Signs and Symptoms of Food Poisoning

Food poisoning is a condition that occurs from consuming contaminated foods or beverages. The foods or beverages contain bacteria, viruses, or parasites that can multiply in the body. Common bacterial sources of food poisoning include Salmonella, E. coli, and Listeria.

Up to 30% of people in industrialized countries (including Canada, Japan, Australia, New Zealand, the United States, and 18 European countries) experience food poisoning every year. Food poisoning causes symptoms like vomiting, nausea, fever, and cramping. Symptoms might start within a few hours of eating contaminated food or up to one week later. They can last from about 24 hours to about one week.

Food poisoning usually resolves on its own with time and at-home remedies. However, some people may experience dehydration, which can worsen symptoms.

Common Symptoms

True to its name, food poisoning causes bacteria to release toxins into your body, which can make you feel very ill. Symptoms of food poisoning closely resemble those of stomach flu, which is the result of a viral illness.

Nausea is a common symptom of food poisoning. You may feel so nauseous that you do not want to eat or drink anything.

Other common food poisoning symptoms include:

• Diarrhea, which may have streaks of blood present
• Vomiting
• Abdominal pain or cramping
  
• Fever
• Headache

Symptoms in infants and children include:

• Change in mental state, such as increased irritability
• Lack of energy
• Diarrhea that lasts more than 24 hours
• Frequent loose stools or vomiting
  

Dehydration Symptoms

It's important to recognize symptoms of food dehydration, as this can result from food poisoning due to vomiting, diarrhea, fever, or because you feel too sick to drink.

Dehydration symptoms include:

• Severe thirst
• Dry mouth
• Dry skin
• Urinating or sweating less than usual
• Darker-colored urine
• Fatigue
• Dizziness
  

Severe Symptoms

You may experience more severe food poisoning symptoms that indicate the need to seek immediate medical attention.

These symptoms include:

• Mental status changes, such as confusion
• Six or more episodes of diarrhea in a day
• Diarrhea that lasts more than three days
• Inability to keep liquids down due to frequent vomiting
• Severe abdominal or rectal pain
• Black, tarry stools
• Fever that exceeds 102 degrees

Severe dehydration symptoms include:

• Rapid breathing or heartbeat
• Lack of urination
• Confusion
• Fainting
  

Rare Neurological Symptoms

Different toxins can cause food poisoning. Some can cause nervous system symptoms in addition to stomach-related ones. These conditions are a rare occurrence but can cause serious symptoms. Examples include food poisoning due to shellfish toxicity or botulism.

Botulism is a serious illness caused by a toxin from the bacterium Clostridium botulinum, which is found in soil. It can be caused by eating food contaminated with the toxin or when an infected wound makes the toxin. It often occurs after eating fermented foods or foods that weren't canned properly, especially low-acid foods like green beans, beets, and potatoes.

Head-related symptoms, like headaches and blurred vision, generally appear first. Symptoms then start to move down to limb muscle weakness. You will probably experience these symptoms about 18 to 36 hours after you eat contaminated food.

Symptoms of botulism include:

• Headache
• Skin tingling or numbness
• Weakness
• Double or blurred vision
• Ptosis (drooping eyelids)
• Slurred speech
• Paralysis
  

Nervous system-related symptoms of food poisoning can be seriously and potentially deadly. They require immediate medical attention. Healthcare providers can treat conditions like botulism with a medication called Botulinum Antitoxin, Heptavalent (antitoxin), but it's important to seek treatment as soon as possible.

Symptoms in Children

Children account for about 40% of food poisoning cases. Food poisoning can be dangerous for children because they can experience more severe illness. Infants and children under 5 years old do not have fully developed immune systems. As a result, they are less capable of fighting off bacteria that commonly cause food poisoning.

Food poisoning symptoms in infants and children are often similar to symptoms in adults. You may see symptoms like:

• Diarrhea
• Nausea
• Stomach pain
• Vomiting

More severe symptoms for infants and young children include:

• High fever
• Severe abdominal or rectal pain (pain around the anus or rectum, the area of the large intestine closest to the anus)
• Black and tarry stools
• Stools with blood or pus

They also might complain of nervous system symptoms, such as headache, blurred vision, or skin tingling or numbness.

Dehydration related to food poisoning can cause different symptoms in infants and children, such as:

• Dry mouth or tongue
• Tearless crying
• No wet diapers for at least three hours
• Significant sleepiness or drowsiness
• Irritability
• High fever

If your infant or child experiences these symptoms, seek immediate medical attention. Children younger than 5 years old are three times more likely to be hospitalized with Salmonella food poisoning.

Infant Botulism

Infants can get botulism from eating bacteria spores in soil or honey. This is why babies under the age of one should not eat honey in any form.

Signs of infant botulism require immediate medical attention. Symptoms include:

• Weak or altered cry
• Lack of facial expression
• Constipation
• Lack of interest in feeding
  
• Pupils that don't respond normally to changes in light
• Ptosis (drooping eyelids)
• Breathing difficulty

When To See a Healthcare Provider

Severe food poisoning or dehydration symptoms warrant a trip to see your healthcare provider. An estimated 128,000 people are hospitalized each year due to severe food poisoning symptoms.

You should also seek medical attention if you are unable to keep food or fluids down over a period of several days, or if you're pregnant.

Infants and children younger than 5 years old are at a higher risk of getting food poisoning and exhibiting more severe symptoms, as are adults over the age of 65, pregnant people, and people with weakened immune systems.

A Quick Review

Food poisoning symptoms can occur almost immediately after you eat contaminated food or up to about a week later, depending on the cause of food poisoning. While many symptoms are similar for adults and children, infants and young children might show different symptoms.

Symptoms like diarrhea, nausea, and vomiting usually resolve within a few days. However, if you experience more severe symptoms or symptoms of dehydration, you may need to seek medical attention. Nervous system-related food poisoning symptoms, such as blurred vision, muscle weakness, or paralysis, require immediate medical attention.