Food poisoning is the result of eating microbes or toxins in contaminated
food. Cases can affect one person or can occur as an outbreak in a group of
people who all ate the same contaminated food. While many cases are the result
of bacteria, some cases can be the result of poisonous components of plants and
animals. Food poisoning affects between 60 and 80 million people worldwide each
year, resulting in approximately 6 to 8 million deaths.
|Signs and Symptoms|
Food poisoning from bacteria causes nausea, vomiting, abdominal cramping, and
diarrhea. Specific bacteria may cause these signs and symptoms:
- Clostridium botulinum (C. botulinum, or botulism):
weakness, blurred vision, sensitivity to light, double vision, paralyzed eye
nerves, difficulty speaking, trouble swallowing, paralysis that spreads
downward, respiratory failure, death
- C. botulinum in infants: impaired physical growth (failure to
thrive), constipation, paralysis, sudden infant death
- Vibrio cholerae (V. cholerae, or cholera): stools that
are liquid with a whitish tinge
- Salmonella spp., Shigella spp., and Campylobacter
jejuni (C. jejuni): fever, chills, bloody diarrhea
- Escherichia coli (E. coli): hemorrhagic colitis (bleeding from
inflamed large intestine)
- Yersinia spp.: symptoms similar to appendicitis; delayed immune
reaction including arthritis and/or red, tender bumps under the skin (erythema
nodosum); sometimes bloody stool
Mushroom poisoning causes red blood cell problems, stomach flu, delirium
(confusion), vision difficulties, heart muscle problems, kidney failure, and
death of liver tissue. It causes death in about half of the people affected
unless treated right away.
Fish poisoning causes nausea, vomiting, diarrhea, abdominal pain, dizziness,
and headache. Specific types of fish can cause other signs and symptoms, such
- Scombroid poisoning: flushing (redness of the face and neck)
- Ciguatera toxicity: numbness or tingling around the mouth, feeling of
loose teeth, impaired touch sensation of hot as cold and cold as hot, itching,
muscle and joint pain, slow heart rate, low blood pressure; alcohol may cause
symptoms to recur or become worse
- Puffer fish poisoning: numbness or tingling around the mouth, trouble
coordinating movement, difficulty swallowing, excess saliva, twitching, loss of
ability to talk, convulsions, paralysis that spreads upward, respiratory
- Shellfish poisoning: numbness or tingling around the mouth or in the
arms and legs; trouble swallowing; difficulty speaking; death from anaphylactic
shock, a severe allergic reaction
|What Causes It?|
Usually bacteria, protozoans (such as amoebas), and algae cause food
poisoning. But sometimes poisonous parts of plants and animals are the
Common bacterial toxins include:
- E. coli in undercooked hamburger, unpasteurized apple juice or
cider, raw milk, contaminated water (or ice); can be spread from person to
- Traveler's diarrhea (another form of E. coli) from fruits,
leafy vegetables, unsanitary drinking water and ice made from this water, and
- Listeria monocytogenes (L. monocytogenes) in cole slaw, dairy
products (mostly soft cheeses from outside the United States), and cold,
- Salmonella spp. in poultry, beef, eggs, or dairy
- Shigella spp. from raw vegetables or from cool, moist
foods (such as potato and egg salads) that are handled after cooking
- Staphylococcus aureus (S. aureus) in protein-rich foods,
especially ham, eggs, custard-filled pastries, mayonnaise, and potato salad,
often from the hands of food handlers
- Bacillus cereus in uncooked grains, especially rice
- C. jejuni in raw milk and poultry
- C. botulinum in undercooked home-canned foods; in
children under 1 year of age, mostly from honey but also from corn
- Clostridium perfringens (C. perfringens) in meat and
poultry dishes and gravies, mostly foods that were cooked more than 24 hours
before eating and were not reheated well enough
- V. cholerae in bivalve (two-shelled) shellfish (such as
mussels, clams, oysters, and scallops), raw shellfish, and crustaceans (such as
lobsters, shrimp, and crabs)
- Yersinia in contaminated meats; less common in United States
than other food poisonings; more common in Scandinavia
Common types of fish poisoning include the following:
- Scombroid poisoning from bacteria in dark meat fish (tuna, bonito,
skipjack, mahi-mahi, mackerel) that are not refrigerated well
- Ciguatera poisoning in tropical fish (grouper, surgeonfish, snapper,
barracuda, moray eel) that have eaten the plankton Gambierdiscus
- Puffer fish poisoning from the organs and flesh of puffer
- Poisoning from bivalve shellfish that feed on red tide (plankton)
Mushroom poisoning occurs from eating wild poisonous mushrooms, especially
|Who's Most At Risk?|
Infants and the elderly are at greater risk for food poisoning. A person is
also at greater risk if any of the following is true:
- Pre-existing medical condition, such as chronic kidney failure or
- Antibiotic or histamine-blocking medicines
- Sickle-cell anemia and other problems with red blood cells
- Weakened immune system
- Travel in an area where contamination is more likely
- Food shortage
Listeriosis is most common in pregnant women, fetuses, and people with immune
problems. When a fetus is infected with L. monocytogenes, the fetus may
be born prematurely or die.
