The Philippines has good basic healthcare services, especially in the cities. However these services tend to be expensive, and therefore, medical insurance is essential. It is also advisable to get vaccinations against cholera, hepatitis A, typhoid and dengue fever. A yellow fever certificate is necessary for those travelling from an infected area.
The risk of malaria is high, so carry insect repellents and antibiotics; however, medicines should be carried in their original packaging along with their prescription. Be careful when eating outside and drink only bottled or purified water. 
Travel to the Mindanao region is unadvisable. The region is rife with ethnic and religious tensions. It is also prone to violent fighting between the army and militant outfits like the Abu Sayyaf, who operate out of this region. Criminal/terrorist organizations are known to abduct tourists, so vigilance is essential.