According to the many doctors I've seen, the pills work twice as well when used as a pain-preventer rather than a pain-killer. It's a whole lot easier to prevent pain than to treat it. That's because most pain meds work by blocking pain receptors in the brain. If you block them sooner, there are less of them to accept the pain signal. If you wait until most of them are already agitated, it makes it much harder for the pain meds to work.