How to prevent "Delhi Belly" from eating/drinking locally?

Plastic water bottles can be refilled and recapped. Buy small bottles with distant expiration dates at large formal stores.

I have found that Pizza and Pastries in Mexico are safer. I guess this is because they do not contain much water and would store well even if not fresh. This may apply to fried foods too.

There are lots of excellent answers here addressing food and water safety, which is all very important. But prophylaxis can also help prevent serious illness, and prompt treatment if you feel unwell can vastly reduce the symptoms and duration of the illness and help stabilize things if you need to continue traveling. The US Centers for Disease Control’s Yellow Book (Health Information for International Travel)—the bible of travel medicine—has a chapter on Travelers’ Diarrhea that’s well worth reading in full, including this section:

Nonantimicrobial Drugs for Prophylaxis

The primary agent studied for prevention of TD, other than
antimicrobial drugs, is bismuth subsalicylate (BSS), which is the
active ingredient in adult formulations of Pepto-Bismol and
Kaopectate. Studies from Mexico have shown that this agent (taken
daily as either 2 oz. of liquid or 2 chewable tablets 4 times per day)
reduces the incidence of TD by approximately 50%. BSS commonly causes
blackening of the tongue and stool and may cause nausea, constipation,
and rarely tinnitus.

Travelers with aspirin allergy, renal insufficiency, and gout, and
those taking anticoagulants, probenecid, or methotrexate should not
take BSS. In travelers taking aspirin or salicylates for other
reasons, the use of BSS may result in salicylate toxicity. BSS is not
generally recommended for children aged <12 years; however, some
clinicians use it off-label with caution to avoid administering BSS to
children aged ≤18 years with viral infections, such as varicella or
influenza, because of the risk for Reye syndrome. BSS is not
recommended for children aged <3 years or pregnant women. Studies have
not established the safety of BSS use for periods >3 weeks. Because of
the number of tablets required and the inconvenient dosing, BSS is not
commonly used as prophylaxis for TD.

The use of probiotics, such as Lactobacillus GG and Saccharomyces
boulardii, has been studied in the prevention of TD in small numbers
of people. Results are inconclusive, partially because standardized
preparations of these bacteria are not reliably available. Studies are
ongoing with prebiotics to prevent TD, but data are insufficient to
recommend their use. There have been anecdotal reports of beneficial
outcomes after using bovine colostrum as a daily prophylaxis agent for
TD. However, commercially sold preparations of bovine colostrum are
marketed as dietary supplements that are not Food and Drug
Administration (FDA) approved for medical indications. Because no data
from rigorous clinical trials demonstrate efficacy, there is
insufficient information to recommend the use of bovine colostrum to
prevent TD.

The chapter goes on to discuss prophylactic antibiotics ("at this time, prophylactic antibiotics should not be recommended for most travelers"), and most importantly: treatment options if you do get sick ("The risks associated with the use of prophylactic antibiotics should be weighed against the benefit of using prompt, early self-treatment with antibiotics when moderate to severe TD occurs, shortening the duration of illness to 6–24 hours in most cases"), including oral rehydration therapy, antimotility agents, and antibiotics.

This answer is, of course, not medical advice, but the CDC’s recommendations are a great start for a conversation with your doctor, who can assess the risks and benefits of different medical approaches and their suitability to your medical history, or better yet, you can talk to a specialist at a travel health clinic if one is available to you. In other words, after discussing it with a doctor, you may want to consider a layered defense:

• Intake: Careful selection of food and drinks, avoiding ice and anything else related to tap water, handwashing before eating, etc…
• Prophylaxis: Consider prophylactic Pepto-Bismol/Bismuth subsalicylate if indicated by your doctor and not incompatible with other medical conditions you may have or other drugs you may be taken. 8 tablets/day is a lot to carry and take, but it may be worth it if you’re going to a high risk area, getting sick would really derail your travel plans, or you know you’re particularly prone to TD while traveling.
• Treatment: Carry a range of medications to deal with the problem if you do get sick. Over-the-counter antidiarrheal medications can start working quickly, and your doctor may consider it appropriate to prescribe antibiotics to bring with you in case you need them (if this is the case, you should naturally follow all the instructions and take the entire course of antibiotics as directed if you’ve been given more than one dose). Being prepared can significantly reduce the amount of time you’re sick and limit the disruption to your trip, and it’s far easier than trying to track down the medicine you need in a foreign country while you’re feeling horrible.

Here is advice specific to China (not Taiwan, not other parts of Asia):

As mentioned in Patricia’s answer, avoid the street food. The workers come from rural areas, where the idea of germs or diseases being spread through human contact is unknown. Even in Shenzhen (a tier 1 city), there are still people touching meat with their bare hands to inspect the quality of the meat, without washing their hands before and after. These workers then prepare the food without gloves, and you know what happens next.

