 [ Symptoms ] i have had gastroenteritis for three weeks now is this serious  i was diagnosed with the neuro virus i have had the symptoms for going on three weeks now i no longer had the diarrhea but still the nausea dizziness and stomach pain how long does this last do i have something to worry about i am tired of being sick [ Disease ] it can be very serious and gastroenteritis lasting more than a week really should be assessed by a physician most food poisoning will resolve in a healthy adult within a week if you go more than that you run the risk of throwing off electrolytes your body minerals salt potassium magnesium and so on you can suffer some cardiac events without the proper balance of minerals if you have bloody diarrhea this should always be assessed by physician blood in vomit could indicate an ulcer bowel movement with coffee grind look indicates digested blood ulcer or intestinal bleed 3 weeks i would call the doctor