Thank you to NHTSA for paying for this video.

Before we go any further, we want to remind you to drive sober. You probably already know the risks of driving drunk.

You could cause a crash, you could hurt someone, incur a lot of legal expenses, lose your job. Don't tell yourself it's not a big deal, ‘cause it is. So while we're going to be talking about how to maybe take the edge off your overindulgence, always, always drive sober -- or get pulled over. [♪ INTRO].

Raw eggs, black coffee, hot sauce --. I think it's a rule somewhere that hangover cures are 10% for the victim and 90% for the amusement of their friends. Because, let's be real, how could any of this actually work?

But there are things that proper doctors recommend to avoid or treat the symptoms of a hangover. Know your limits, stay hydrated, eat something -- it's mostly about using common sense before you start drinking. But what about those thousands of “cures” that people seem to tout?

Well designing an experiment to study hangovers is quite the challenge, but it turns out that there are a few treatments out there with some evidence to back them up. We all experience hangovers differently. Your age, sex, your body composition can all affect how your body metabolizes alcohol.

Genetics play a role, too. Genes seem to contribute almost half of the variability between people when it comes to hangover symptoms. Meaning you need to start with a diverse study population to account for all these differences.

What to give to test subjects can be complicated. Ethics boards frown on asking your participants to binge drink, for one thing. And what, if anything, you mix in with the alcohol can also have effects.

Like, maybe lab number 1 studies pure vodka, lab number 2 adds a little cranberry juice. Suddenly, the chemistry is totally different -- and that's nothing next to what you'd see out in the wild. This makes it hard to design a study that can both be consistently replicated, and actually mimics real-life drinking behavior.

And don't get us started on retrospective studies instead of controlled trials. That would mean asking people to give accurate accounts of their drinking behavior. There's a technical term that we're worried about here: it's called “Recall bias”.

All of this is to say that studying hangovers is tricky. So even if the evidence for a given hangover cure looks great in one study, it might not be reproduced by different researchers with different methods. That all said, there do seem to be preventatives or treatments that could head off or treat the worst symptoms, including some traditional tonics and everyday foods.

One small 2019 study asked hangover-sensitive drinkers about certain nutrients in their diets. They were interested in nicotinic acid, which comes from eating a lot of whole grains and mushrooms, and zinc, from foods like shellfish or legumes. And drinkers who reported consuming more of those nutrients also reported less severe hangovers.

But that's not so much a treatment as a thing that's already in your diet. And another caveat -- this was, in fact, a recall study. And most people don't necessarily remember how much zinc they ate yesterday.

As far as actual curatives, one thing that's gotten some attention is red ginseng. A small study from 2014 found that having men drink red ginseng relieved hangover symptoms compared to a placebo. A 2017 review of a handful of published studies also suggested that red ginseng could work as a treatment.

It also cited evidence for a handful of other items like. Siberian ginseng, Korean pear juice, and KSS formula, which is a traditional Chinese treatment that includes ginger, tangerine pith, and brown sugar. None of those treatments relieved all hangover symptoms, but they did seem to help some.

We don't yet know for certain how all these treatments might work — more investigation is needed. But they might reduce the oxidative stress on the liver that leads to cell damage. Or they might counteract immunological changes that may happen when drinking, like the increased production of signaling molecules that promote inflammation.

They also might affect the actual enzymes the body uses to break down alcohol, like alcohol dehydrogenase. There's actually some preliminary support for that last one too. A 2019 study looked at how over 50 types of food, including fruits, vegetables, cereals, spices, dairy products, as well as coffee and tea, affect the activity of those enzymes in a test tube.

They found that some foods, like sweet lime juice, seemed to enhance the activity of these enzymes, while others, like starfruit, seemed to decrease the activity. The scientists ultimately came up with a concoction of pear, sweet lime, and coconut water that enhanced the activity of the enzymes in the lab. Though having an effect in a test tube is a long way from actually doing anything in your body.

They ran a variety of formulas by a panel of tasters, who liked the pear/lime/coconut combo best. In the end, though, even if a hangover “cure” is developed, it might not affect people's drinking behavior much. In 2017, researchers asked a small survey of young people about how their drinking habits would change if they had access to a cure for hangovers.

The vast majority of social drinkers said they'd use such a product, but only a relatively small group — about 13% — said they'd drink more. Most people, the authors suggest, don't really consider hangovers when drinking, and don't necessarily want to get more drunk than they already do when they drink. What's more, a 2016 study showed that the severity of a hangover isn't significantly correlated to how much someone drinks, or even their highest blood alcohol concentration.

In the end, we definitely won't stop you from trying lime juice. We just can't pinky promise it'll work. Like we said, designing a hangover study is hard.

And because the methods vary so much, it's difficult to compare results between papers. But while the only 100% guaranteed way to avoid a hangover is to not drink in the first place, there do seem to be options better than your friend's coffee-egg-chili pepper recipe. Or at least better tasting.

And also like, just have an ibuprofen. Thanks for watching this episode of SciShow, and thanks again to NHTSA for paying for this video. Remember to always drive sober -- or get pulled over. [♪ OUTRO].