Symptoms vary depending on what is causing the illness. They may begin within a few hours or a few weeks depending on the cause. Common symptoms are:  Upset stomach. Vomiting. Diarrhea. Diarrhea with bloody stools. Stomach pain and cramps. Fever. Headache.  Less often food poisoning affects the nervous system and can cause severe disease. Symptoms may include:  Blurred or double vision. Headache. Loss of movement in limbs. Problems with swallowing. Tingling or numbness of skin. Weakness. Changes in sound of the voice. 
symptoms vary depending causing illness  may begin hours weeks depending cause  common symptoms are:  upset stomach  vomiting  diarrhea  diarrhea bloody stools  stomach pain cramps  fever  headache   food poisoning affects nervous system can cause severe disease  symptoms may include:  blurred double vision  headache  loss movement limbs  problems swallowing  tingling numbness skin  weakness  changes sound voice
food poisoning