Food poisoning cannot cause a rash. The symptoms, depending on the poisoning, more closely resemble a really bad bout of the cold and a stomach bug at the same time. You’ll typically experience diarrhea, vomiting, nausea, and cramping in the abdomen or thereabouts. Slightly more serious cases can include a low fever. The most serious cases involve intense dehydration, hives (depending on the poisoning culprit), and a high fever.
Often, you want to visit a doctor or the emergency room if you have diarrhea for more than three days, if you see blood in the stool, or a fever for two days that is at or above 100.4 degrees Fahrenheit. Other serious symptoms could include moderately bloody stool for more than two days and frequent, intense vomiting that lasts more than two days.