 [ Symptoms ] i have fainted 3 times in almost a 3 year span does not drinking enough water cause that [ Disease ] yes dehydration and hypovolemic shock can cause fainting but first of all make sure that you are dehydrated in case if you still get recurring episodes of the same problem then you should consult a neurophysician and get a proper clinical examination done along with investigations like ct scan or mri to rule out the cause and treatment can be done accordingly hope this helps regards