What are the symptoms of E. coli infection and when should you see a doctor?

Symptoms of E. coli infection typically appear 24 to 72 hours after exposure and include sudden, severe diarrhea that is often bloody, as well as abdominal pain and cramping, gas, loss of appetite, and, rarely, vomiting. You should see a doctor if symptoms do not improve within 5 days for adults or 2 days for infants and children, if symptoms worsen, if blood or pus appears in the stool, or if there are signs of dehydration.

Common Symptoms of E. coli Infection

Escherichia coli (E. coli) bacteria naturally live in the intestines of humans and animals. However, certain strains, such as O157:H7, can cause severe food poisoning [1]. Common symptoms of an E. coli infection include:

• Sudden, severe diarrhea, which is often bloody.
• Abdominal cramps and pain.
• Gas.
• Loss of appetite.
• Fever.
• Vomiting (rare).

These symptoms occur when E. coli bacteria enter the intestines and typically develop within 24 to 72 hours of exposure to the infection [1].

When Should You See a Doctor?

In most cases, people recover from common types of E. coli infections within a few days without specific treatment [1]. However, there are instances where visiting a doctor is necessary to assess the condition and receive appropriate care. You should contact your healthcare provider to schedule an appointment if you experience any of the following symptoms:

• Inability to keep fluids down.
• Diarrhea that does not improve within 5 days (2 days for infants and children), or if the diarrhea worsens.
• A child vomiting for more than 12 hours (for newborns younger than 3 months, contact a doctor immediately upon the onset of vomiting or diarrhea).
• Abdominal pain that does not subside after bowel movements.
• A fever higher than 38.3°C (101°F) for adults, or a fever higher than 38°C (100.4°F) accompanied by diarrhea in children [1].
• Presence of blood or pus in the stool.
• Symptoms of dehydration, such as decreased urination (or dry diapers in infants), excessive thirst, dizziness, or lightheadedness [1].
• Development of new symptoms.
• If you have recently traveled to a foreign country and have developed diarrhea [1].

Serious Complications Requiring Immediate Medical Attention

In some rare cases, E. coli infection can cause serious complications that require immediate medical attention. One such complication is Hemolytic Uremic Syndrome (HUS), a kidney condition that occurs when red blood cells are damaged and clog the kidney's filtration system [3]. Rare but severe symptoms of E. coli infection, which may indicate the development of HUS, include:

• Easy bruising.
• Pale skin.
• Red or bloody urine.
• Decreased urine output.
• Kidney failure [1].

Parents or caregivers should seek immediate care for a child experiencing any urgent symptoms such as unusual bleeding, swelling, extreme fatigue, decreased urine production, or unexplained bruising [3]. These complications can lead to acute kidney injury or severe anemia [1, 3]. To learn more about prevention and treatment, you can visit E. coli Infection: Prevention and Treatment (Arabic).

Diagnosis and Treatment

A healthcare provider will perform a physical examination, and a stool sample or similar tests may be conducted to confirm the presence of the disease-causing E. coli bacteria [1]. Treatment primarily aims to relieve symptoms and avoid dehydration. You may need to consume oral rehydration solutions to replace fluids and minerals lost due to vomiting and diarrhea [1]. In some severe cases, you may need intravenous (IV) fluids if you are unable to drink enough fluids or keep them down, which warrants a visit to a doctor's clinic or emergency room [1].

Medical references

• E. coli enteritis
• Hemolytic Uremic Syndrome in Children