Food Poisoning

Food Poisoning


What is food poisoning?

Food poisoning (also known as food-borne illness) occurs when you eat or drink something that contains harmful germs (bacteria, viruses or parasites). Sometimes bacteria produce a toxin in food and it's the toxin that causes the problem.

How do you get food poisoning from fish?

There are two ways to get food poisoning from eating fish:

  • Ciguatera (say: “seeg-wha-terra”) poisoning: This happens when you eat a reef fish (any fish living in warm tropical water) that has eaten a certain poisonous food. This poison does not go away when the fish is cooked or frozen.
  • Scombroid poisoning: A substance called histamine builds up in some fish when they get too warm after they're caught. Histamine is a chemical that serves as a kind of alarm to let your immune system know that an infection is attacking part of the body. If you eat a fish that was not properly cooled after it was caught, you may react to the histamine that is released into your body.


What are the symptoms of food poisoning?

Symptoms of food poisoning can begin hours to days after consuming the contaminated food or drink. Timing depends in part on the cause of the food poisoning and the amount of food or drink consumed. Symptoms may include:

  • Abdominal pain
  • Diarrhea
  • Fever
  • Loss of appetite
  • Nausea
  • Vomiting
  • Weakness and fatigue

Food poisoning may affect just one person or a whole group of people exposed to the contaminated food or drink. It depends on how much of the germ or toxin each person consumed and how sensitive they are to it.

What are the symptoms of food poisoning from fish?

The first symptoms of ciguatera poisoning include abdominal cramps, nausea, vomiting and diarrhea. Symptoms can then progress to headache, muscle aches and skin that is itchy, numb or tingly. You may notice a change in your ability to feel hot or cold temperatures. For example, you may think something feels hot when it is actually cold.

Symptoms of scombroid poisoning will usually develop 20 to 30 minutes after you eat the affected fish. They can include flushing (turning red) of the face, nausea, vomiting, hives and abdominal pain. These symptoms are similar to other allergic reactions. However, getting scombroid poisoning does not mean you are allergic to fish.

Causes & Risk Factors

What foods are most likely to cause food poisoning?

Raw or undercooked meat or poultry, unpasteurized dairy products, raw shellfish, unwashed fruits and unwashed vegetables most commonly cause food poisoning.

Food poisoning is more common at picnics and buffets, where food (such as the mayonnaise in potato salad) is often left out of the refrigerator for a long time.

Who is at greater risk of getting food poisoning?

Children and the elderly are most likely to get food poisoning. You may also be at a higher risk if you:

Have recently traveled to areas outside the United States where you may have had greater exposure to germs that can cause food poisoning.


What should I do if I have food poisoning?

Most cases of food poisoning are mild and clear up in a few days. During that time, the goal is to prevent dehydration. Dehydration is the loss of fluids and electrolytes (nutrients and minerals) your body needs.

You should avoid solid foods and dairy products until the vomiting and diarrhea have passed. Once you are feeling better, ease into eating and drinking again. Try bland foods, such as crackers, toast and bananas. Avoid spicy foods, fried foods, dairy and foods that are high in fat and sugar. Drink plenty of fluids, but avoid milk or caffeinated beverages. Also, sports drinks (brand name: Gatorade, others) are not meant to be used to treat diarrhea and do not replace the body's electrolytes (salts and minerals) correctly to prevent dehydration.

When should I go to a doctor?

Make an appointment with your doctor if:

  • Severe diarrhea lasts for more than 3 days.
  • Frequent vomiting lasts for more than 2 days.
  • You see blood in your stool.
  • You are on diuretics and have diarrhea, nausea or vomiting.
  • You have a fever over 101°F.

Seek emergency care if:

  • Your stool is maroon or black or you see a lot of blood in your stool.
  • You are vomiting blood.
  • You are having trouble breathing.
  • You have severe abdominal pain or stomach cramping.
  • You have double vision or trouble moving parts of your body.
  • You have symptoms of severe dehydration (see the list above).
  • You have trouble swallowing.
  • You feel like your heart is pounding.
  • You have food poisoning from eating mushrooms or shellfish.

How is food poisoning from fish treated?

Ciguatera poisoning is treated with medicines that help ease your symptoms. There is no medicine that will cure ciguatera poisoning. The symptoms will go away on their own over time.

