Symptoms may include headaches similar to what is experienced during a hangover, a sudden episode of visual snow, decreased blood pressure (hypo tension), and dizziness or fainting when standing up due to orthostatic hypo tension. Untreated dehydration generally results in delirium, unconsciousness, and in extreme cases death.
Dehydration is a condition and not a disease.
Not eating and passing out while driving are not symptoms of dehydration. Do you understand what dehydration is? It's an excessive loss of water from body tissue. It may follow prolonged fever, excessive diarrhea or vomiting, acidosis and in any condition in which there is a rapid depletion of body fluids.