, better-filtering, and easier-to-wear masks that we can all comfortably use in the long term.
Howard Maibach, Professor, School of Medicine, University of California, San Francisco:
At my institution, I am available seven days a week, 24 hours a day. If any employee in our three large hospitals thinks they’re having a mask-related problem, they can be seen. So far, we have not seen any significant microbiological infection, like common skin infections. The closest would be a very complicated causation. Namely, some people seem to have had a slight increase in their acne and a slight increase in something called rosacea. But no, really, that is not a quantitative observation since we don’t have a control group.
- 1 – Kimball et al. (2020) Asymptomatic and Presymptomatic SARS-CoV-2 Infections in Residents of a Long-Term Care Skilled Nursing Facility — King County, Washington, March 2020. Morbidity and Mortality Weekly Report.
- 2 – Wei et al. (2020) Presymptomatic Transmission of SARS-CoV-2 — Singapore, January 23–March 16, 2020. Morbidity and Mortality Weekly Report.
- 3 – Li et al. (2020) Substantial undocumented infection facilitates the rapid dissemination of novel coronavirus (SARS-CoV-2). Science.
- 4 – Allsopp et al. (1997) Survey of the use of personal protective equipment and prevalence of work related symptoms among dental staff. Occupational and Environmental Medicine.