Catching addiction early is crucial. Because addiction signs can be subtle, it is often the case that users will end up overdosing before they or their loved ones have even realized they have a problem.
With prolonged usage, the user will develop a tolerance causing them to increase dosages. These increases will not improve the efficacy of the drug, but will guarantee physical dependence on the drug. Once this dependence is established and the drug is not available the withdrawal symptoms discussed earlier will begin with cravings and other uncomfortable conditions. The psychological dependency is quite powerful and makes it almost impossible to stop using, even if someone wants to.