|What to Expect at Your Provider's Office|
Your healthcare provider will examine you for signs and symptoms of food
poisoning, such as stomach problems, and of dehydration. Your provider may also
ask about foods you have eaten recently. Tests of your vomit, blood, and stool,
and tests of any leftover food can identify the cause.
Your healthcare provider may also use these tests:
- Sigmoidoscopy (putting a thin, tube-like tool into the anus) to look
for bleeding or sores
- Electromyography (a test to measure electric impulses in the muscles)
to check for botulism
- Lumbar puncture (a test of fluid from the spine) for signs and
symptoms related to central nervous system
These steps can help prevent food poisoning:
- Be very careful to wash your hands and to clean any dishes or utensils
when you are making or serving food.
- Promptly refrigerate any food you will not be eating right
- If you take care of young children, wash your hands often and dispose
of diapers carefully so that bacteria can't spread to other surfaces or
- If you make canned food at home, make sure to follow proper canning
techniques to prevent botulism.
- Don't feed honey to children under 1 year of age.
- Don't eat wild mushrooms.
- When traveling where contamination is more likely, eat only hot,
freshly cooked food. Drink water only if it's been boiled. Don't eat raw
vegetables or unpeeled fruit.
- Always refrigerate fish well.
- Don't eat tropical fish caught during blooms of poison
- Eat puffer fish only in specially licensed restaurants with chefs
trained to cook it.
- Don't eat shellfish exposed to red tides.
If others may also have eaten a food that made you sick, let them know. If
you think the food was contaminated when you bought it from a store or
restaurant, tell the staff and your local health department.
Treatment is meant to help support recovery and relieve symptoms. For
instance, treatment may help replace fluids and electrolytes (such as sodium,
potassium, magnesium, and chloride), help the person breathe, or stop vomiting
or diarrhea. In most cases, healthcare providers do not prescribe antibiotics
because they may prolong diarrhea. If the person has eaten certain toxins (such
as from mushrooms or shellfish), the provider may take steps to empty and clean
out his or her stomach (a process called lavage) and administer activated
charcoal, which can absorb the remaining toxin.
Depending on the symptoms and the cause of food poisoning, a healthcare
provider may prescribe drugs including these:
- Antibiotics, such as ampicillin; similarly, TMP-SMX, doxycycline, or
ciprofloxacin, are given to prevent or treat traveler's diarrhea
- Antitoxin to neutralize toxins from C. botulinum
- Amitriptyline to control the numbness and tingling from ciguatera
- Apomorphine or ipecac syrup to cause vomiting and help rid the body of
- Atropine for mushroom poisoning
- Diphenhydramine and cimetidine for fish poisoning
- Mannitol for nerve-related symptoms of ciguatera poisoning
|Complementary and Alternative Therapies|
Animal studies have shown that certain vitamins and nutrients, such as
vitamin A and calcium, may be particularly effectively in protecting against
some food toxins while others, such as fish oil, may actually worsen the effects
of toxins. Milk thistle is an herb commonly used in Europe as a primary
treatment for mushroom poison. Homeopathy is particularly promising for the
treatment of diarrhea in children (which is sometimes caused by food poisoning)
in developing countries.
