The flu is a very contagious respiratory illness caused by the influenza virus, while food poisoning is commonly caused by infectious bacteria, notes WebMD. Additional differences include how transmission occurs and the symptoms caused by each illness.
Food poisoning is caused by over 250 different diseases, according to WebMD. One common type of food poisoning, caused by campylobacter infection, includes side effects such as diarrhea, which can be bloody; nausea and vomiting; fever; and abdominal pain. The flu causes symptoms such as a high fever, body aches, weakness and fatigue. Chest discomfort, coughing and headaches can also occur with the flu.
One type of food poisoning, caused by salmonella, can occur when a person drinks unpasteurized milk or eats undercooked poultry, explains WebMD. Eating undercooked eggs can also cause salmonella food poisoning. The flu is spread from person to person mainly by droplets from coughing, sneezing or talking, states the Centers for Disease Control and Prevention. Not as frequently, the flu is spread when an infected surface or object is touched. Another difference between the two illnesses is bacterial infections that cause food poisoning can be treated with antibiotics, while the flu virus must be treated with an antiviral medication, says WebMD. Both food poisoning and the flu can lead to life-threatening complications.