Hello, Welcome to Health Care Magic. Thanks for writing. I am Dr.Saddiq ul Abidin. I have read your question completely, I understand your concern and will try to help you in best way possible. There are a number of mechanisms which can cause death in a person who has prolonged diarrhoea and vomiting. 1) Electrolyte imbalance: This can cause change in major electrolytes of boy like sodium and potassium , sodium imbalance can cause brain damage and potassium imbalance can cause heart to have abnormal contraction (arrhythmias) or even stop. 2) Dehydration: If patient loses water in diarrhoea and vomiting and doesn t take much water orally, patient can go into dehydration and this can go too far to even kill the patient. 3) Acid base imbalance: Vomiting can make patient lose acid and patient can go in acid base imbalance which can kill. 4) Direct effect of food poisoning: Some times the germ which causes foot poisoning is really dangerous and it can directly poison the patient to even cause death. A prolonged diarrhoea should never be neglected. You get 3-4 episodes or watery diarrhoea or vomiting, drink as much water with salts as you can and rush to the E.R I hope this answered your question.If you have more queries I am happy to answer.Otherwise rate and close the discussion Regrads. Dr.Saddiq ul Abidin M.B.B.S(Licensed Family Physician) Resident Medicine.