Please help! what is the effects of dehydration and how long does it take for it to occur?

Dehydration: The effects of mild dehydration (D) are weakness and dizziness. More severe D effects are passing out. The time D takes to cause these symptoms is variable. If a patient has repeated nausea and vomiting, or excessive fluid losses, the time for symptoms to occur is more rapid than if the patient were merely denied access to fluids and how well hydrated the patient was before the D started.