Onion tea is made by simmering quartered onions in water for about an hour, then straining the liquid and drinking it warm. It’s a traditional home remedy often used during cold and flu season, and it takes almost no effort to prepare. Here’s how to make it, which onions work best, and what you’re actually getting out of it.
Basic Onion Tea Recipe
Start with 2 medium onions and 4 cups of water. Quarter the onions but leave the papery outer skin on, as the skin contains a high concentration of antioxidant compounds. Place the onions in a pot, add the water, and bring everything to a boil over medium heat. Once it reaches a boil, reduce the heat and let it simmer for about an hour. The long simmer draws out flavor and plant compounds into the liquid.
After an hour, strain the tea through a fine mesh strainer and discard the onion pieces. You’ll have a golden, savory broth that can be sipped warm from a mug. This recipe makes roughly 2 to 3 cups once the water has reduced during simmering. You can store leftovers in the refrigerator for up to three days and reheat as needed.
Which Onion Variety Works Best
Yellow onions are the most common choice and produce a mildly sweet, well-rounded tea. But if you’re making onion tea specifically for its antioxidant content, your choice of onion matters more than you’d expect. Quercetin, the plant compound most associated with onion’s health properties, varies dramatically between varieties. Chartreuse (light green-yellow) onions contain the highest concentration, roughly four times more quercetin than red onions on a dry-weight basis. Yellow onions fall in between, with particularly high levels of a form of quercetin that dissolves more easily in water.
Red onions are still a solid option and will give your tea a slightly deeper, more pungent flavor along with a rosy tint. If you can find organic onions, use those, especially since you’re simmering them with the skins on.
Making It Actually Taste Good
Plain onion tea is savory and mild, but it won’t win any flavor awards. A few simple additions can transform it into something you’ll genuinely want to drink.
- Honey: A tablespoon per cup rounds out the sharpness and adds sweetness. Add it after the tea has cooled slightly, since very hot liquid breaks down some of honey’s beneficial enzymes.
- Fresh ginger: Slice a thumb-sized piece of ginger and add it to the pot during the last 15 to 20 minutes of simmering. Ginger adds warmth and a spicy bite that pairs naturally with onion.
- Lemon juice: A squeeze of fresh lemon brightens the flavor and adds vitamin C. Stir it in after straining.
- Garlic: Toss in 2 or 3 whole crushed garlic cloves with the onions for a more robust, savory version that leans closer to a healing broth.
Combining all four, ginger, honey, lemon, and onion, is a popular variation that tastes surprisingly good and is easier to get down than plain onion water.
What’s Actually in the Tea
One medium onion contains about 8 mg of vitamin C, along with potassium, folate, and vitamin B6. Potassium supports fluid balance and muscle function, while vitamin C plays a role in immune function and iron absorption. Two onions simmered together will release a portion of these nutrients into the water, though not all of them transfer fully during cooking.
The compound that gets the most attention is quercetin, a plant-based antioxidant with anti-inflammatory properties. Here’s the catch: quercetin dissolves poorly in water at normal temperatures. At 25°C (room temperature), its solubility is only about 2 parts per million. Boiling increases extraction significantly, but as the tea cools, a large fraction of those compounds can fall out of solution and form a precipitate, the cloudy sediment that settles at the bottom of your cup. At typical simmering temperatures, only about 40% of the quercetin extracted remains dissolved once the liquid cools. Quercetin glycosides (a naturally occurring form found in onion flesh) dissolve somewhat better than pure quercetin, which is one reason using the whole onion, not just the skin, still contributes meaningful amounts to your tea.
If you see sediment at the bottom of your cup, give it a stir before drinking rather than leaving it behind. That cloudiness contains a significant share of the extracted plant compounds.
Does It Help With Colds?
Onion tea is widely used as a folk remedy for coughs and congestion, and you’ll find it recommended across cultures. The reality is more modest than the reputation. There is no definitive clinical evidence that onion water alleviates respiratory symptoms caused by colds or flu. The strong sulfur compounds in onion can make your eyes water and temporarily loosen nasal congestion, but that effect is brief and doesn’t mean your body is healing faster.
That said, sipping any warm liquid during a cold has genuine benefits. Warm fluids help thin mucus, soothe irritated throat tissue, and keep you hydrated. Onion tea with honey, ginger, and lemon delivers all of those basic comforts while adding some vitamin C and antioxidants on top. It’s a reasonable home remedy, just not a proven medicine.
Side Effects to Know About
Onion tea is safe for most people in normal amounts, but it can cause stomach discomfort. The most common complaints are heartburn and gas, particularly if you drink it on an empty stomach or in large quantities. People with acid reflux or chronic indigestion may find that onion tea makes symptoms worse rather than better.
If you’ve had certain intestinal surgeries, particularly procedures involving a pouch near the anus, onion in any form can increase gas and discomfort. Onion also has mild blood-thinning and blood sugar-lowering properties. For everyday tea drinking, this is unlikely to matter, but if you’re scheduled for surgery, it’s worth stopping onion tea at least two weeks beforehand to avoid any interference with clotting or blood sugar management during the procedure.
Start with one cup a day if you’ve never tried it, and see how your stomach responds before making it a regular habit.