Soap substitute kills Covid just as well as alcohol sanitiser, study shows

It’s good news for chapped hands: an antimicrobial soap substitute commonly used by people with dry and itchy skin conditions has been shown to kill coronavirus.

Since the start of the pandemic, people with no history of eczema or dermatitis have been developing sore and cracked skin as a result of increased hand-washing or using alcohol sanitiser gel.

Usually, people with such “irritant contact dermatitis” would be advised to use a soap substitute such as Dermol 500. It contains an emollient to help keep skin hydrated, plus the antimicrobial agents benzalkonium chloride and chlorhexidine dihydrochloride to prevent raw skin from becoming infected with bacteria or fungi.

The British Association of Dermatologists (BAD) had advised against this, as there was no evidence that these substances could deactivate coronavirus. But now Rachel Edgar, a virologist at Imperial College London, and her colleagues have shown that Dermol 500 not only destroys the Sars-CoV-2 virus that causes Covid-19, it can also deactivate flu viruses.

They incubated these viruses with either diluted Dermol solution or various alcohol-based hand sanitisers and then assessed their ability to infect human cells.

“We found that Dermol 500 performed as well or better than these alcohol-based sanitisers at decreasing viral infectivity, and that the longer the incubation time, the greater the reduction in infectious virus,” said Edgar, whose results have not yet been peer-reviewed. When used as directed in the instructions, Dermol should deactivate the virus within 30 seconds, she added.

Further experiments revealed that both benzalkonium chloride and chlorhexidine dihydrochloride could deactivate the viruses. Although these antimicrobials aren’t found in other soap substitutes within the UK, benzalkonium chloride is used as a preservative in many nasal sprays, including some decongestant sprays and those used to treat hay fever. They are also found in some disinfectants.

“For those people who are suffering, if they can safely use these emollients instead of alcohol gels or hand washing with soap, then that will certainly improve any skin irritation that they have, and may increase compliance with the infection control measures,” Edgar said. “In turn, this will decrease instances of staff sickness, or restriction from clinical work due to skin disease.”

Dr Tanya Bleiker, the president of the BAD, said: “It is pleasing to see that research is being done on whether soap substitutes such as Dermol can be safely used to prevent the spread of the virus. That said, more research is necessary before we can have sufficient confidence to overturn the current recommendations, and to be sure that Dermol is effective against Sars-CoV-2 in real-world conditions rather than just in the lab. We know that how you wash your hands is as important as what you wash them with.”

However, she said a soap substitute could be used at home when there is no infection risk.