Gentle cleansers as effective at killing viruses as harsh soaps

Gentle cleansers are just as effective in killing viruses — including coronavirus — as harsh soaps, according to a new study conducted by the University of Sheffield and published in the journal Frontiers Virology.

Healthcare professionals often substitute harsh soaps or alcohol-based hand sanitisers with skin-friendly cleansers in order to treat or prevent irritant contact dermatitis — a common skin disease which causes red and swollen skin with a dry and damaged surface. As noted by lead author Dr Munitta Muthana, “Not only does irritant contact dermatitis cause the skin to become inflamed, blister and crack, which increases transmission of bacteria and viruses, it can also lead to less compliance with personal protective equipment (PPE) and inadequate handwashing for fear of making symptoms worse.”

Despite the widespread use of gentle cleansing products for handwashing, there has been limited evidence to show the efficacy of the products to prevent the spread of viruses such as human coronavirus, herpes simplex virus, norovirus and influenza. Scientists from the Sheffield Dermatology Research (SDR) group have now addressed this by testing multiple handwash products, including antibacterial soap, natural soap, foam cleansers and bath wash products.

The team investigated the products’ ability to kill enveloped viruses such as human coronavirus and influenza, which have an additional layer of structural protection, as well as non-enveloped viruses such as norovirus and adenovirus. Their findings show gentle cleansers were effective in killing enveloped viruses, but non-enveloped viruses displayed resistance against skin-friendly cleansers as well as harsh soaps.

“For the first time, our study has shown substituting harsh soaps with milder wash products such as gentle cleansers is effective in fighting against enveloped viruses, including human coronavirus, which is very encouraging — especially for those in jobs in which irritant contact dermatitis is an occupational hazard,” Muthana said. “We also found that using additional agents such as moisturisers to help protect the skin didn’t prevent the products’ antiviral activity, which means we don’t have to use very harsh products on our skin in order to kill viruses.”

The study found non-enveloped viruses demonstrated greater resistance across all types of handwashing products tested, including harsh chemical substances and milder solutions. Norovirus — known as the winter vomiting bug — was the most resilient.

“Even when we increased the exposure of norovirus to the handwashing products from 20 seconds to one minute, the virus wasn’t disrupted,” said PhD researcher Natalie Winder, first author of the study. “Bleach was the only agent which affected the virus; however, bleach-based handwashes are not a feasible option due to its corrosivity, which would be extremely harmful to the skin.

“Measures such as isolation and disinfecting surfaces with bleach are more effective in preventing the spread of the norovirus infection and more research needs to be done to see whether heavily diluted bleach-based handwashes, which are safe to use on the skin, can be produced.”

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