How Much Alcohol Causes A Hangover

Over the past two decades, researchers have learned quite a bit about hangovers. They’ve discovered that some types of alcohol are more likely to lead to hangovers than others, that neither dehydration nor blood sugar are causes of a hangover, and that a hangover tends to peak around the time a person’s BAC returns to 0. Similarly, towards the start of the 2010s researchers found that if a drinker hit a BAC of around 0.11%, then that person would likely end up with a hangover the next day. While the amount of alcohol required to reach that level varies by person, it did suggest that it might be possible to determine how much alcohol would cause a hangover for an individual person.

Unfortunately, this appears to be wrong. According to a recently completed study by Toast!’s scientific advisor, Dr. Joris Verster, part of the problem appears to have been the sample used to come to the 0.11% threshold. Many early hangover studies used university students for their samples, a population that tends to drink more than the average, and more than older groups. Recent studies using non-students as their samples have found that much lower BACs can and frequently still lead to a hangover the next day.

Instead, Dr. Verster and his colleagues found subjective intoxication (a fancy way of saying “how drunk someone feels themself to be”) is more predictive of a hangover than BAC. In short, the drunker you feel, the more likely you’ll have a hangover. There is a wide range of “tolerance” to alcohol among people, with everything from age, gender, weight, and other genetic factors (i.e. how quickly your body processes alcohol) playing a role, and it seems that “tolerance” matters. While an individual can drink up to their “tolerance” level, the amount they drink regularly, without substantial effect the next day, if they exceed that level they will drunker, and be more likely to have a hangover the next day. 

This is fairly reassuring in some ways. Rather than having to keep a BAC calculator handy to see if you might be risking a hangover, your subjective opinion is likely your best advice. If you’ve had a big night watching the game, but still feel fine and not all that drunk? You’re probably going to be fine in the morning. Feeling like those two glasses of wine hit a lot harder than you expected they would? Well, you may feel some pain come morning. So the next time you’re wondering if one more drink is going to cause a hangover tomorrow, just ask yourself “do I still feel pretty normal?” If the answer is yes, you’re probably fine. If you’re already feeling somewhat tipsy...well, that’s what Before You Drink gummies are for!