The following general nutritional guidelines may be helpful in the case of
- Drink plenty of fluids (to prevent dehydration)
- Drink barley or rice water (to soothe inflamed stomach or
- Lactobacillus acidophilus (for those taking
Advice more specific to food poisoning includes:
- Alpha-Lipoic Acid -- Several reports indicate that alpha-lipoic acid,
an antioxidant commonly found in broccoli, spinach, and beef, may be helpful in
the treatment of Amanita poisoning. The usual dose for the supplement
form is 50 mg twice a day or 100 mg once a day.
- Coumarins -- Lab studies have shown that coumarins, substances found
in many fruits and vegetables, may help stop the growth of E. coli. It is
not clear however, whether these test tube studies will translate into coumarins
offering a protective effect against E. coli infection in humans. To
prevent traveler's diarrhea, fruits and vegetables should be peeled, washed
carefully, and preferably cooked before ingestion (see section entitled
Many animal studies have investigated the use of vitamins, minerals, and
supplements to treat food poisoning. The most promising include:
- Vitamin A -- Rats infected with Salmonella appeared to
eliminate the bacteria from their bodies faster when pretreated with vitamin
A than with placebo, according to one study. They also gain more weight
and have a greater immune response than placebo-treated rats. Another study
suggests that vitamin A-deficient rats may actually be more prone to
- Calcium phosphate -- One animal study suggests that rats receiving
calcium phosphate supplements may be protected from infection by Salmonella
enteritidis poisoning. Researchers theorize that calcium phosphate helps to
defend against certain organisms found in some foods that can cause
- Fish Oil -- In a study of mice infected with the bacteria,
Listeria, animals that regularly consumed diets rich in fish oil had
significantly more bacteria in their spleens than animals that consumed diets
rich in lard or soybean oil. Until researchers can determine what these results
mean to humans, people who have Listeria infection should avoid foods
containing fish oil.
Use of the following for people with a specific food poisoning is well
- Milk Thistle (Silybum marianum) is one of the most effective
herbs for liver disorders and is widely used in Europe to treat Amanita
mushroom poisoning. Studies have shown that patients with Amanita
poisoning can be effectively treated with silibinin (the primary active
component of milk thistle) up to 48 hours after eating the deadly mushrooms.
Animal studies of Chinese and Japanese combination herbal remedies used for
L. monocytogenes support the traditional use for this type of food
poisoning. A few of the active ingredients include:
- Asian ginseng (Panax ginseng)
- Astragalus root (Astragalus membranaceus)
- Chinese cinnamon bark (Cinnamomum aromaticum)
- Ginger root (Zingiber officinale)
- Licorice (Glcyrrhizae glabra)
- Peony root (Paeonia officinalis)
- Skullcap (Scutellaria lateriflora)
When considering use of combination remedies, it is best to seek the advice
of an appropriately trained, licensed, and certified herbalist or traditional
Chinese doctor who will guide your individual treatment; the substances tend to
complement one another and work in tandem, not separately.
Laboratory studies (those performed in test tubes) suggest that the following
substances have activity against particular organisms that may cause food
- Bittervine (Mikania micranthu)
- A plant extract from a traditional Jamaican folk
medicine shows activity against several types of bacteria, including S.
aureus and E. coli.
- Tea Tree Oil (Melaleuca alternifolia) -- Lab studies have shown
that the essential oil of the tea tree has activity against E.
- Thyme -- The essential oil of thyme (Thymus vulgaris) has
killed the bacteria Salmonella typhimurium; additional lab studies
also suggest that thymol (a part of thyme oil) has activity against S.
While these lab results are interesting, they do not necessarily translate
into treatment for people, particularly the tea tree oil and thyme trials
because essential oils should generally not be ingested. Thyme is available in a
dried herb and is used to help digestion and to treat symptoms of gastritis
(inflammation of the stomach lining); however, it is not known whether the dried
herb would have the same activity as the oil against the bacteria mentioned.
- Barberry (Berberis vulgaris) has also been used traditionally
to treat diarrhea from infectious causes such as E. coli and V.
cholera and, therefore, may help ease this symptom in some people
with food poisoning.
