We have found out that flu poisoning and flu are commonly mistaken for one another. That is why we have decided to compare each other with information from reliable sources. And we know that you already know a lot about the flu symptoms, so we are not going to bore you by retelling every detail. With no further ado, let’s start with their symptoms.


Food Poisoning

Food poisoning symptoms vary with the source of contamination, i.e. different germ that has caused the poisoning results in different symptoms. Most types of food poisoning cause some of the following signs and symptoms:

  • Nausea
  • Vomiting
  • Watery or bloody diarrhea
  • Abdominal pain and cramps
  • Fever

These signs and symptoms usually begin within hours after eating the contaminated food, but they may even begin days or weeks after. Sickness because of food poisoning usually lasts from a few hours to several days.


At first, the flu may seem like a common cold with a runny nose, sneezing and sore throat. Main difference between them is how fast they develop: colds usually develop slowly,  whereas the flu comes on suddenly.

Common signs and symptoms of the flu include:

  • Fever
  • Aching muscles
  • Chills and sweats
  • Headache
  • Dry, persistent cough
  • Shortness of breath
  • Tiredness and weakness
  • Runny or stuffy nose
  • Sore throat
  • Eye pain

Color-enhanced scanning electron micrograph showing Salmonella Typhimurium (red).

Causes of food poisoning:

Cross-contamination, which refers to the transfer of harmful organisms from one surface to another, is often the cause. This is especially alarming for ready-to-eat foods, such as salads or other produce. Since these foods aren’t cooked, harmful organisms aren’t destroyed before eating and can cause food poisoning.

Some germs make you sick within a few hours after you swallow them. Others may take a few days to make you sick. We are quoting from the Centers for Disease Control and Prevention, the list which contains some examples of the germs that cause food poisoning. The sequence is  in order of how quickly symptoms begin.

Staphylococcus aureus (Staph)
  • Symptoms begin 30 minutes – 6 hours after exposure: Nausea, vomiting, stomach cramps. Most people also have diarrhea.
  •  Common food sources: Foods that are not cooked after handling, such as sliced meats, puddings, pastries, and sandwiches.
Clostridium perfringens
  • Symptoms begin 6 – 24 hours after exposure: Diarrhea, stomach cramps. Vomiting and fever are uncommon. Usually begins suddenly and lasts for less than 24 hours.
  •  Common food sources: Beef or poultry, especially large roasts; gravies; dried or precooked foods
  • Symptoms begin 6 hours – 6 days after exposure: Diarrhea, fever, stomach cramps, vomiting
  •  Common food sources: Raw or undercooked chicken, turkey, and meat; eggs; unpasteurized (raw) milk and juice; raw fruits and vegetables
    Other sources: Many animals, including backyard poultry, reptiles and amphibians, and rodents (pocket pets)
  • Symptoms begin 12 – 48 hours after exposure: Diarrhea, nausea/stomach pain, vomiting
  •  Common food sources: Contaminated food like leafy greens, fresh fruits, shellfish (such as oysters), or water
    Other sources: Infected person; touching contaminated surfaces
Clostridium botulinum (Botulism)
  • Symptoms begin 18 – 36 hours after exposure: Double or blurred vision, drooping eyelids, slurred speech. Difficulty swallowing, breathing and dry mouth. Muscle weakness and paralysis. Symptoms start in the head and move down as severity increases.
  •  Common food sources: Improperly canned or fermented foods, usually homemade. Prison-made illicit alcohol.
  • Symptoms begin 1 – 4 days after exposure: Watery diarrhea, nausea. Stomach cramps, vomiting, fever, chills
  •  Common food sources: Raw or undercooked shellfish, particularly oysters

Color-enhanced scanning electron micrograph showing Campylobact.

  • Symptoms begin 2 – 5 days after exposure: Diarrhea (often bloody), stomach cramps/pain, fever
  •  Common food sources: Raw or undercooked poultry, raw (unpasteurized) milk, and contaminated water
E. coli (Escherichia coli)
  • Symptoms begin 3 – 4 days after exposure: Severe stomach cramps, diarrhea (often bloody), and vomiting. Around 5­­–10% of people diagnosed with this infection develop a life-threatening complication.
  •  Common food sources: Raw or undercooked ground beef, raw (unpasteurized) milk and juice, raw vegetables (such as lettuce), raw sprouts, contaminated water
  • Symptoms begin 1 week after exposure: Watery diarrhea, loss of appetite, and weight loss. Stomach cramps/pain, bloating, increased gas, nausea, and fatigue.
  •  Common food sources: Raw fruits or vegetables and herbs
  • Symptoms begin 1 – 4 weeks after exposure: Pregnant women typically experience fever and other flu-like symptoms, such as fatigue and muscle aches. Infections during pregnancy can lead to serious illness or even death in newborns.
    Other people (most often older adults): headache, stiff neck, confusion, loss of balance, and convulsions in addition to fever and muscle aches.
  •  Common food sources: Queso fresco and other soft cheeses, raw sprouts, melons, hot dogs, pâtés, deli meats, smoked seafood, and raw (unpasteurized) milk. 

As you can see, even though flu and food poisoning symptoms are very alike, they are very different from each other. Commonly you can differentiate each other by bloody diarrhea, it is more likely to be a symptom for food poisoning. Surely their causes are much more different than each other, unless you have an electron microscope at home, it is not very easy to tell the difference. But you can always check your upper respiratory tract illnesses via FluAI. Until next week, please try and stay away from raw foods, at least those not very clean.

For more information about flu causing virus influenza:



The link of the list for the food poisoning causing germs:

Mayo Clinic Staff. (2020, June 26). Food poisoning. Retrieved November 11, 2020, from https://www.mayoclinic.org/diseases-conditions/food-poisoning/symptoms-causes/syc-20356230 

NHC (n.d.). National Health Service. Retrieved November 11, 2020, from https://www.nhs.uk/conditions/food-poisoning/ 

Flu Symptoms & Diagnosis. (2020, August 31). Retrieved November 11, 2020, from https://www.cdc.gov/flu/symptoms/index.html 

Image Links:




Elif Başak Alço


Related Post

Leave a Comment