Scombroid poisoning is treated using an antihistamine (one brand name: Benadryl). An antihistamine is a medicine that blocks the histamine in your blood.

How long will I be sick?

The symptoms of ciguatera poisoning can last for 1 to 2 weeks. Exactly how long they last will depend on the amount of poison you have in your body. The symptoms can come back any time you eat an affected fish.

The symptoms of scombroid poisoning usually last for 24 hours or less. The symptoms can come back any time you eat fish that has not been refrigerated properly.

Ciguatera and scombroid poisoning are rarely fatal.

How do I know if I'm dehydrated?

Symptoms of dehydration include:

  • Little or no urine, or urine that is darker than usual
  • Dry mouth
  • Sleepiness or fatigue
  • Extreme thirst
  • Headache
  • Confusion
  • Feeling dizzy or lightheaded
  • No tears when crying

To treat mild dehydration, try taking frequent sips of water. Clear soups, clear sodas and juice mixed with water can also help. Avoid coffee, tea, dark sodas and other caffeinated drinks. These drinks can make dehydration worse. Give children who have mild dehydration water and/or an oral rehydration solution (ORS). An ORS (brands: Pedialyte, Ricelyte, Rehydralyte) contains the right mix of salt, sugar, potassium and other nutrients to help replace lost body fluids. You can buy an ORS at most grocery stores and drugstores.

Severe cases of dehydration may have to be treated in the hospital. You may be given fluids and electrolytes intravenously (through an IV).


Is food poisoning serious?

It can be. Dehydration can be dangerous, and so can certain types of food poisoning. Food poisoning caused by the Listeria bacteria can be very dangerous for the unborn babies of pregnant women. The infection is usually very mild for the mother, but can cause miscarriage, premature labor, stillbirth and developmental problems in their babies. People who have weakened immune systems are also at risk of developing complications from Listeria.

Food poisoning caused by Escherichia coli (E. coli) bacteria can cause hemolytic uremic syndrome (HUS). HUS can cause kidney failure, especially in people who have weakened immune systems.


How do I avoid food poisoning?

You can take a few simple steps to avoid food poisoning:

  • Wash fruits and vegetables thoroughly.
  • Clean countertops, cutting boards, knives and utensils before exposing them to different food items.
  • Wash your hands and utensils often.
  • Don't put raw and cooked meats on the same plate.
  • If knives have been used to cut up uncooked chicken, do not use them to cut up other ingredients that will not be cooked.
  • Cook meat thoroughly. Use a meat thermometer if needed and make sure beef is cooked to at least 160°F, chicken and other poultry to 180°F and fish to 140°F.
  • Don't use packaged food that has expired.
  • Throw away food in bulging or dented cans.
  • Refrigerate leftover food if it isn't going to be eaten within 4 hours.
  • Don't eat wild mushrooms.
  • Don't eat soft cheeses (especially imported) if you are pregnant or have a weak immune system.
  • When traveling abroad, don't eat raw fruits or vegetables that haven't been washed in an antimicrobial rinse and avoid unfiltered (or unboiled) tap water.
  • When at restaurants or social gatherings, avoid foods that have been left out of the refrigerator for long periods of time.

How can I avoid food poisoning from fish?

To avoid ciguatera poisoning, don't eat the fish that commonly carry the poison. This includes amberjack, grouper, snapper, sturgeon, king mackerel, barracuda and moray eel. The poison is more concentrated in a fish's internal organs, so you should never eat those parts of a fish.

To avoid scombroid poisoning, don't eat any fish that has not been refrigerated properly. Be especially careful when you eat fish such as tuna, sardines, mackerel, mahi-mahi or anchovies.

Questions to Ask Your Doctor

  • How do I know my symptoms are caused by food poisoning?
  • Are there medicines that prevent food poisoning?
  • Is food poisoning dangerous? When should I call you?
  • How is food poisoning different from other digestive disorders?
  • How long will it take me to recover from food poisoning?
  • Do I have food allergy?


Poisoning, Envenomation, and Trauma from Marine Creatures by RA Perkins, M.D., M.P.H. and SS Morgan, M.D. (American Family Physician February 15, 2004,