Most cases of diarrhea are caused by germs you swallow, whether from contaminated food, unsafe water, or hands that picked up bacteria or viruses along the way. That means prevention comes down to a handful of practical habits: washing your hands well, handling food safely, drinking clean water, and staying up to date on vaccines for young children. Here’s how each of those works in practice.
Handwashing Makes the Biggest Difference
Consistent handwashing with soap reduces diarrheal illness by 23 to 40 percent across communities. That’s a remarkable return on something that takes 20 seconds. The key moments are before preparing or eating food, after using the bathroom, after changing a diaper, and after touching animals or their waste.
Technique matters more than most people realize. Wet your hands, lather with soap (including the backs of your hands, between your fingers, and under your nails), scrub for at least 20 seconds, then rinse and dry with a clean towel. If soap and water aren’t available, an alcohol-based hand sanitizer with at least 60 percent alcohol works against many pathogens, though it’s less effective against certain viruses like norovirus when hands are visibly dirty.
Cook Food to Safe Temperatures
Undercooked meat and eggs are among the most common sources of bacteria that cause diarrhea. A food thermometer is the only reliable way to know your food is safe. Color and texture aren’t accurate indicators.
The temperatures worth memorizing:
- Poultry (chicken, turkey, ground poultry): 165°F (74°C), no exceptions
- Ground beef, pork, or lamb: 160°F (71°C)
- Steaks, roasts, and chops (beef, pork, lamb): 145°F (63°C), then let rest for 3 minutes before cutting
- Fish: 145°F (63°C), or until the flesh is opaque and flakes easily
- Egg dishes: 160°F (71°C)
- Leftovers and casseroles: 165°F (74°C) when reheating
Prevent Cross-Contamination in the Kitchen
Raw meat, poultry, and seafood carry bacteria that can spread to anything they touch. Use separate cutting boards for raw animal products and for produce or bread. This single habit eliminates one of the most common ways kitchen infections happen.
After each use, wash cutting boards with hot, soapy water, rinse them, and let them air dry. For a deeper clean, sanitize with a solution of 1 tablespoon of unscented liquid bleach per gallon of water, letting it sit on the surface for several minutes. Once a board develops deep grooves that are hard to clean, replace it. Those grooves harbor bacteria that regular washing can’t reach. The same logic applies to knives and utensils: don’t use the same knife to slice raw chicken and then chop salad without washing it thoroughly in between.
Keep Your Water Safe
In most of the United States and other developed countries, tap water is treated and safe to drink. But if you’re on well water, traveling internationally, or dealing with a boil-water advisory, the treatment method you choose matters because different methods work better against different types of germs.
Boiling is one of the oldest and most reliable options. Bringing water to a rolling boil for one minute (three minutes above 6,500 feet elevation) effectively kills bacteria and viruses. It’s less studied against certain parasites, but it remains the most accessible treatment when you don’t have other tools.
Chlorine, whether from household bleach or purification tablets, is excellent against bacteria and viruses but notably weaker against parasites like Cryptosporidium. If parasites are a concern, filtration is a better choice. Carbon block filters perform well across the board, removing more than 99.99 percent of bacteria, viruses, and parasites in lab testing. Ceramic filters handle bacteria and parasites effectively but let more viruses through. For the broadest protection when traveling, combining a filter with chemical treatment covers the widest range of threats.
Staying Healthy While Traveling
Traveler’s diarrhea affects up to 40 to 60 percent of people visiting high-risk regions in Latin America, Africa, the Middle East, and Asia. The cause is usually bacteria picked up from local food or water your gut hasn’t encountered before.
The classic advice still holds: stick to bottled or treated water, skip ice in drinks, eat food that’s been cooked and served hot, and peel your own fruit. Avoid street food that’s been sitting at room temperature, and be cautious with salads and raw vegetables washed in local water.
Over-the-counter bismuth subsalicylate (the active ingredient in Pepto-Bismol) can cut the risk of traveler’s diarrhea by roughly 50 percent when taken preventively. The downside is the number of tablets required and the inconvenient dosing schedule, which is why most travelers use it as a treatment once symptoms start rather than as daily prevention. Carrying it in your travel kit is still worthwhile for quick relief if you do get sick.
Probiotics for Prevention
Probiotics can shorten a bout of infectious diarrhea by about a day on average, and certain strains show stronger effects than others. The yeast strain Saccharomyces boulardii reduced diarrhea duration by just over one day in trials involving nearly 1,000 children. Lactobacillus GG (commonly labeled as LGG on supplements) performed similarly and was especially effective against rotavirus, cutting symptom duration by about two days in that specific infection.
The evidence is stronger for treating diarrhea once it starts than for preventing it outright, but regular probiotic use does appear to offer some protective benefit, particularly for children in daycare settings and for people taking antibiotics. Doses above 10 billion colony-forming units per day tend to be more effective than lower doses. No serious side effects have been reported in otherwise healthy people.
Rotavirus Vaccination for Infants
Rotavirus used to be the leading cause of severe diarrhea in young children worldwide. Vaccination has changed that dramatically. Two vaccines are available: one given as a three-dose series at 2, 4, and 6 months of age, and another given as two doses at 2 and 4 months. In clinical trials, these vaccines provided 85 to 98 percent protection against severe rotavirus illness, including the dangerous combination of fever, vomiting, diarrhea, and dehydration that frequently led to hospitalization before routine vaccination began.
If you have an infant, rotavirus vaccination is part of the standard immunization schedule and one of the most effective single steps you can take to prevent serious diarrheal illness in the first few years of life.
Disinfecting Surfaces After Illness
When someone in your household has diarrhea, especially from a highly contagious virus like norovirus, cleaning surfaces with regular soap or all-purpose spray isn’t enough. Norovirus particles are tough and can survive on countertops, doorknobs, and bathroom fixtures for days.
The CDC recommends disinfecting contaminated surfaces with a bleach solution of 5 to 25 tablespoons of standard household bleach (5 to 8 percent concentration) per gallon of water. Leave the solution on the surface for at least five minutes before wiping it away. You can also use an EPA-registered disinfectant specifically labeled as effective against norovirus. Pay special attention to toilets, faucet handles, light switches, and any surface the sick person has touched. Wash contaminated laundry on the hottest appropriate setting and dry thoroughly.