If you chug a glass of water the moment the pain starts, a dehydration headache usually fades within 1 to 3 hours. That’s the sweet spot for most people. But here’s the kicker: if you’re severely dehydrated—like, you’ve been running a marathon or hit the happy hour a little too hard—it can easily stretch to 6 to 8 hours. Yeah, your brain is basically a wet sponge, and when it shrinks, it pulls on tissues. Ouch.
Ever notice how these headaches love to pop up in the afternoon? That’s because your body’s been leaking fluids all day through sweat, breath, and bathroom breaks. If you wait until the headache is full-blown, you’re already behind the curve. Think of it like a fire alarm: you can’t just blow out the smoke; you need to find the fire source. Spoiler: the source is usually your empty water bottle.
