I don't think we need to really wait much longer to see the impact of this policy. It was decriminalized in 2001, so 16 years has passed, and there has not been an increase in drug use during this time, obviously less people thrown in prison, and diseases like HIV have also decreased significantly.
I'm not saying Portugal has done the perfect job, because it's only decriminalization. Full legalization would yield even more benefits, because it will involve regulation and quality control of the actual product. As long as you force people to get their drugs illegally, the real risk to their health is that the substance is not pure, and is either something different than what they're saying, or has been cut with other substances. But all in all, decriminalization is a step forward in civil liberty, which is the opposite direction of the Philippines. They are taking a step backwards.
You need to remember that Portugal is a rich developed nation, and the Philippines is a poor developing country. If you legalize the drugs in the Philippines, it may not yield the same results as they had in Portugal. On the other hand, I am afraid that it may increase the addiction rates among the teenagers.
Rich? Portugal was on the verge of financial collapse a few years ago. I agree that it is far more developed than the Philippines, but I'm not sure if that is a game changing difference. The success in Portugal isn't because of wealth.
Let's talk about teenagers getting their hands on drugs. First, if you're concerned about addiction, we can only talk about addictive substances. But I agree in that we don't want kids having access to drugs. Kids will have the hardest time acquiring a drug that is legal. Think about tobacco or alcohol. It is government regulated, distribution is regulated, and you need to show that you are an adult with ID in order to purchase either of them. Now take a drug that has been made illegal. It's not regulated and you need to get it from a drug dealer. But a drug dealer may or may not care about selling drugs to a kid, due to the profit motive. It is much easier for a kid to get his hands on weed than it is cigarettes.
So if that is your actual fear, you should be for the legalization and regulation of drugs, because the government can institute a system to distribute only to adults.