Chlorhexidine
Chlorhexidine is a disinfectant and antiseptic that has been in medical
use since the 1950s. Oral rinse preparations are commonly used in
dentistry to reduce plaque build-up and treat gingivitis, and studies
show that it can reduce bacterial counts in saliva after as little as 30
seconds of exposure.34 There is more limited evidence
showing its virucidal effects. In vitro studies in the 1970s first
demonstrated activity of chlorhexidine gluconate against herpesvirus
strains though not poliovirus or adenovirus.35 Later
studies showed that chlorhexidine tends to have virucidal activity
against enveloped viruses, though does not show the same effect against
non-enveloped viruses. Bernstein et al showed virucidal activity of
chlorhexidine gluconate against the enveloped viruses herpesvirus 1,
cytomegalovirus, influenza A, parainfluenza, and hepatitis B after 5
minutes of exposure in vitro, with no activity against
poliovirus.36 Baqui demonstrated this effect against
human immunodeficiency virus 1 in vitro as well with two preparations of
chlorhexidine as well as Listerine mouthwashes.37There are few studies examining chlorhexidine and coronaviruses, and
those that do exist examine the effects of chlorhexidine on
sterilization of inert surfaces rather than living tissue. These studies
do, however, show sensitivity of coronavirus to chlorhexidine though
only when used in combination with other compounds such as ethanol or
cetrimide.38 In isolation, chlorhexidine has been
found to be less effective against coronaviruses than PVP-I in both
in-vitro studies and studies of disinfection of inanimate
surfaces.15,39 Overall, there are limited data
demonstrating the activity of chlorhexidine against coronaviruses and it
is also associated with high levels of ototoxicity and can be flammable
when utilized in commercial preparations that commonly include
alcohol.31,33