The main health issues in Viet Nam come from either insect bites or poor hygiene. In both cases, the best way to save yourself from any annoyances is to prevent danger: mosquitoes repellents first, and second, an irreproachable hygiene!
In Viet Nam we have local health centers and doctors – nurses, but their number still remain insufficient to cover the entire population, especially in rural areas. In case of problem, you have to ask directly to the pharmacist and do not hesitate to come back to the city. Health centers are only Vietnamese speaking. However, we do have French hospitals in Ha Noi and Ho Chi Minh City.
Finally, about medicine, we can find them easily, both in the city and the countryside. Some of them carry the same commercial name than the one in France (Immodium, Doliprane…). However, most of the time, you will have to specify the name of the active principle (Paracetamol…)