Medical services in Cambodia are unfortunately still poor - there are only a handful of good hospitals all over the country. It is best if you stay healthy - drink only bottled water, not from the tap, wash your hands often, eat fruit only if it has been thoroughly washed and peeled and meat and fish only if they are thoroughly cooked and served hot, etc. For drink bottled water is recommended, as already recommended, or soft drinks like coca cola in cans or bottles. The fluid of young coconuts is very refreshing (and it is also sterile and thus safe). Vaccinations against tetanus, hepatitis, and typhoid are a good idea.

Malaria is in general a problem in Cambodia but as long as you stay close to the tourist centers in Siem Reap and Phnom Penh you should be safe. Nevertheless, it makes a lot of sense to use plenty of mosquito repellent at and after dusk - even if they do not transmit malaria mosquito bites can be a nuisance.

In particular, bring some medicine against colds - it is astonishing how easily people from colder countries catch a flu in this tropical country. It happens when you enter an air-conditioned car or building, coming in from the hot, humid air outside. Under these conditions a cold develops in no time at all - and finding medicine against cough or running noses in the local pharmacies is surprisingly difficult - the condition is apparently not common in Cambodia.

Safety

Unfortunately, Cambodia is not an entirely safe country to visit, although the situation has improved in recent years. It is not a good idea to walk out alone at night. Take proper taxis, not motorcycle taxis. Do not travel in the countryside after dark, always make sure to be at your destination before the sun sets.

Land mines are no longer a problem in the official Angkor visitor area, but outside of it you must still take care - only walk on established paths and take heed of land mine notices.