In 1895, a physician by the name of F.A. Colby published a correspondence in the Boston Medical and Surgical Journal; his letter was titled, "Should Doctors Wear Beards?"

"I wear a beard," Dr. Colby wrote, "and grant you that probably, like many of my professional brothers, it is a comfort to stroke it and look wise while making a doubtful diagnosis. It is a comfort in the cold, bleak days of winter...I cultivated mine sedulously after graduation, so that I might lose the title of 'the young doctor.'"

His words still ring true in 2017. As a first-year doctor, I’ll sometimes go stretches without shaving on busy clinical rotations. I’ve noticed patients and staff treat me with more seniority when I’m bearded compared to clean-shaven. My patients no longer ask when I graduated from medical school. Supervising doctors no longer mistake me for a medical student. A bit of facial hair seems to add years of perceived expertise.

For male physicians, it might then be appealing to grow a beard. We can hide our insecurities and pretend to be wiser than our years, all while crossing off another daily chore.

Still, Dr. Colby's 1895 letter brings up a longstanding controversy over whether physicians should be growing beards at all—hygiene.

"We note with what care the surgeon disinfects his hands, arms, instruments, all that comes in contact with the patient in a surgical case," Dr. Colby wrote,"but the beard of the doctor attending diseases and so easily communicable as some are, how many thoroughly disinfect that before visiting the next patient? Surely we should take every precaution, or not wear beards."

Colby's concerns found their way into the next century, as researchers began to study the question of beard hygiene. In 1967, a study titled, "Microbiological Laboratory Hazard of Bearded Men" appeared in the journal Applied Microbiology. The authors tested "the hypothesis that a bearded man subjects his family and friends to risk of infection if his beard is contaminated by infectious microorganisms while he is working in a microbiological laboratory."

After culturing bacteria and spraying volunteers' beards, the researchers sampled the beards at different time intervals and following various forms of washing. The study found “beards retained microorganisms and toxin despite washing with soap and water.” The authors also showed that infectious diseases could be transmitted from a beard to animals like chickens and guinea pigs.

With respect to beards in clinical situations, the study had several shortcomings. Its sample size was small, with just four bearded volunteers and a bearded mannequin—yes, a bearded mannequin. The researchers introduced bacteria and toxins to the beards, rather than studying beards in their natural states. The focus was on microbiology laboratories and did not include broader hospital settings.

Nonetheless, later studies raised similar concerns about the possible infectious risks of beards. For example, a 2000 study in the journal Anaesthesia examined the effectiveness of surgical masks for preventing bacterial contamination, finding bearded subjects shed considerably more bacteria—even when wearing masks—compared to non-bearded subjects. The authors recommended that surgical personnel “avoid wiggling the face mask” and that “bearded males may also consider removing their beards.”

The presumption had long held that beards were unclean and bacteriogenic. Now, there was growing evidence to support that claim for laboratories and hospitals.

But in the last few years, new studies have cast doubt on the dangers of beards in the healthcare settings. In 2014, one of the largest studies on this topic upended the prevailing wisdom. The study examined over 400 medical staff and found bacterial colonization was “similar in male healthcare workers with and without facial hair." Of note, staff without facial hair had higher rates of colonization with pathogenic bacteria like methicillin-resistant coagulase-negative staphylococci.

Published in 2016, another study–titled “To Beard or Not to Beard? Bacterial Shedding Among Surgeons”—re-examined the question of beard hygiene in surgical settings. The authors compared bearded and clean-shaven subjects who performed facial motions behind surgical masks. This time, however, "bearded surgeons did not appear to have an increased likelihood of bacterial shedding compared with their nonbearded counterparts while wearing surgical masks."

The cleanliness of health care providers’ facial hair might seem like a mundane question to pore over. But, in medicine, the mundane aspects of hygiene can have profound effects on patient care.

Surveys suggest between 700,000 and 1.7 million healthcare-associated infections (HAIs) occur in US hospitals every year. Researchers estimate HAIs incur up to $147 billion in direct and indirect annual costs. To curb these trends, hospitals emphasize the use of hand sanitizers, disinfectant wipes, sinks, gowns, and an array of infectious disease protocols. Some hospitals have even installed motion sensors and video cameras to promote hand washing among their staff.

Debates over hair hygiene are inciting controversy among leading medical organizations. For instance, the Association of periOperative Registered Nurses, an organization representing over 40,000 nurses, issued guidelines calling for stricter hair covering in operating rooms. These regulations, which led some hospitals to change surgical attire, have stirred outrage among surgeons. The American College of Surgeons released competing guidelines last year, directly challenging the nursing group's proposals.

And it’s not just hair. Nearly every aspect of a doctor's attire has come under fire for cleanliness in recent years. White coats, stethoscopes, and ties have all been called out for hygiene concerns.

Healthcare-associated infections remain a pressing issue, but the jury is still out on whether beards truly pose a risk to patients and colleagues in clinical care. After 122 years, we’ve yet to answer Dr. Colby’s question:

"In these days of microbes, bacilli, and crawling, creeping and flying things that find a resting-place for development of diseases in the human system, coming from the air we breathe, liable to assault the weak and strong...should doctors wear beards?"