There are some drugs that do more harm than most. Here's a study published by the Lancet on Nov., 1, 2010 showing what kinds of substances have been doing the most harm so far.

Researchers led by Professor David Nutt, asked drug-harm experts to rank 20 drugs (legal and illegal) on 16 measures of harm to the user and to wider society, such as damage to health, drug dependency, economic costs and crime.

Alcohol came out on top as the most harmful drug in Britain, beating heroin or crack cocaine by a huge margin.