It’s winter, which means it’s cold and flu season. And if your social media algorithm feeds you health and wellness content, you know that it’s also fire cider season. Does the “miracle in a bottle” concoction of apple cider vinegar, herbs, spices, garlic, and onions live up to proponents’ claims of boosting the immune system, lowering inflammation, treating heartburn, and so much more?

What is fire cider?  

Fire cider is a tonic (often homemade) prepared by steeping ingredients like onion, garlic, horseradish, jalapeno, ginger, turmeric, cayenne pepper, lemon, orange, and fresh herbs in unfiltered apple cider vinegar. But the recipe is highly adaptable to personal preference. As one influencer said, “There’s no wrong way to make fire cider.” (That begs the question: If each recipe is different, how is it that they all work? More on that in a moment.)

Let the brew sit for anywhere from two to six weeks, strain through cheesecloth, and you’ve got yourself a spicy, tart, pungent elixir.

What is fire cider good for?

If you’ve spent any time watching videos on Instagram or TikTok about fire cider, you may be wondering, what isn’t fire cider good for? Fire cider proselytizers claim not only that the tonic can boost the immune system and treat parasites, bacteria, and viruses, but you can also expect relief from heartburn and muscle and joint pain, a reduction in inflammation, balanced blood sugar, and improved heart health.

Perhaps unsurprisingly, no clinical trial has tested the health benefits of fire cider. While there is some limited evidence that drinking a tablespoon or two of vinegar before a meal can lower post-meal blood sugar levels, it’s not clear that any blood sugar benefit from vinegar extends beyond a single meal.

And don’t expect that fire cider will help tame heartburn. Why might it? Some people claim that heartburn is due to low—not high—amounts of stomach acid and that adding an acid (like vinegar) can help restore your stomach to baseline. But there’s no evidence to support that theory (or that any food triggers heartburn, for that matter). Rather, heartburn isn’t an acid problem. It’s due to a relaxed valve between the esophagus and stomach.

Beyond blood sugar and heartburn, nearly all the claims hinge on the assumption that the nutrients—like vitamins, minerals, antioxidants, and polyphenols—in fire cider’s ingredients end up in the final tonic. There’s no evidence that they do.

But even if they did, it’s unlikely that those nutrients would help prevent or treat colds, flus, or other infections. For starters, most studies show no fewer (or shorter) bouts of colds or flus when people are given extra nutrients like vitamin C, zinc, or vitamin D. Extra nutrients are likely beneficial only if you’re deficient in that nutrient—meaning, your blood levels are low enough to impair your body’s ability to function optimally. So don’t expect that drinking an extract made with garlic, ginger, oranges, or cayenne pepper will shore up your immune system.  

What’s more, the idea of “boosting” the immune system is flawed, because it doesn’t consider how the immune system works. Think of the immune system as a finely tuned machine, where each type of immune cell plays a unique role in fighting off invaders. An overall boost would make the immune system too reactive, tilting the system toward autoimmune disease—where the body attacks itself, not just invaders.

How should I drink fire cider?

Still want to try it? Fire cider enthusiasts often recommend downing a tablespoon or two of the cider daily. But undiluted vinegar can burn the esophagus and erode tooth enamel.  

And diluting it may not help your teeth. In one study, researchers randomly assigned 22 adults to take either a vinegar pill (which has almost no acid) or to drink two tablespoons of vinegar in one cup of water twice a day. After 8 weeks, tooth enamel eroded more in the vinegar drinkers than in those who took the vinegar pill. It's not clear if drinking diluted vinegar only once a day (or less) would also damage your teeth’s enamel, and it may be no worse than drinking other acidic drinks like soda or wine.  

If you enjoy drinking fire cider, your safest bet is to dilute one or two tablespoons in water and drink it through a straw. If you’d like to drink it as a hot tea by diluting it in warm water, drink it with a meal. That may help neutralize the acid’s harmful effects on your enamel.