Staying healthy in Cambodia can be a major challenge. It seems that everywhere you go something is conspiring to make your life shorter and more painful. Food, in general, is relatively safe. Avoiding the most obvious threats like uncooked fish that has been lying in the hot sun all day will help.
One of the main threats to the traveler in Cambodia is himself. Many people show up with a notion of invincibility. They have random, unprotected sex, sometimes with prostitutes. They take drugs and drink all the time, rarely sleeping before dawn, and then they get sick or their health collapses. It’s depressingly common, and very easy to get sucked into. The temptation to indulge in behaviors that would be unthinkable in other places is suddenly nearly omnipresent. Frankly, for many travelers, Phnom Penh is the end of the road, at least psychologically.
Traffic is the other big risk. Even walking down the road is an activity full of danger. It is essentially to be constantly vigilant, or you will get run over by a tuk-tuk or some other vehicle. Obviously, climbing on the back of a motorbike with a local isn’t always a safe bet, either. Motodops and tuk-tuk drivers are often drunks.
Doctors will often be a sad joke, as will virtually every other service imaginable. Imagine a society with no government to fix anything or provide any safety net or basic services to its people and you will have a fairly accurate picture of the Cambodian situation.
Violent crime, at least, is relatively rare, though it does happen. There is the occasional shootout at a nightclub or violent robbery, but in general most murders are for revenge. It’s wise for a foreigner to remember that he’s far outside of his realm and that he should show respect for important family values. Women are the easiest way for a foreign man, particularly, to get into trouble.