Early symptoms of food poisoning


The early symptoms of food poisoning may appear a few hours after ingesting contaminated food, although they may not surface for days or even weeks. Food poisoning is also known as foodborne illness, foodborne disease, or foodborne infection. Food becomes contaminated when bacteria, viruses, parasites, or their toxins find their way in at any point during processing or production, or if the food is not handled or cooked correctly at home. The signs of food poisoning vary depending on the source of the contamination. There have been over 250 different foodborne illnesses described, most of which are infections caused by food borne bacteria, viruses, and parasites, though a few are caused by noxious toxins or chemicals such as poisonous mushrooms.

As can be imagined, the spectrum of food poisoning symptoms is quite broad, but there are also certain signs that occur more often than not, including:

·         Nausea    

·         Vomiting    

·         Watery diarrhea    

·         Abdominal pain and cramps    

·         Fever

A mild case of food poisoning may last only a couple of hours and not amount to more than a temporary nuisance, but it can also result in illness, hospitalization, and even death. The contaminants that cause the most illnesses, hospitalizations, and death are:

·         Norovirus

·         Salmonella nontyphoidal

·         Clostridium perfringens

·         Campylobacter ssp.

·         Staphylococcus aureus

·         Toxoplasma gondii

·         e.coli (STEC) O157

·         Listeria monocytogenes

The foods that are more frequently linked with these and other pathogens can come from a single origin such as raw meat and poultry, raw eggs, unpasteurized milk, and raw shellfish, or from multiple sources, for example foods that combine the products of several individual animals like bulk raw milk, pooled raw eggs, or ground beef. As it turns out, a single hamburger, restaurant omelet, or glass of raw milk can contain meat from hundreds of animals, eggs from hundreds of chickens, or milk from hundreds of cows, respectively. Raw fruits and vegetables can also cause food poisoning, even when washed.

We’ve mentioned how the onset of early symptoms of food poisoning can vary from hours to days and weeks. Furthermore, each pathogen has an estimated time of arrival, so to speak, before the contaminated food is consumed.


Staphylococcus aureus

Clostridium perfringens



Clostridium botulinum


1-6 hours

8-16 hours

9-48 hours

12-48 hours

12-72 hours

24-48 hours





Vibrio vulnificus

Escherichia coli

Hepatitis A

Giardia lamblia

1-3 days

1-3 days

2-5 days

1-7 days

1-8 days

28 days

1-2 weeks

The time that it takes each contaminant to make its presence known inside the body is known as the incubation period. During that time, the pathogens pass through the stomach and into the intestine, where they bind to the cells that line the intestinal walls and start multiplying. Since most foodborne microbes cause diarrhea, cramps and nausea, it’s difficult to identify a particular contaminant without culturing stool samples or examining stools under a microscope, two diagnosing tools that are useful in detecting bacteria and parasites. Viruses are tougher to spot because they are very small for a light microscope and hard to culture, and usually require testing stool samples for genetic markers.

Unfortunately, cases of food poisoning are often underreported or misdiagnosed to the point that it is thought that there are 29 cases of salmonella for each one that is lab-confirmed. It is also believed that many hospitalizations and deaths by Salmonella are not properly verified. Therefore, it is wise to visit a doctor when one or more of the following takes place:

·         Frequent vomiting episodes that interfere with the ability to keep liquids down

·         Throwing up blood

·         Severe diarrhea that lasts longer than 3 days

·         Blood in stools

·         Severe pain or abdominal cramping

·         Oral temperature of 101.5 F or higher

·         Dehydration symptoms

·         Difficulty speaking or swallowing

·         Double vision

·         Downward-progressing muscle weakness


Dehydration is the most frequent serious complication of food poisoning, and infant and young children, elderly people, pregnant women, and people with chronic conditions like diabetes, liver disease, or AIDS are more susceptible to dehydration because their immune systems lose more fluids than they are able to replace. Dehydration can be deadly and its symptoms include:

·         Excessive thirst

·         Dry mouth

·         Little or no urination,

·         Severe weakness, dizziness or lightheadedness

A dehydrated person must be hospitalized and receive intravenous fluids. Other possible complications of food poisoning are miscarriage and stillbirth in pregnant women who have even mild cases of Listeria monocytogenes, and a condition called hemolytic uremic syndrome in older adults and children younger than five who develop cases of Escherichia coli.

There are many opportunities for food to become contaminated before it arrives at your table, and while several agencies like the CDC, the FDA, the USDA, and the National Marine Fisheries all work to ensure a proper handling of food, you the consumer must do your bit as well. For instance:

·         Wash hands, utensils and food surfaces on a very regular basis.

·         Keep raw foods and ready to eat foods separate.

·         Cook food at a safe temperature

-          Ground beef to 160 F (71.1 C)

-          Steaks and roasts to at least 145 F (62.8 C)

-          Pork to at least 160 F (71.1C)

-          Chicken and turkey to 165 F (73.9 C)

-          Fish is at 145 F (62.8 C)

·         Promptly refrigerate or freeze perishable foods

·         Defrost food properly

·         Throw suspicious food away.

It’s important for everybody to work together in order to avoid isolated cases of food poisoning as well as full-blown outbreaks. A food poisoning outbreak takes place when a group of people eat the same tainted food and become ill as a result. Detecting outbreaks helps to refine the food safety system and prevent future incidents. Therefore, if you realize that several people who were together at an event have all come down with the same illness, do not hesitate to report it to your local health department.

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