Dehydration headaches are similar to regular normal headaches so it can be hard to tell if the headache is being caused by dehydration.
Although a dehydration headache is typically a dull headache or the dehydration headache can be an intense migraine headache that won't go away or gets worse.
Also with a dehydration headache you may not feel any pressure or facial pain when you do have the dehydration headache.
If you are dehydrated and haven't drank anything in awhile you should drink some water or something to hydrate yourself.
If you stay dehydrated you can pass out and die.
So always drink water or something to hydrate yourself before you feel thirsty.
If you're severely dehydrated then you need an IV from the hospital to get hydrated.