I don't need to say it, but I'll just say it — hangovers are the worst. After having a great night out with your friends, waking up with a headache or stomachache (or both) is about as big of a buzzkill as there is.

While you're lying in bed trying to will your headache away, you may start wondering: Where did I go wrong?

In the video above, Dr. Natalie Dryden, primary care physician at Houston Methodist, explains why hangovers happen, tips for preventing them and why hydration alone won't be enough to save you from your next one.