Does Coffee Actually Cause Dehydration? Here’s The Real Deal With That

Enjoy coffee? Of course you do. But, you might have avoided that second cup this morning based on a myth we’ve all believed for way too long. Due to its level of caffeine, it makes sense to believe that coffee dehydrates you, causing symptoms like dry skin and headaches. But it’s not actually true.

The idea came about back in 1928, according to LiveScience. Due to causing increased urination, coffee and other caffeinated beverages were said to be diuretics. That’s still accurate — but even though these beverages cause humans to lose water, it doesn’t necessarily mean they’re losing hydration. “[T]he truth of the matter is, a small increase in urine output has little to do with dehydrating the body,” Lawrence Armstrong, who works at the Department of Kinesiology at the University of Connecticut, told LiveScience.

Armstrong himself put the myth to the test in his own study, which controlled the diets and caffeine levels of 59 men for 11 days. Some of the men studied were given caffeine by way of capsule, and were monitored to get a sense of urine output and overall hydration. As it turns out, their levels weren’t any different than the control group. It was also found that both small and large doses of caffeine had the same effect, meaning that if dehydration was actually a factor, both one cup and five cups would do the same damage.

In case you were curious, Armstrong also talked about how much coffee it would take to cause an overdose — which is a topic that you’re probably curious about if you find yourself reaching for that fifth cup of coffee every day.

As Armstrong stated, there’s a reason why you don’t see people hospitalized for overdoing it on one of America’s most popular (and legal) drugs — it takes awhile to get to that point. Think 100 cups of coffee per day.

If you were blaming dehydration for why you get headaches after drinking coffee, Marie Claire points out that it might actually be your own caffeine sensitivity. It’s important to listen to your body, so make sure to keep tabs on whether a certain amount, or even certain brand, might trigger a reaction.

Sure, the best beverage to down for your health is water, but it’s still good to know that a cup of coffee (or three) every morning isn’t going to cause too much harm.

Looking for a way to use that leftover splash of coffee in the morning? The next time you’re making cake or brownies, add any remaining coffee you have into the batter. Your cake won’t taste like coffee, but it’ll be more moist and coffee really makes the flavor of chocolate pop.