Can Onion Water Cure Colds or Flu?

Onion water is a pretty big thing lately.  

Making onion water is easy. Chop up a raw red or yellow onion, pop it into a jar or other vessel. Fill the onion vessel with filtered water, let it soak overnight in the refrigerator and congratulate yourself: you’ve just made one of the trendiest, terrible tasting, most magical home remedies on social media. But is it really?

In addition to its purported cold and flu curing powers, onion water has also long been a staple among the bodybuilding crowd – legend has it that onion water can increase testosterone. A much-touted study suggests that rodents who consumed a LOT of onion water increased their testosterone by 300 percent; however no verification that this effect can be replicated in humans seems to exist.  

Onion juice, more concentrated than onion water, has been embraced by a subset of people with thinning hair or hair loss as a regenerative treatment, with helping them restore their locks to their former thick, shiny glory. You don’t ingest the onion juice for this remedy, you rub it into your scalp.

Putting sliced onions in your socks, so that the slices are pressing against the soles of your feet, is another onion-flavored folk remedy. For this one, you sleep with your onion socks on and wake up cured of your cold or flu.  

Yet more onion remedies include boiling a white onion in milk then consuming the milk and the onion to cure a cold; microwaving half an onion until it’s nice and warm (not scalding) and pressing it to your ear to cure ear infections or earaches; rubbing half a raw onion on a wasp sting to relieve the pain and making a poultice of fried onions on a piece of flannel to relieve a cough.

A traditional folk remedy listing on a website also claimed that onions, either ingested or placed on various body parts, could also mitigate or cure erectile dysfunction, fainting, dysentery, warts, hiccups, moles, heat stroke, cysts, burns, gonorrhea and heart disease.

Like onions, these claims are best taken with a grain (make that a generous sprinkle) of salt. There is no scientific basis for any of these claims. While we don’t recommend you substitute onions for a visit to your doctor when you’re under the weather, we do acknowledge that onions contain beneficial nutrients and antioxidants and are a healthy part of a vegetable-rich diet. 

Why might drinking onion water make you feel better when you have a cold or the flu?

Hydration. The provable benefit to drinking onion water to feel better when you’ve got a cold is right there in the name. Onion water. Anything you can do to up your fluid intake when you’re sick will help you feel better. Staying hydrated when sick will help keep mucus thinned down and moving and your mucus membranes moist. Doing so helps you feel less congested.  

Antioxidants. One of the powerful antioxidants found in onions is quercetin, which according to Keri Gans, a dietician and author of the book The Small Change Diet, has shown that it “may help our body reduce inflammation, inhibit growth of bacteria and support immune health.” Eating an onion would be a better idea, because you’d also benefit from the fiber contained in an onion. 

Placebo effect. This is when your brain convinces your body that a fake (or ineffective/unproven) treatment is real and, because of that belief, stimulates your body to heal. The placebo effect can’t, say, shrink a tumor or lower your cholesterol level but it can affect symptoms controlled by your brain. For example, the placebo effect could help you feel less pain, fatigue or nausea.  

Why might drinking onion water make you feel worse when you have a cold or the flu?

Heartburn. Onions are a very acidic food. If you suffer from acid reflux, you already know to limit your onion intake. Onions don’t cause heartburn in all people, and they’re more likely to give you trouble when raw than cooked. 

Allergies. Onions can cause nasal congestion, red eyes, itchy nose and eyes, nasal congestion and asthma thanks to compounds they contain called diallyl disulfide and lipid transfer protein.

Painful gas. People who have irritable bowel syndrome (IBS) or sensitive digestive systems (you know who you are), onions can be tough to digest because of their soluble fiber. They are able to pass through the small intestine largely undigested and when they get to the large intestine, they quickly begin to ferment. For most of is, that means a little gas. For folks with IBS, it means abdominal pain, severe cramping and bloating, gas and painful or uncomfortable bowel movements.

Onion scented breath and sweat. Technically, smelling like an onion won’t make you feel physically worse when you have a cold or the flu, but knowing you smell like onions certainly won’t make you feel better, either. Onions and garlic contain a high concentration of volatile organic compounds (VOCs), which give you bad breath and can also escape from your pores and into the air around you. 

What else could I try when I’ve got a cold or the flu?

Acetaminophen or ibuprofen. These are effective fever reducers and will also ease head and muscle aches. Take ibuprofen with food, though, because it can irritate your stomach. 

Stay warm and rest. Rest is important to healing, and it’s all about resource allocation. If your body is at rest, it can dedicate more of its energy to fighting a virus or healing. Also, cold viruses replicate more easily in a slightly cooler environment –studies in the U.S. and Australia found that infected cells die faster at core body temperature and RNAseL (an enzyme that attacks viruses) operates better at a higher temperature. 

Hydrate! Plain water, brothy soups, hot tea – these are your allies during a bout with a cold or flu. Good hydration can decrease nasal irritation when sneezing (or just breathing). Even being slightly dehydrated can increase a fever. If you’ve been vomiting or experiencing diarrhea, you’ll need to replace fluids even more. Even blowing your nose contributes to fluid loss when sick. Tea and soup have the added benefit of soothing a sore throat and making you feel cozy. 

Up your vitamin C and zinc. Some evidence indicates that vitamins and minerals like vitamin C and zinc may stimulate the immune system and potentially lessen the duration of your symptoms. Same with elderberry. Use care with zinc, though. Zinc nasal sprays can cause a permanent loss of smell in some people and zinc taken orally can result in a lingering metallic taste in your mouth.