Headache
Among other symptoms, dehydration can present with dehydration headaches. Loss of hydration can alter the composition of the fluid lining the brain, the CSF. Headaches may also arise due to shrinking of the brain mass temporarily, owing to loss of hydration. Dehydration is the reason behind headaches seen after heavy drinking. Dehydration can serve as a trigger for migraine. It can be a throbbing, pulsating pain that can be localized to one side or may be diffused.