You need water to live. And if you’re hung over, you also need it to drown the demons that are assaulting your brain with spiky noisemakers. It’s the latter occasion on which you’re most likely to stand naked in front of your fridge, chugging water like a fever-ridden Neanderthal.

But despite how it feels at the time, you’re actually going about it all wrong.

When it comes to proper rehydration, Leonard Smith, gastrointestinal, vascular and general surgeon, advises, “You should sip water slowly, two to three ounces at a time, throughout the day. If you drink too fast, you risk diluting your blood, which may cause faster excretion of water by the kidneys.” Or in layman’s terms, if you drink water too quickly, it will cause your body to expel most of it as urine, which will have the effect of slowing the hydration process, i.e., the opposite of what you wanted to happen.

If you’re not hung over and you’re just trying to cleanse yourself and your kidneys by chugging water like this guy: Don’t risk it. There really is such a thing as water intoxication, known to doctors as hyponatremia. As per WebMD, it all boils down to sodium levels: “One of sodium’s jobs is to balance the fluids in and around your cells. Drinking too much water causes an imbalance, and the liquid moves from your blood to inside your cells, making them swell.” In the case of your brain cells, that’s seriously bad news.

Admittedly, you’d have to chug a lot of H2O for this to happen. To be exact, it would require drinking at least a gallon of water within the span of just a few hours for symptoms of hyponatremia to occur, according to one 2013 study. And in more extreme cases, where deaths from hyponatremia have occurred, the people involved had drunk 2.5 to 5.6 gallons of water in a similarly short space of time. “These are very isolated cases, and this is extremely rare,” says Dr. Sharon Bergquist, assistant professor of medicine at Emory University School of Medicine in Atlanta. “More people by far and away are dehydrated, [rather] than having a problem with overhydration.”

Even if you’re not, realistically, putting your life on the line by chugging water, though, you are reducing the effectiveness of your best possible hangover cure. So do your best to sip the pain away — your body will thank you.