Fact check: Leaving raw onions around your house won’t prevent illnesses

Katie Landeck

The claim: Onions left out around the house will absorb germs and will keep people in the home healthy.

An old wives' tale that keeping raw, unpeeled onions out will keep your family safe from illnesses such as the flu is making the rounds on Facebook. 

The post has been circulating for years, regularly resurfacing during bad flu seasons or during the H1N1 outbreak in 2009. A copy-and-paste shared by Teri Bloom, who said her grandmother effectively treated her colds and fevers with onions, gained traction.

The post says that during the flu pandemic in 1919, an unnamed doctor discovered a healthy family that had set out unpeeled onions that “absorbed the bacteria,” keeping the family healthy. The post claims that more recently, an unnamed hairdresser used unpeeled onions successfully in her shop. The post talks about a friend using onion to treat pneumonia. 

“I came across an article that said to cut both ends off an onion, put it into an empty jar, and place the jar next to the sick patient at night,” the post says. “It said the onion would be black in the morning from the germs ... sure enough, it happened just like that ... the onion was a mess and I began to feel better.”

The post does not specifically talk about COVID-19. 

The post claims onions can cause food poisoning as they are a “magnet” for bacteria. 

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Onions as a folk remedy

Leaving unpeeled onions out has been cited as a folk remedy since at least the 1500s, according to a Snopes fact check in 2009 on a similar post. It’s so common a legend that it’s even slipped into an episode of "The Simpsons." 

Fact checks by Snopes, The Wall Street Journal and The Associated Press found no scientific evidence that onions filter the air.

"There is no scientific evidence that a cut raw onion absorbs germs or rids the air of toxins/poisons,” the National Onion Association says on its website. 

"In fact, the onion’s own juices are antimicrobial, which means they will fight bacteria rather than attract it," the trade group says.

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It points out cold and flu viruses are primarily spread by contact, “not by floating in the air where the onion can supposedly attract or destroy them.”

Health benefits of onions

Onions do have some medicinal and pharmacology uses recognized by the World Health Organization. Onion tea is listed in WHO literature as a way to help with a runny nose, as an example.

The WHO points to four scientific articles over the years in which onions were found to kill pathogens related to food poisoning, a claim that the National Onion Association makes as well. 

"The Center for Food Safety at the University of Georgia states that juice released from cut onion is known to kill or inhibit the growth of several types of microorganisms, including some of those capable of causing food poisoning in humans," the trade group says.

Our rating: False

We rate the claim that raw onions can help prevent illness or keep people healthy as FALSE, based on our research. Though onions have recognized health benefits, there is no scientific evidence that an unpeeled onion can absorb germs and protect from viruses or bacteria. It’s also false that onions are a magnet for food poisoning.

Our fact-check sources:

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Our fact check work is supported in part by a grant from Facebook.