There is no known cure for the new coronavirus.
It’s a tough battle. On social media, memes have become efficient vectors of bad advice, often with urgent instructions or dystopian graphics. One, misstating the benefits of gargling salty water, shows the virus as a cluster of green burrs infecting the throat of a glowing blue man.
One series of posts with bad advice — including claims that sunshine could kill the virus and that ice cream should be avoided — tacked on the name UNICEF.
“This is, of course, not true,” said Christopher Tidey, a spokesman for UNICEF, the United Nations Children’s Fund.
“Misinformation during times of a health crisis can result in people being left unprotected or more vulnerable to the virus,” he said. “It can also spread paranoia, fear and stigmatization, and have other consequences, like offering a false sense of protection.”
Here are some of the false claims that are spreading via Twitter, Facebook and WhatsApp.
Gargling warm water
There is no evidence that gargling warm water with salt or vinegar “eliminates” the coronavirus, a claim that has gone viral as part of a meme — the one with the glowing blue man — in multiple languages. It suggests that the coronavirus lingers in the throat for days before it reaches the lungs, and that a good gargle can stop the virus in its tracks.
That’s not true. The Centers for Disease Control and Prevention has said that gargling salty, warm water is one of many ways to soothe a sore throat, but there is no evidence that doing this will kill the coronavirus.
“It won’t stop it from getting into the lungs,” said Dr. Paul Offit, an infectious disease expert at the University of Pennsylvania and the Children’s Hospital of Philadelphia. “What it could do is decrease inflammation, which would make your throat less sore.”
Drinking water frequently
Some social media posts suggest that if you sip water every 15 minutes or so, you can protect yourself from the virus — which, in this scenario, has made its way to your mouth — by flushing it into your stomach. The idea here is that it wouldn’t enter your trachea, which leads to the lungs.
But that’s false. Staying hydrated is a good idea generally, and the C.D.C. says that healthy people can get their fluid needs by drinking when thirsty and with meals. But there is no evidence that frequent sips keep the virus from entering the lungs.
Blasting hot air
A video that has been shared on Facebook claims that the virus cannot survive in hot temperatures. It shows a woman aiming a hair dryer at her face with the goal of heating her sinuses to the “coronavirus kill temperature” of 133 degrees. Elsewhere on social media, people have suggested that hand dryers can kill the virus.
But there is no clear evidence that this works. According to the World Health Organization, the virus cannot be killed by hand dryers, and it appears that it can survive in hot temperatures (and in cold temperatures).
Dr. Offit said that there was some research indicating that warming the nasal passage might help the immune system combat a virus. But he added that breathing near steam — like sitting over a bowl of hot soup — was a much better idea than aiming a hair dryer at your face.
“Do the soup thing,” he said. “That’s better than forcing air into your nose.”
Ingesting colloidal silver
Many claims about the benefits of colloidal silver come from companies that sell the product.
Colloidal silver comes in different forms — often as a bottled liquid with silver particles — and is promoted as a dietary supplement. But according to the National Center for Complementary and Integrative Health, evidence about the medical benefits are lacking, and silver can be harmful. One possible side effect is a condition called argyria, a blue-gray skin discoloration. Colloidal silver could also hinder the absorption of some drugs.
Last week, the Food and Drug Administration said that it had warned seven companies to stop selling products, including colloidal silver, that the companies suggested cure or prevent the coronavirus.
Taking your vitamins
Social media is full of suggestions about taking additional vitamins — C is a popular one — and ingesting things like garlic, pepper, mint or elderberry. But there is little evidence that these foods and supplements can protect you in any consistent or significant way.
Vitamin C, which is an antioxidant, hasn’t shown a consistent benefit for treating or preventing illnesses like the common cold. And as with many things, it can be harmful in large doses. “Do not take large quantities of an antioxidant knowing that your body needs to maintain a balance,” Dr. Offit said.
Evidence that elderberry can help people with flu symptoms is spotty. Garlic may have some antimicrobial properties, but there is no evidence that it has protected people from the coronavirus.
In short, vitamins and nutrients can be good, especially if they come from a balanced diet. But they can’t be relied upon to protect people from a pandemic.
So what should we do?
“Sound preparation, based on scientific evidence, is what is needed at this time,” said Mr. Tidey, of UNICEF.