At a recent coronavirus press conference, President Donald Trump claimed that using heat, light or injecting disinfectants such as bleach could be a possible cure to the coronavirus.

“I see the disinfectant that knocks it out in a minute, one minute,” Trump said during the briefing. “And is there a way we can do something like that by injection inside, or almost a cleaning? Because you see it gets inside the lungs and it does a tremendous number on the lungs, so it would be interesting to check that.”

These comments came after Bill Bryan, leader of the Department of Homeland Security’s Science and Technology Division, gave a presentation on current research his team is working on that referred to the virus not remaining viable as long when in warmer and humid temperatures. This may have gotten Trump thinking on ways to use this research for a cure, sparking his idea of injecting or shining UV light into the body. 

The President added, “So supposing we hit the body with a tremendous— whether it’s ultraviolet or just a very powerful light— and I think you said that hasn’t been checked because of the testing. And then I said, supposing you brought the light inside the body, which you can do either through the skin or some other way, and I think you said you’re going to test that, too.”

It is not known where the president’s idea for using disinfectants in the body comes from, but the possible source could be from letters he is receiving from Mark Grenon, the leader of a group claiming bleach is the “miracle cure” for COVID-19. The Guardian found Grenon’s letter said that chlorine dioxide (a powerful bleach that has potentially fatal effects when drunk) is a, “a wonderful detox that can kill 99% of the pathogens in the body.”

The US Food and Drug Organization has received a federal court order to stop the group, called Genesis II, from selling bleach as a cure or posting false information about its supposed ability to cure COVID-19 online.

The FDA also issued a warning to all Americans to not buy or drink the chemical from Genesis II, which is branded as “Miracle Mineral Solution” or MMS. They stated that it is a “dangerous bleach which has caused serious and potentially life-threatening side effects.”

Trump’s own claims on using disinfectant as a cure have been challenged by many medical professionals. Dr. Vin Gupta, a global health policy expert, said in an NBC News article that “This notion of injecting or ingesting any type of cleansing product into the body is irresponsible and it’s dangerous. It’s a common method that people utilize when they want to kill themselves.”

A spokesperson for Lysol told NBC News in a statement that warns against internal use of their product. 

Ryan Marino, a medical toxicologist and emergency physician at University Hospitals in Cleveland, also said in a Washington Post article, “I can understand looking at medicines that might have some effect or some sort of studies in a petri dish showing that they might work on a virus. But talking about putting ultraviolet radiation inside of the human body or putting antiseptic things that are toxic to life inside of living people, it doesn’t make any sense anymore.”

However, after a surge of backlash from medical professionals and others, the President seemed to backtrack on his comments by stating he was being sarcastic. He claimed the next day that he “was asking a question sarcastically to reporters like you just to see what would happen.” It is unclear whether or not this is the truth, as the president seemed completely serious when making the claims. He also claimed that he was not recommending Americans ingest or inject disinfectants when he posed the question. 

The use of ultraviolet light internally is unfounded in science. The use of UV light externally and on surfaces to kill viruses has been proved to be effective.  Researchers at the University of Columbia found for two other coronaviruses that using low level UV light could result in 99.9% viral inactivation in about 25 minutes. The light used in the study was UVC.

UVC is considered “hard” UV radiation and nearly all of it is absorbed high up in our atmosphere by the ozone layer.  Medical experts told PolitiFact, “applying UVC light directly to the body would damage genetic material and cause burns within seconds.”  Thus even applying UVC externally would be hazardous to humans.  It might prove useful to kill the bacteria in empty rooms and on non-living surfaces.

In a 2018 study published in Nature, researchers at Columbia University’s Center for Radiological Research found that far-UVC showed promise at killing microbes and neutralizing viruses without biological damage.  This was because far-UVC uses a narrow band of UVC that is unable to penetrate human skin or our cornea but still neutralize microbes and viruses.  A more recent study by some of the same researchers found that the same technique works on coronavirus and achieves “99.9% viral inactivation in [in about] 25 minutes.”

So while disinfectants and ultraviolet light are powerful tools to fight COVID-19, they are not designed or safe for use inside the human body.