Obviously, the greatest harms come from the connection with criminality, disease through unsafe needles, or social and other problems. The use of drugs is extremely complex, as are addictions, whether it's to alcohol, nicotine, heroin, or other drugs. They often have similar effects, similar problems. Some people manage them better than others. Designating the implications would make for a long discussion. It's often very individual.
On May 29th, 2008. See this statement in context.