The quality of produce in the wet markets / supermarkets is also suspect, due to the widespread soil and water contamination, and the heavy use of pesticides to boost yields. The food provided on the tour buses or restaurants is sourced from safer suppliers, so it is more likely to be safe.

Bottled water handed to you on the tour bus / restaurants is safe. The major brands are 农夫山泉 or 怡宝 – C’estbon, whereas other brands may have quality issues. Bottled water sold on the street is often filled with tap water and then packaged to look like bottled water, so avoid buying from these sources.

China’s Food Safety Issues Worse Than You Thought

I have accepted that I can’t really avoid it without going to great lengths, and plan for it, with an acclimatization period of a few days in every new area.

On my first trip to India, I basically stayed on bottled water and prepackaged sealed food until I arrived at the first place, and then switched to local food and tap water. Given that this was in Himachal Pradesh, that was probably a gentle introduction.

It took about two days to get back to normal digestion, and a repeat of that when I went to Delhi, but from that point on I had no trouble, even when refilling my water bottle from the tap at the train station, and on the second trip, I felt comfortable eating street food before taking overnight trains.

My first visit to the US went similarly, except they don’t have a good train network there.

Bring a few packs of electrolyte solution, and you should be fine.

Lived in various countries in SE Asia for 5 years. You just accept that sometimes you get sick. However, sure you can do things to lower the chances. A lot of good advice has been given. Like someone else here I also don’t agree that ‘good’ restaurants always help. In those places they’re often far less likely to throw expired food out, especially with foreign food, because the ingredients are highly expensive for them. That’s not to say you should go to a place where the flies can be seen laying eggs in the food, but there are some middle grounds here. I have rarely gotten as sick as when I was on an expensive tourist trip with visiting family and we exclusively ate in a resort. 3 out of 5 people got terribly sick there. It’s anecdotal, I know, but I have heard the same from other people too over the years.

One aspect where I radically disagree with most of the "common-sense advice" usually given in this regard is the part about avoiding street stalls and street food. In some parts of the world (specifically, for what pertains my experience, S-E Asia) it could be argued that getting food from a street vendor is even safer than getting it in a "proper" restaurant. Food tends to be fresher (with refrigerators and machines you can make bad food appears still edible) and most important, you can judge its freshness, given how everything is under your eyes. In a restaurant, on the other hand, you have absolutely no certainty that hygienic rules are followed, moreover you get absolutely no possibility of checking if they are washing their pots with sewer water or not. To clarify: there are definitely street vendors that do that, but at least you can see them doing it.

If we want to expand the question, there is an issue at hand. Can you reduce significantly the probability of getting food-related issues? Definitely yes. Should you? It depends.
You can be extremely attentive, eat only western food, sanitise constantly, avoid any food and beverages that is not prepared in front of your eyes, and hundreds of other tricks. Point is, is it worthy? Is it worthy to travel to another country, and avoid the excitement of discovering a new food, because you are only eating western food to avoid diarrhea? The answer is that there is a trade-off between security and enjoyment of travel, and everyone has to decide a certain limit under and over which is not willing to go.

Assuming you’re already infected and have the signs of a stomach disease, you may attempt to reduce the intensity of the symptoms. One recommendation I’ve heard from a couple of people is to take psyllium (Metamucil) supplements. Psyllium is basically soluble fiber and helps both with constipation and with diarrhea. It should also reduce other symptoms, such as excessive gas formation.

However it doesn’t treat the underlying cause and shouldn’t be considered a replacement for proper medicine, if it’s needed for the particular disease one might be having. But it’s nevertheless a good thing to have in your first-aid kit when traveling.

I’ve been in a lot of places, ate everything in every condition, in Indonesia even forgot about not drinking tap water, never ever done something listed in these answers, and never ever ever had a single problem.

The only way to avoid Delhi Belly: improve yourself. Seriously, we as human being have a great potential for adaptation, we have huge resistances and can easily override most basic viruses like those that cause the problem listed above. But…we destroy all of this by never using our body; it’s like a training, so to say.

So, I’m not suggesting to go eat poison or drink spoiled water, but at least let your body use its potential. Seriously, from some of the other answers: “never eat street food”. Well, no. Eat only street food. You’ll have your hell belly ONCE, your body will strengthen, and the next travel in a totally different country you’ll eat stones without problems.

Human body has been engineered to highest level to allow us to do lot of things, but all answers above just put people in a cage that will shrink day after day, to the point that even eating spicy cooked at their home will hurt their stomach. Let your body do its magic, for god sake.

Always wash your hands after handling money. Of course if you don’t trust the water this is best done using some kind of hand sanitizer.