In a recent study of children with acute diarrhea, those who received an
individualized homeopathic treatment for five days had a significantly shorter
duration of diarrhea than children who received placebo. Before prescribing a
remedy, homeopaths take into account a person's constitutional type. In
homeopathic terms, a person's constitution is his or her physical, emotional,
and intellectual makeup. An experienced homeopath assesses all of these factors
when determining the most appropriate remedy for a particular
- Arsenicum album — for foul-smelling
diarrhea from food poisoning or traveler's diarrhea with burning sensation in
the abdomen and around the anus; this remedy is most appropriate for individuals
who feel exhausted yet restless and whose symptoms tend to worsen in the cold
and improve with warmth; vomiting may also occur; Arsenicum may also be
used to prevent diarrhea when traveling
- Chamomilla — for greenish, frothy
stool that smells like rotten eggs; used primarily for children, especially
those who are irritable, argumentative, and difficult to console
- Calcarea carbonica — for children who
fear being in the dark or alone and who perspire heavily while sleeping; stools
have a sour odor
- Podophyllum —for explosive, gushing,
painless diarrhea that becomes worse after eating or drinking; exhaustion often
follows bowel movements and the individual for whom this remedy is appropriate
may experience painful cramps in lower extremities
- Sulphur — for irritable and weepy
children; may have a red ring around the anus and diarrhea with the odor of
Most food poisoning clears up on its own with no aftereffects. However, with
mushroom poisoning, as many as 50% of people die; with botulism, less than 10%
die. Some people may need help breathing for months afterwards. More than half
of poisonings from puffer fish are fatal. Death is rare in other fish
poisonings, but nerve-related symptoms can continue for months.
The following are some possible aftereffects of food poisoning:
- After shigellosis, white blood cell problems and kidney problems
- After E. coli infection, kidney problems and bleeding problems
- After yersiniosis, arthritis or tender bumps under the skin
- After botulism, long hospital stays (1 to 10 months) with fatigue and
difficulty breathing for 1 to 2 years or respiratory failure
- After C. perfringens infection, serious inflammation, bleeding,
and tissue death in the intestines
- After salmonellosis, Reiter's syndrome (an arthritis-like disease) and
inflammation of the heart lining
- After campylobacteriosis, Guillain-Barré syndrome (a nerve
For severe cases of food poisoning, the person may need to stay in the
hospital to receive fluids and electrolytes, and so healthcare providers can
monitor breathing. Providers may need to intubate the person (insert a tube down
his or her throat) or connect him or her to a machine to help with breathing.
Dialysis may be required. Cathartics (substances that help the body remove
waste), enemas, and lavage may help eliminate toxins.
Beers MH, et al. The Merck Manual: Diagnosis and Therapy. 17th
ed. Whitehouse Station, NJ: Merck Research Laboratories; 1999:285-292.
Blumenthal M, Goldberg A, Brinckmann J, eds. Herbal Medicine: Expanded
Commission E Monographs. Boston, Mass: Integrative Medicine Communications;
Bovee-Oudenhoven IM, Wissink ML, Wouters JT, Van der Meer R. Dietary calcium
phosphate stimulates intestinal lactobacilli and decreases the severity of a
salmonella infection in rats. J Nutr. 1999;129:607-612.
Duncan SH, Flint HJ, Stewart CS. Inhibitory activity of gut bacteria against
Escherichia coli 0157 mediated by dietary plant metabolites.
FEMS Microbiol Lett. 1998;164:238-288.
Facey PC, Pascoe KO, Porter RB, Jones AD. Investigation of plants used in
Jamaican folk medicine for anti-bacterial activity. J Pharm Pharmacol.
Fauci AS, Braunwald E, Isselbacher KJ, et al., eds. Harrison's Principles
of Internal Medicine. 14th ed. Vol. 1. New York, NY: McGraw-Hill;
1998:796-801, 876-880, 904-905.
Fritsche KL, Shahbazian LM, Feng C, Berg JN. Dietary fish oil reduces
survival and impairs bacterial clearance in C3H/Hen mice challenged with
Listeria monocytogenes. Clin Sci. 1997;92:95-101.
Gabriel EP, Lindquist BL, Abud RL, Merrick JM, Lebenthal E. Effect of vitamin
A deficiency on the adherence of fimbriated and nonfimbriated Salmonella
typhimurium to isolated small intestinal enterocytes. J Ped Gastroenterol
Gustafson JE, Liew YC, Chew S, Markham J, Bell HC, Wyllie SG, Warmington JR.
Effects of tea tree oil on Escherichia coli. Letters in Applied
Hatchigian EA, Santon JE, Broitman SA, Vitale JJ. Vitamin A supplementation
improves macrophage function and bacterial clearance during experimental
Salmonella infection. PSEBM. 1989;191:47-54.
