• A. Mink

Hydration & Headaches

Ever heard of a dehydration headache, a headache brought on by a lack of hydration? I’ve heard of tension headaches, TMJ headaches (teeth grinding headaches) and migraines before, but dehydration headaches, not so much. It makes sense that when you’re dehydrated your muscles would hurt, right? Muscle cramps are commonly caused by dehydration, so why would it be any different for your brain? Let's look into how being dehydrated can lead to headaches.

Balancing the Body

Fluid intake is an essential part of maintaining the body’s internal balance. Being 73% water, our brains are especially sensitive to the effects of dehydration. Throughout the day, our body loses fluid from basic activities like exercising (through sweat) and using the bathroom. Fluid loss is natural. However, it becomes a problem when you lose fluid faster than the body can replenish it. Most experts recommend drinking between eight and eleven glasses of water a day to maintain an adequate liquid intake for functioning. But what happens when you fall a little short?

Dehydration Headaches

A dehydration headache is unique from other types of headaches as to their cause, pain localization and treatment.

Cause - Simply put, dehydration headaches are caused by an inadequate fluid intake. When you’re severely dehydrated your brain shrinks and this causes pain.

Pain Localization - As opposed to other types of headaches, dehydration headaches can affect the entire head and doesn’t cause pain in other areas (like the face, eyes or neck).

Treatment - Drink water and electrolyte-rich fluids after heavy exercise, after waking up in the morning, and before bed.


Dehydration headaches, like regular headaches, can cause acute or serious pain in the head depending on the level of severity. The most common symptoms leading up to and during a dehydration headache are:

  • Dry mouth

  • Extreme thirst

  • Bad breath

  • Radiating head pain

  • Sensitivity to light

  • Muscle cramps

  • Dizziness

Unlike other headaches, the treatment for dehydration headaches is simple: drink more water!

Instances of Dehydration Headaches

You’re most likely to experience a dehydration headache after one of two instances: after a long period of activity or a long period of rest. While that sounds contradictory, let me explain:

Activity-Acquired Dehydration Headache - Caused by long periods of activity where you aren’t replenishing fluids as you use them. Typically accompanied by muscle cramps or spasms. Could be considered a symptom of heat exhaustion or overwork.

Rest-Acquired Dehydration Headache - Caused by long periods of inactivity where you aren’t consuming fluids adequately (such as when sleeping.) Typically accompanied by dry mouth, extreme thirst and confusion. If you’ve ever had a long nap after using sleep medication and woke up with a headache, it was probably a dehydration headache.

Important Considerations

You’re more likely to get a dehydration headache in the summertime when temperatures are hotter, if you’re taking certain medications, if you’re older, or have certain conditions like diabetes.

In any case, we recommend getting those eight glasses of water in a day to avoid dehydration headaches and to stay healthy! Having less headaches could be as simple as drinking more water.


Blau JN, Kell CA, Sperling JM. (2004). Water-deprivation headache: a new headache with two variants. Headache. 44(1):79-83. doi: 10.1111/j.1526-4610.2004.04014.x. PMID: 14979888.

Spigt, M., Weerkamp, N., Troost, J., van Schayck, C., & Knottnerus, JA., (2012).A randomized trial on the effects of regular water intake in patients with recurrent headaches, Family Practice, 29(4) 370–375,

Spigt MG, Kuijper EC, Schayck CP, Troost J, Knipschild PG, Linssen VM, Knottnerus JA. (2005). Increasing the daily water intake for the prophylactic treatment of headache: a pilot trial. Eur J Neurol. 12(9):715-8. doi: 10.1111/j.1468-1331.2005.01081.x. PMID: 16128874.

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