Intestinal infection: Symptoms, Causes & Treatment

Updated in June 2023

An intestinal infection usually emerges after consuming food or water that is contaminated with bacteria, parasites or a virus. It is associated with fever, abdominal pain, vomiting and frequent diarrhea. Intestinal infections occur most commonly in people with weaker immune system, like in children, adults or people with a history of chronic illness. 

In most cases, intestinal infections are treated conservatively with rest, hydration and light, easy-to-digest meals. Nonetheless, it is important to consult your doctor if your symptoms persist for longer than 3 days, or for longer than 2 days in children.

It is possible to prevent intestinal infections by maintaining good hygiene habits and making sure to prepare your food safely. You should wash your hands after using the bathroom, for example, and make sure you wash your vegetables well. 

Imagem ilustrativa número 3

Common symptoms 

Intestinal infection symptoms can emerge immediately after consuming contaminated food or water, or within 3 days of coming in contact with it. Symptoms depend on the type of microorganism, the severity of infection, your age and your general health status. 

The most common symptoms include:

  • Cramps and abdominal pain 
  • Constipation or diarrhea, with possible blood in the stool 
  • Vomiting
  • Headache 
  • Increased gas 
  • Loss of appetite 
  • Nausea
  • Fever 

It is important to remember that these symptoms can be more serious and concerning in children and older adults, as their immune systems are more fragile, making the spread of the microorganism easier. These populations are more at risk for weight loss and dehydration, which can lead to further complications. 

Main causes

Intestinal infections can occur due to the presence of microogranisms in food or water. The main microorganisms that can cause an intestinal infection include: 

  • Bacteria: Salmonella spp., Escherichia coli, Listeria spp., Bacillus cereus, Clostridium perfringens, Staphylococcus aureus;
  • Parasites: Giardia lamblia, Entamoeba histolytica, Toxoplasma gondii;
  • Viruses:  hepatitis A, rotavirus, norovirus.

People with a weaker immune system, like people with AIDS, people undergoing cancer treatment, children, pregnant women or older adults, have a higher chance of contacting an intestinal infection. 

In addition, people who have gastritis or heartburn, or who take medication to control stomach acid production (like omeprazole) are also at higher risk for contacting an intestinal infection, as they produce less stomach acid, making it more difficult to get rid of viruses and bacteria.

Treatment options 

Treatment for intestinal infections is aimed at relieving symptoms. Patients are advised to rest, drink plenty of fluids and eat light meals or snacks that are easy to digest, like cooked white rice, unseasoned white meat, and strained fruit juices. Read more about what to eat for diarrhea and which foods you should avoid. 

In addition, you should also avoid anti-diarrhea medication, as these can interfere with elimination of the infectious agent. Using these types of medications can prolong symptoms and lead to complications, which is why you should consult your doctor before taking any diarrhea medicine

In some cases, the doctor may prescribe medication, like antibiotics for bacterial infections or analgesics for abdominal discomfort. Probiotics may also be recommended to replenish bacterial flora and give the intestines an extra boost to treat the infection.

How to prevent an intestinal infection 

To prevent intestinal infections, it is important to partake in proper hand hygiene and food preparation measures. Examples include: 

  • Washing hands after using the bathroom or after touching pets 
  • Washing your hands before and after touching any food 
  • Avoid eating raw or undercooked meat or eggs 
  • Drink filtered or pre-boiled water

While you have symptoms, it is also important to avoid preparing food for other people, to prevent transmitting the infection to others. You should also avoid eating foods that can further irritate the bowels.