The U.S. Food and Drug Administration has issued a sternly worded letter to the company that makes Purell hand sanitizer: stop claiming your product can help prevent viral diseases like influenza, Ebola and others.

In the letter, sent to Gojo Industries earlier this month, the health regulator takes issue with the fact that the marketing around the company's hand sanitizer makes it seem to be a pharmaceutical drug, not an over-the-counter antiseptic. If it were a drug, the product would be subject to a slew of rigorous testing protocols that must prove it actually does what it claims it will.

Across various websites and social media channels, the FDA says, the company repeatedly makes the claim that the product "kills more than 99.99 per cent of most common germs that may cause illness" including specific viruses such as Ebola, MRSA, VRE, norovirus, influenza, and Candida auris.

Purell is essentially 70 per cent ethyl alcohol, mixed with small amounts of other chemicals. While numerous scientific studies have shown that alcohol does indeed kill or otherwise inactivate a number of viruses, the FDA says that doesn't mean Purell can make unsubstantiated claims about their product, including that it can help prevent people from getting sick from specific viruses.

"FDA is currently not aware of any adequate and well-controlled studies demonstrating that killing or decreasing the number of bacteria or viruses on the skin by a certain magnitude produces a corresponding clinical reduction in infection or disease caused by such bacteria or virus."

The FDA also took issue with the company's claim that its product can help lower absenteeism in schools, with one claim that unnamed studies have shown the product can cut the number of sick days by students and teachers by more than half.

The letter's main complaint is that by making those claims, the manufacturers are making the product seem like a drug — which means it is subject to much more scrutiny. Over-the-counter antiseptics such as rubbing alcohol do not, in fact, face this scrutiny.

"As currently formulated and labeled, Purell Healthcare Advanced Hand Sanitizers are unapproved new drugs in violation of section 505(a) of the Federal Food, Drug, and Cosmetic Act," the FDA said.

"You should take prompt action to correct the violations cited in this letter," the FDA said. "Failure to promptly correct these violations may result in legal action without further notice, including, without limitation, seizure and injunction."

The company appears to have already taken steps to address the matter, as a FAQ on Purell's website has already been cleansed of the passages with which the FDA took issue.

"Purell Hand Sanitizer products are tested against a broad spectrum of micro-organisms and have resulted in more than 99.99 per cent reduction of those organisms," a section of the website now reads. "It is prohibited by the Food and Drug Administration for manufacturers to make viral reduction claims."