Gastroenteritis: Symptoms, Treatment, and First Aid Considerations

Gastroenteritis is an infection of the intestines that causes inflammation of the stomach and bowels. The severity can range from a mild stomach upset lasting one or two days to severe diarrhea and vomiting that persists for several days.

Gastroenteritis is commonly caused by viruses, but bacteria and other microorganisms can also be responsible. It spreads easily through contaminated food, water, surfaces, and close contact — making it common in childcare settings, schools, long-term care facilities, and households.

Common Signs and Symptoms

The main symptom of gastroenteritis is diarrhea, which is defined as:

• Loose or watery stools three or more times in 24 hours

• In some cases, stool may contain blood or mucus

Other symptoms may include:

• Vomiting (often lasting one day but sometimes longer)

• Abdominal cramping that may improve after a bowel movement

• Fever

• Headache

• Muscle aches and general fatigue

Vomiting often settles first, while diarrhea may continue for several days. Mild changes in bowel habits can last a week or longer before returning to normal.

Management and First Aid Care

In most cases, gastroenteritis improves on its own as the immune system clears the infection. However, dehydration is the most common and serious complication, particularly in young children, older adults, and individuals with chronic illness.

Increase Fluid Intake

• Fluids are the priority

• Adults should drink water frequently in small amounts

• Avoid sugary drinks, which can worsen diarrhea

• Oral rehydration solutions are recommended for:

  • Infants and young children

  • Adults over 50

  • Anyone who is frail or has underlying health conditions

Eating During Gastroenteritis

• It’s okay to stop eating briefly if nauseated

• Resume eating as soon as tolerated

• Start with light, bland foods such as:

  • Rice

  • Toast or whole-grain bread

  • Bananas

• Avoid spicy, fatty, or heavy foods until recovery improves

Medications

• Anti-diarrheal medications are not routinely recommended, especially in children
• For adults, loperamide may be used short-term to reduce frequent diarrhea when necessary (e.g., travel or work)
• Follow dosing instructions carefully and do not use for more than 5 days
• Do not use anti-diarrheal medication if there is blood in the stool or high fever unless advised by a healthcare provider

When to Seek Medical Care

Medical assessment is recommended if:

• Symptoms are severe or worsening
• Signs of dehydration appear (dry mouth, reduced urination, dizziness)
• Diarrhea or vomiting persists for several days
• Blood is present in stool
• The affected person is an infant, elderly, pregnant, or immunocompromised

Hospital care may be required if complications develop or fluids cannot be kept down.

First Aid & Training Disclaimer

This information is provided for educational and first aid awareness purposes only and is not a substitute for medical diagnosis or treatment.

St. Mark James Training, Canada’s largest 100% Canadian-owned and operated first aid and CPR training provider, teaches participants how to recognize dehydration, manage vomiting and diarrhea safely, and determine when urgent medical care is required.

To build practical skills and confidence, consider enrolling in Standard First Aid and CPR/AED, Emergency First Aid, or Childcare First Aid courses available across Canada through St. Mark James Training.