Honest about the risks, and specific about what prevents each one.
Drowning and riptides
The Government of Canada states that coastal waters can be dangerous, that tidal changes and strong winds can cause dangerous riptides, that lifeguard and rescue services do not always meet Canadian standards, that many beaches have limited or no lifeguards on duty, and that several drownings occur every year.
Prevention Check whether the beach has a flag system and whether anyone is actually watching it. Swim where other people are. Do not let a strong pool swimmer, adult or child, treat the ocean as the same activity — and if you are caught in a rip, swim across it rather than against it.
Malaria
CDC recommends preventive medication for travellers going to certain areas, naming Azua, Elias Piña, La Altagracia, San Juan and Santo Domingo — including resort areas — plus the La Ciénaga and Los Tres Brazos areas of Santo Domingo city. It recommends none for the rest of the country. The Government of Canada says only that there is a risk in certain areas or at certain times of year.
Prevention Bring your resort name and dates to the consultation. Whatever we decide about tablets, the mosquito precautions stay: repellent, covered arms and legs after dark, air conditioning or screens at night.
Dengue
CDC lists dengue as spread by mosquito bite and advises avoiding bug bites. The Government of Canada says dengue is a risk to travellers in this country and that there is no vaccine or medication available in Canada to prevent it.
Prevention A repellent containing 20% or more DEET, as CDC specifies, reapplied through the day. The mosquitoes that carry dengue bite in daylight, so evening-only precautions miss them.
Zika
CDC lists Zika as spread by mosquito bite and notes an infected pregnant woman can spread it to her unborn baby. The Government of Canada says Zika virus is a risk in this country and can cause serious birth defects.
Prevention If you are pregnant or planning a pregnancy, this belongs in the conversation before you book rather than after. Otherwise the same daytime mosquito precautions.
Chikungunya and Oropouche
The Government of Canada names both. Chikungunya joint pain can be severe and last for months or years. For Oropouche it says there is no vaccine and no medication that protects against it. CDC does not list either for this destination.
Prevention Repellent is the whole strategy for Oropouche. It is carried by biting midges rather than mosquitoes, which is why ordinary netting can miss it — fine mesh or air conditioning works better.
Roads and traffic
The Government of Canada says road safety varies considerably across the country, that accidents occur frequently, that drivers do not always respect traffic laws and often speed and can be aggressive and reckless, that drinking and driving is common, and that pedestrians do not have the right of way even at traffic lights. CDC names motor vehicle crashes the number one killer of healthy travellers abroad.
Prevention Use the resort transfer or a booked taxi rather than an informal ride. Assume a green light does not mean a car will stop. Scooters and quad bikes are how most holiday injuries here begin.
Food and water
The Government of Canada gives the plain rule: boil it, cook it, peel it, or leave it. CDC advises avoiding contaminated water and soil.
Prevention Bottled water including for brushing teeth if you are outside a resort, ice you would trust, food served hot. Rehydration salts weigh nothing and we can discuss a standby antibiotic where it is appropriate.
Freshwater, if you leave the resort
CDC advises against swimming in freshwater in developing areas or where sanitation is poor, and names leptospirosis, schistosomiasis and melioidosis among freshwater and soil exposures. The Government of Canada adds that water can look clean and still be contaminated, and advises avoiding getting freshwater in your eyes, mouth or nose.
Prevention This one is for the river tour and waterfall excursion crowd, not the pool. Keep cuts covered, dry off properly, and mention any river swimming to us if you feel unwell afterwards.
Getting treated
The Government of Canada says good health care is only available in major cities and that quality varies greatly across the country, that medical facilities may require payment up front, and that private hospitals and doctors may also require payment in advance.
Prevention Travel insurance that covers medical evacuation, with the policy number saved offline and a copy left with someone at home. Carry a written list of your medications — a Spanish copy is better.
Crime
The Government of Canada advises exercising a high degree of caution in the Dominican Republic due to crime. It notes crime including violent crime occurs across the country and especially in major cities, that petty crime such as pickpocketing and bag-snatching occurs frequently with tourists a common target, and that drive-by robberies by thieves on motorcycles, scooters or bicycles are common.
Prevention Not a pharmacy question, but it affects what you carry. Keep medication and documents in the room safe rather than a beach bag, and take a photograph of everything important.