Haubrich WS, et al. Bockus Gastroenterology. 5th ed. Philadelphia, Pa:
W.B. Saunders; 1995:1195-1210.
Hruby K, Csomos G, Fuhrmann M, Thaler H. Chemotherapy of Amanita
phalloides poisoning with intravenous silibinin. Hum Exp Toxicol.
Jacobs J, Jiménez M, Malthouse S, Chapman E, Crothers D, Masuk M, Jonas WB.
Homeopathic treatment of acute childhood diarrhea: results from a clinical trial
in Nepal. J Altern Complement Med. 2000;6(2):131-139.
Jonas WB, Jacobs J. Healing with Homeopathy: The Doctors' Guide. New
York, NY: Warner Books; 1996: 218-220.
Juven BJ, Kanner J, Schved F, Weisslowicz H. Factors that interact with the
antibacterial action of thyme essential oil and its active constituents. J
Appl Bacteriol. 1994;78:626-631.
Mandell GL, et al. Mandell, Douglas, and Bennett's Principles
and Practice of Infectious Diseases. 4th ed. New York, NY: Churchill
Murray PR, et al. Manual of Clinical Microbiology. 7th ed. Washington,
DC: ASM Press; 1999:356-359.
Rabbani GH, Butler T, Knight J, Sanyal SC, Alam K. Randomized controlled
trial of berberine sulfate therapy for diarrhea due to enterotoxigenic
Escherichia coli and Vibrio cholerae. J Infect Dis. 1987 May;155(5):979-984.
Rosen P, et al. Emergency Medicine: Concepts and
Clinical Practice. 4th ed. Vol. 3. St. Louis, Mo: Mosby;
1998:1931-1938, 2513-2516, 2178-2179.
Sabeel AI, Kurkus J, Lindholm T. Intensive hemodialysis and hemoperfusion
treatment of Amanita mushroom poisoning. Mycopathologia.
Taylor RB, et al. Family Medicine: Principles and Practice. 5th ed.
New York, NY: Springer-Verlag; 1998:812-815.
Ullman D. Homeopathic Medicine for Children and Infants. New York, NY:
Penguin Putnam; 1992: 75-77.
Ullman D. The Consumer's Guide to Homeopathy. New York, NY: Penguin
Putnam; 1995: 243-245.
Verma RJ, Shalini M. Ochratoxin A-induced cytotoxicity to human red blood
cells and its prevention by certain vitamins. Med Sci Res.
Yonekura K, Kawakita T, Mitsuyama M, Miura O, Yumioka E, Suzuki A, Nomoto K.
Induction of colony-stimulating factor(s) after administration of a traditional
Chinese medicine, xiao-chai-hu-tang (Japanese name: shosaiko-to).
Immunopharmacol Immunotoxicol. 1990;12(4):647-667.
Yonekura K, Kawakita T, Saito Y, Suzuki A, Nomoto K. Augmentation of host
resistance to Listeria monocytogenes infection by a traditional Chinese
medicine, ren-shen-yang-rong-tang (Japanese name: ninjin-youei-to).
Immunopharmacol Immunotoxicol. 1992;14(1-2):165-190.
|Review Date: December 2000|
|Reviewed By: Participants in the review process include: Jacqueline A. Hart, MD,
Department of Internal Medicine, Newton-Wellesley Hospital, Harvard University
and Senior Medical Editor Integrative Medicine, Boston, MA; Leonard Wisneski,
MD, FACP, George Washington University, Rockville,
Copyright © 2004 A.D.A.M., Inc
The publisher does not accept any responsibility for the accuracy of
the information or the consequences arising from the application, use, or misuse
of any of the information contained herein, including any injury and/or damage
to any person or property as a matter of product liability, negligence, or
otherwise. No warranty, expressed or implied, is made in regard to the contents
of this material. No claims or endorsements are made for any drugs or compounds
currently marketed or in investigative use. This material is not intended as a
guide to self-medication. The reader is advised to discuss the information
provided here with a doctor, pharmacist, nurse, or other authorized healthcare
practitioner and to check product information (including package inserts)
regarding dosage, precautions, warnings, interactions, and contraindications
before administering any drug, herb, or supplement discussed