Why You Shouldn’t Put Your Money Where Your Mouth Is (Wall Street Journal article)

I’ve been to China, Egypt, and Peru without any digestive upset. This advice is specialized for the type of travel I go on, tours organized by a competent tour company, and won’t work for other situations:

Eat and drink only what is offered at the hotels, on the bus, on the boat, or at restaurants recommended by the tour director. This meant no street food in China 🙁

Drink only the water that is handed out on the bus, placed in the hotel rooms and cabins, or on the tables at meals. Don’t drink even apparently bottled water not from those sources.

Use hand sanitizer after each restroom visit and before each meal.

Tooth brushing took some care, using bottled water to moisten my toothbrush etc.

While these steps are certainly inconvenient and inhibiting, there is no easier way to really be sure to avoid the Delhi belly. I personally wouldn’t go to these lengths, but they are the answer to the question.

• Get an ozonizer and take it with you in your luggage. Immerse fruits, vegetables, dishes, and other food-related items in water and ozonize them before consumption.

You can also ozonize the drinking water itself. Ozonization will kill nearly all harmful organisms from the water and from the surfaces of items immersed in the water.
It’s better if you use filtered water for this. If you use tap water for this, ozonize longer, and splash some bottled water over each item before use/consumption.

• Bring a small, portable induction cooker and a pot. Get takeaway food and boil everything yourself for several minutes before consumption.

• Drink only bottled water from good, trusted brands.

• Always wash your hands and make sure they are also free of tap water before touching anything related to food.

The ozonizer and induction cooker are somewhat inhibiting while trying to enjoy a holiday. So I might prefer to take a chance rather than follow them. But if you really need to “avoid the Delhi belly”, then I recommend using them.

To memorize and teach it (your kids etc.):

Wash it, peel it, cook it, or forget it.

You have been warned about ice made from tap water. You will often find yourself in situations where “coke” is understood, “no ice” is not. Learn these 2 words in the language of the country you board.

One of:

1. Peel it

2. Boil it

3. Throw it away

Only drink bottled water that has a seal on the cap (they can refill the bottles). Bring hand sanitizer (with a high alcohol content).

I would add:- sterilize your hands frequently and always before eating. If you distrust the water, use an alcohol gel.

My friend and doctor also told me to take some malt liquor (eg. vodka or whisky) with me and have a shot after a meal. It’s supposed to help you also with digesting as well as prevent some “stomach sensations”.

Specifically related to Egypt (but may be relevant in other countries):

I was told by an Egyptian tour guide that one of the things that causes illness amongst British tourists is the richness of the food especially fats/oils and sugar content as this is much higher then we are used to. So his advice was to avoid all Egyptian food and stick to plain ‘western’ foods if at all possible.

Obviously tap water is to be avoided but having said that a (British) friend of mine worked out in Cairo for several years and claimed that he could drink the water!

Basically, you can’t.

The world is full of gastrointestinal (GI) diseases, even in developed, First World nations. There are some decent steps to trying to minimize your exposure:

1. Properly cooked foods. Everything heated to a proper internal temperature (depends on the dish, check the USDA’s site for guidelines), no sampling the raw chicken dish, etc.
2. For fruits and veg, if you can’t peel it, don’t eat it. A tremendous number of GI outbreaks are due to fruit and veg, rather than meat. This includes things like salads – since you can’t really peel lettuce, avoid it.
3. Check if the local water is safe. When in doubt, assume it isn’t. You can stick to bottled water, though there’s always the distinct chance its being bottled from a contaminated source. Coke/Pepsi etc., and beer are good alternatives. Little known fact, the Coca-Cola company is hugely involved in clean water programs worldwide, because they need it for their product.
4. Ice. Ice is bad. Its probably made using the local tap-water, and there are many beasties that can survive an encounter with an ice machine.

But when it comes down to it, nearly every traveller makes some sort of safe-eating “mistake” fairly frequently, whether they realize it or not. At the end of the day, your best bet is to talk to your travel physician, and see if you can get a prescription for an antibiotic. Using that in combination with something like Imodium will probably keep your trip mostly on track – shutting down the problem long enough for the antibiotics to treat the source. Unless of course its viral – norovirus, rotavirus etc. In that event, best of luck.

And if it does happen? Stay hydrated. You’re losing salts and water, they need to be replaced.

Some elementary precautions:

1. Drink no water or other liquid unless it has been boiled or bottled or canned. Be careful using ice; it may have been made from tap water.

2. Avoid eating at roadside food stands; sanitation levels are low. Avoid eating any place where there is evidence of poor sanitation, e.g. flies. Stick with the better restaurants, or with “home cooked” food.

3. Don’t eat anything that hasn’t been cooked or peeled immediately prior to eating. That includes bread, unless it is fresh bread, or just unwrapped.

4. Be careful with utensils. Wash them in boiled, or at least very hot water.

5. Carry pills for dysentery and similar ailments.