If the answer above is None it means there is no specific mention in the legislation, but you still need to ask local law enforcement before drinking in Philippines.
Minors (defined as under 18 years old) are prohibited to purchase alcohol and adults are prohibited to purchase or provide alcohol to minors. Minors are not prohibited to consume alcohol. Act Regulating the Access of Minors to Alcohol Section 4
You can find more legal details and links here:
Wikipedia Legal Drinking Page