On a recent trip to Tanzania with four grandsons, my most important task (beside protecting them from the jaws of a lion or leopard) was to keep them, and myself, in good health. It would not have been much fun to be stuck in a tent next to the commode or flattened on a cot while the rest of the gang viewed a dazzling array of wild animals from the safety of a Land Rover.

Although I came prepared for the worst, I did everything I could to make our trip the best. And I’m happy to report, no one got sick and we all had a great time.

When I described the steps I took to friends and physicians, they urged me to write about them. So here goes, along with a host of other helpful travel hints from well-informed professional sources.

No. 1: I reminded my grandsons daily, any water you drink or use to brush your teeth must come from a sealed bottle that you open. Ice wasn’t an issue in the bush, but that too should be prepared from bottled water. When you take a shower or swim in a pool, keep your mouth shut. (This warning was particularly pertinent for one grandson who always sings in the shower.)

No. 2: Before every meal, we each chewed one pink tablet of bismuth subsalicylate (sold as Pepto-Bismol and various store brands).

I have used this preventive since first reading about it in 1980 in The Journal of the American Medical Association in a study led by Dr. Herbert L. DuPont, an infectious disease and travel medicine specialist at the University of Texas, Houston. The study described how using these tablets greatly reduced the risk of traveler’s diarrhea among American students traveling to Mexico. In a subsequent study published in 1987, Dr. DuPont and colleagues reported that two tablets chewed four times a day reduced the risk of developing diarrhea by 65 percent. (Each tablet contained the standard dose, 262 milligrams of bismuth subsalicylate.)

I have relied on these tablets, albeit in a lesser dose because I’m a lot smaller than average, during trips to Vietnam, Thailand, Peru, Indonesia, India and Nepal, and never got sick despite eating salads and peeled fruit, which one is warned to avoid. In fact, in India and Nepal, my traveling companion, who also took the tablets, and I were the only ones who stayed healthy even though the others in our group assiduously avoided those no-no foods and we did not.

So for the five of us going to Tanzania, I packed 15 tablets for each day of our trip — and no one experienced the slightest gastrointestinal upset. That wasn’t the case, though, for most of the others on our itinerary. However, if you choose to try this preventive, I suggest you check first with your doctor and perhaps consider using Dr. DuPont’s larger dosage.

Without a preventive, which is no guarantee against food-borne illness, stick to “safe food” that is cooked and served hot, and fruits and vegetables you have washed in bottled water and peeled yourself. Never eat undercooked foods — eggs, meat, fish or poultry — or any food sold by street vendors.

Reduce your exposure to germs by washing your hands often, and always before eating. A hand sanitizer with at least 60 percent alcohol can be used if soap and water are unavailable.

I took no chances, especially since I was responsible for four children. I had an emergency supply of Lomotil (for digestive problems) and azithromycin (Zithromax Z-pak, for infections) just in case.

No. 3 (really No. 1 chronologically): I made sure we were all up-to-date on routine vaccines — measles-mumps-rubella, varicella (chickenpox), diphtheria-tetanus-pertussis, polio and an annual flu shot — and added two (for hepatitis A and typhoid) that the Centers for Disease Control and Prevention recommends for travelers to Tanzania. You can review recommendations for other destinations on the C.D.C. website at cdc.gov/travel. We also each filled prescriptions for generic Malarone (atovaquone proguanil) to prevent malaria, and I checked daily to be sure the boys remembered to take it.

I also packed an ample supply of sunscreen, insect repellent with 20 percent or more of DEET, and a first-aid kit of hydrocortisone cream, antibiotic ointment and a variety of bandages, though happily the latter two were never needed. For one grandson prone to motion sickness, I took some meclizine as well.

As the oldest traveler in the group (and the shortest now that my youngest grandson, at age 11, has passed me), I am acutely aware of the risk of blood clots when flying long distances. I always book an aisle seat so I can get up every hour or so and walk around for a minute. It also helps to move your legs and flex your ankles frequently. You might also wear graduated compression stockings on very long trips. Similar precautions apply to long car or train trips.

Although the risk of clots is generally very small, they can be life-threatening. At greatest risk are people over 40, those who are obese or pregnant or have limited mobility (for example, because of a leg cast) or who have a personal or family history of clots. Estrogen-containing medications also raise the risk; I usually take one of those, raloxifene, prescribed to protect my bones. But it can increase the risk of a clot, so I stop taking three days before a plane trip of four or more hours. For more information, check the C.D.C. advisory on blood clots and travel, and talk to your doctor.

Even when traveling alone, I always purchase travel health and medical evacuation insurance because, well, you never know. People on my various trips have broken bones or become seriously ill and had to return home mid-trip. Two men died while snorkeling on separate trips of mine.

Consider carrying a card that lists your blood type, any chronic illnesses or serious allergies and the generic names of prescription medicines you take. Bring some extra doses in case of travel delays.

Other worthy precautions: To avoid nasty parasitic diseases like schistosomiasis, do not swim or wade in fresh water in developing countries or wherever the sanitation is poor. Pools should be chlorinated. However adorable an animal (domestic or wild) may be, keep your distance. Do not touch or feed any animal you don’t know. Some carry rabies. Should you get bitten or scratched by an animal, wash the wound immediately with soap and clean water and, if at all possible, get to a doctor quickly.

If you expect to be at a high altitude (8,000 feet or higher), consult your doctor about medicine to prevent altitude sickness, which can take more than the starch out of a person. I was glad I did when traveling to Cusco, Peru (11,154 feet) and climbing in the Sacred Valley of the Incas (9,000 feet). The recommended preventive is acetazolamide (generic version of Diamox).