Short answer: Maybe
Longer answer: If your body isn’t hydrated enough, it can definitely cause a headache. If that’s the case, water can definitely help. Even muscle tension (which is a notorious headache cause) can sometimes be eased by drinking water for the simple reason that your muscles function best when fully hydrated.
In a nutshell, it simply means that your body isn’t hydrated enough to function optimally. This deficiency can cause mild, moderate, or severe symptoms depending on how low on hydration you are. Some of those symptoms such as fatigue and low blood volume can cause headaches. Many people call this type of headache a dehydration headache. For ease of speaking, I use this term as well. To be clear, however, I’m not talking about clinical dehydration where your life is in danger.
Before I go on, I want to dispel two myths that just won’t die:
1) Headaches are NOT caused by a build up of toxins in the body. There are some substances, for some people, that can cause headaches but none of them falls under the vague category of toxin. They may, however, fall under the category of allergen, medication related effect, or substance withdrawal. Each of the items in these specific categories has associated physiological effects which are the actual cause of the headache.
2) Water does NOT flush toxins from your body. Your liver and kidneys are responsible for ridding your body of “toxins.” Yes, your kidneys need sufficient water in order to work properly, but you’ll develop other symptoms, like kidney stones, if they’re not getting the water they need to do their job properly.
A few tell tale signs that your body isn’t getting enough water are:
Not really. But there are a few considerations:
Will drinking water always help your headaches? No. Because they won’t always be caused by “dehydration.” But, even if it doesn’t help, drinking water won’t hurt you. And… if you simply have a good old fashioned tension headache, water may still help because you and your muscles function best when fully hydrated.
One closing thought for you: If you tend to get a lot of headaches that are relieved by water, you might want to be proactive and prevent them by just drinking more water in the first place.