Why when you don’t drink enough water it gives you a headache



Why when you don’t drink enough water it gives you a headache

In: Biology

Its your body telling you to drink water, just like hunger is your body telling you to eat and pain is your body telling you that you were damaged. Your body constantly measures your blood pressure and osmotic values so it knows when it needs water.

The same reason why your stomach may rumble when you are hungry, your body is trying to tell you there is a scarce amount of this available to it which is why you should supply it with more

This is interesting to me. Reading up on this I looked at the “international classification of headaches disorders” manual, which is over 200 pages long, and lists over 300 types of headache. And guess what is not mentioned as a headache type? Dehydration!


As for published, peer reviewed literature on the subject, there is:

a 34 person study, that postulated maybe dehydration headaches exist (https://pubmed.ncbi.nlm.nih.gov/14979888/)

And a study that could not determine if increasing water intake reduced headaches. ( https://www.researchgate.net/publication/280392526_Increased_water_intake_to_reduce_headache_Learning_from_a_critical_appraisal)

An literature review saying there is no evidence of causal link between headache and dehydration (https://academic.oup.com/nutritionreviews/article/73/suppl_2/97/1930742)

An article saying fluids did not help headaches (https://emj.bmj.com/content/37/8/469)

But google dehydration headaches and there are hundreds of links talking about dehydration headaches…

So while there are plenty of reasons why dehydration could cause a headache (salt levels in the blood, toxins in the blood not flushing away, low blood pressure) I cannot find (reasonable) primary evidence that dehydration is a cause of headache, or that drinking water helps with headache.

Why when you drink too MUCH water you get a hardache?