E. coli (Escherichia coli) is a group of bacteria. Most strains live in your intestines (gut) and help with digestion, but some types can make you sick, causing food poisoning symptoms or infections.
Infections happen when harmful E. coli strains enter your body, usually through contaminated food, water, or surfaces. The bacteria can also spread through contact with people, animals, or objects that carry it, especially if you don’t wash your hands before touching your mouth.
You might ingest germs if you:
- Drink unpasteurized milk or juice
- Drink untreated or poorly treated water
- Eat raw dough or batter
- Eat undercooked meat
- Eat unwashed raw fruits or vegetables
- Swallow water from contaminated lakes, rivers, or pools
Risk Factors
Your chances of being exposed to E. coli infection increase if you:
- Caretake for someone with E. coli
- Touch contaminated medical equipment
- Don’t wash your hands after using the bathroom or changing a diaper
- Visit farms, petting zoos, or animal exhibits
You may be more likely to get seriously sick from E. coli if you:
- Are age 5 years or younger
- Are over age 65
- Have a weakened immune system
- Travel to areas with poor sanitation or unsafe water
Most E. coli strains are harmless and live in your intestines to help you digest food, make vitamins, and protect against harmful bacteria. However, some strains are pathogenic, meaning they can make you sick. Experts group E. coli by how each type causes illness and where it affects your body.
Some strains produce toxins or damage your intestinal lining, leading to diarrhea, while others cause different infections. These include:
- Enterotoxigenic E. coli: This kind is a leading cause of traveler’s diarrhea.
- Shiga toxin–producing E. coli: This common strain releases a toxin that can damage blood vessels in the intestines and kidneys, which can cause serious complications like kidney damage. It causes about 265,000 infections in the United States each year.
- Diffusely adherent, enteroaggregative, enteroinvasive, and enteropathogenic E. coli: These strains are less common, primarily affecting children or infants. They sometimes cause long-lasting or bloody diarrhea.
- Uropathogenic E. coli (UPEC): This type causes most urinary tract infections (UTIs).
Symptoms vary depending on the type of E. coli and where the infection occurs. You may notice:
- Digestive symptoms: Watery or bloody diarrhea, stomach cramps, nausea, or vomiting
- Urinary symptoms: Burning when you pee, frequent urges to urinate, cloudy or strong-smelling urine, and sometimes a fever
- Whole-body symptoms: Fatigue, fever, or signs of dehydration like dark urine, dry mouth, or dizziness
See a healthcare provider if your symptoms don’t improve within a couple of days, or if you have bloody diarrhea, a high fever, or symptoms of dehydration.
If you see a healthcare provider, they will usually ask about your symptoms, recent food or water exposure, and travel history. They may also ask if your diarrhea is watery or bloody, or if you have urinary symptoms or a fever.
A physical exam helps them check for dehydration, abdominal pain, or signs of a more serious infection. They may order tests to confirm the diagnosis or check for complications. Common diagnostic tests include:
- Blood tests: Some blood tests can measure how well your kidneys are working and check for signs of complications, including a low red blood cell count, low platelet levels, or high creatinine levels.
- Polymerase chain reaction (PCR): This method looks for specific genes in E. coli bacteria.
- Stool culture: This test checks a sample of your stool for harmful types of E. coli.
- Urinalysis: Also called a urine test, this test helps your doctor look for signs of infection, such as white blood cells, bacteria, or blood in your urine.
Most E. coli infections are mild and go away within a few days without medical treatment. The main goals of treatment are hydration (getting enough fluids) and managing symptoms.
Home Treatments
If your symptoms are mild, you can usually recover at home by getting extra rest and drinking plenty of fluids to replace what you lost through diarrhea or vomiting.
Check with your provider before taking anti-diarrheal medications, which may sometimes make your symptoms worse or increase the risk of complications.
Medical Treatments
If your infection is more severe, your doctor may recommend:
- Antibiotics: These are prescription medications to treat bacterial infections.
- Hospital care: Treatment at the hospital may be necessary for severe illness caused by E. coli, especially if you have kidney issues or other complications.
- Intravenous (IV) fluids: Your doctor may recommend administering fluids into a vein if you are severely dehydrated.
You can reduce your risk of E. coli by focusing on personal hygiene habits and food and water safety.
Personal Habits
Here are some personal habits to reduce your risk:
- Avoid eating raw dough or batter.
- Don’t swallow water while swimming in lakes, rivers, or pools.
- Drink milk or juice only if it’s pasteurized (heat-treated to kill germs).
- Use bottled or purified water for drinking and brushing your teeth when traveling or camping.
- Wash your hands regularly after using the bathroom, changing diapers, handling raw meat, or touching animals.
Food Preparation Safety Tips
You can also reduce your risk of E. coli by following these food safety steps:
- Cook ground beef, pork, and lamb to at least 160°F (70°C).
- Keep food away from areas where animals walk or poop.
- Let steaks and roasts rest for three minutes after reaching 145°F (62.6°C).
- Rinse fruits and vegetables under running water, even if you plan to peel them.
- Wash tools and surfaces that touch raw meat before using them for other foods.
Most E. coli infections go away on their own. However, in some people—especially young children, older adults, or those with weakened immune systems—the infection can cause complications. These may include:
- Hemolytic uremic syndrome (HUS): This rare condition damages blood cells and can lead to kidney damage or kidney failure.
- Sepsis: If E. coli enters your bloodstream, it can cause a life-threatening reaction.
- Severe dehydration: Ongoing diarrhea or vomiting can lead to severe fluid loss.
- High blood pressure or stroke: These can sometimes happen after recovering from HUS.
- Pneumonia: In rare cases, E. coli can cause lung infections, especially in people who are already very sick or in healthcare settings.
Most E. coli bacteria are harmless, but some strains can make you sick if you swallow contaminated food or water, or if you come into contact with germs from people or animals. You may have diarrhea, stomach cramps, or urinary symptoms.
Most E. coli infections go away on their own, but some can lead to serious complications. Knowing how E. coli spreads and how to protect yourself can help you stay safe.
