Is nose hair important to ward off colds and other viral diseases? I ask that as a woman who raised her eyebrows before the pandemic. The person doing the wax would always recommend waxing my nose hairs.

A medical truism says that nasal hairs filter the air we breathe and thus protect us from infection by airborne viruses, bacteria and other pathogens. But as is so often the case with truisms, his story is more venerable than confirmed.

The idea that our nasal hairs, medically called vibrissae, could offer protection against infectious germs goes back more than a century. In 1896, two English doctors stated in the prestigious medical journal The Lancet:

The interior of most normal nasal cavities is completely aseptic [sterile]. On the other side are the vestibules of the nostrils [nostrils], the vibrissae that line them and any crusts that form there are generally populated by bacteria. These two facts seem to demonstrate that the vibrissae act as a filter and that large numbers of microbes find their fate in the damp webs of hair that surround the vestibule.

The conclusion of the English doctors may sound logical, but at the time no one had investigated whether trimming nasal hair could make it easier for germs to enter the airways.

It was not until 2011 that the density of nasal hairs was intensively investigated as a possible disease correlate. In a study of 233 patients published in the International Archives of Allergy and Immunology, a team of researchers from Turkey found that people with thicker nasal hair are less likely to have asthma. The researchers attributed this finding to the filter function of the nasal hair.

Your observation was interesting, but it was an observational study that cannot prove cause and effect, and asthma is not an infection. The researchers also didn’t conduct any follow-up studies to assess how trimming the hairs of the nose might affect the risk of asthma or infection.

It was not until 2015 that doctors at the Mayo Clinic conducted the first and, to date, only study examining the effects of trimming nasal hair. The researchers measured nasal airflow in 30 patients before and after trimming their nasal hairs and found that trimming resulted in improvements in both subjective and objective measurements of nasal airflow. The improvements were greatest in those who initially had the most nasal hairs. The results were published in the American Journal of Rhinology and Allergy.

An interesting conclusion here, too, but does better nasal breathing correlate with a higher risk of infection?

None of the studies addressed this question directly. But dr. David Stoddard, lead author of the Mayo study, noted that when someone is working with drywall, for example, “I can tell by the white dust in the hair on their nose that they have just come home. But it’s the larger particles that get stuck in the hairs of the nose. Viruses are much smaller. They’re so small that they’ll likely go through your nose one way or another. I don’t think trimming the hair on the nose would increase the risk of a respiratory infection. “

Based on the limited study of nose hair, there is no evidence that trimming or waxing increases the risk of respiratory infections. And as at least one expert who has worked in the field has speculated, this is likely not the case.