In many pieces of fiction, vampires are cursed to only drink blood, finding normal food and drink indigestible. As a side-step around this restriction, many authors have used the idea of a vampire drinking the blood of an intoxicated person in order to get a buzz themselves. I always find it interesting when hobbies of mine intersect, and recently I found a nurse discussing this very idea, and my passing interest in medicine and long history with gaming collided.

Imagine sitting on a relaxing vacation beach, enjoying the plentiful sun and mai tais. A very intoxicated woman walks up to the bar and orders a shot, which she downs immediately. She then totters back to her table where she begins breastfeeding a newborn.

“Wait a second,” you may think, “alcohol is terrible for babies, everyone knows this!” You’re absolutely right – alcohol in the bloodstream of a fetus or small child can have all kinds of developmental effects. A pregnant mother who drinks shares her BAC (blood alcohol content) with the baby, which can cause real harm. However, when breastfeeding (or in our vampire’s case, drinking blood), the BAC doesn’t directly translate – their BAC becomes the drink’s ABV.

The California legal drinking limit is 0.08%; put simply, if 0.08% of your blood (8 hundredths of one percent) is alcohol, you are too impaired to drive, and that’s a measure of BAC. ABV is a measure of how alcoholic a particular drink is, with most beers fitting in the 4-5% range. How much would someone have to drink of a 0.08% ABV beer to start feeling its effects? For comparison, a glass of orange juice is around 0.5%.

Math time. If a glass of OJ is about 0.5% ABV, it would take about 6x glasses of blood (for a vampire) or breastmilk (for a baby) to equal the same alcohol content. Each glass of OJ is roughly 10% the ABV of a single beer. So to even feel the effects of a single beer, our drinker in this example would have to down … (doing some math) … about 60 glasses worth of source liquid.

The human body has around 5 liters of blood. A vampire would have to drink more than 30% of a rip-roaring drunkard in order to get even the most minute buzz, equal to one can of Budweiser.

The nurse I spoke with went on in much greater detail about how exactly blood could ferment, how the chains of protein would actually rot (if someone tried to bottle it), and other physical details the likes of which I will spare you. In short, there’s no reasonable way that a vampire can get drunk off of feeding.

Which means, not to worry, it’s even less possible for a baby to get tipsy from breastmilk.

Yay science!

Huge thanks to Seattle’s elisethegreat for her eerily knowledgeable take on this very odd question!