The effects of speed drugs (amphetamines and methamphetamines) are very obvious to everyone, except the drug addict. Those not addicted see the physical and glimpse the psychological consequences of using and abusing speed drugs. They see that their friend is literally killing himself, but are not sure what to do about it. The one thing friends and loved ones should not do, is ignore it. It is often the concern and intervention of loved ones that ends the addictions by encouraging rehab.