
This book by the publishers of Consumer Reports is the most informative book on drugs and addictions on the market. Originally published in 1972, it documents in great detail not only the impact of drug use, but also the greater harms that arise from our efforts to Prohibit these drugs. It as is if we never learned from the massive increase in crime and and bloodshed from our disastrous thirteen year experience with Alcohol Prohibition. It has several chapters dedicated to each drug from caffeine to heroin and amphetamines. A must read for anyone who wishes to develop pragmatic solutions to America's drug use dilemma. In almost every instance our policies dealing with illicit drug use CAUSE more harms than use of the drugs themselves. This should be required reading for every member of Congress. It is amazing that so much of what we "know about drugs" is wrong.
The vast majority of the harm illegal drugs do to people is due to the drugs being illegal; it has nothing to do with characteristics inherent to the chemistry of the drugs.
(I recommend the book Licit and Illicit Drugs. You can read it here online: http://www.druglibrary.org/schaffer/Library/studies/cu/cumen... )
Do a little research and you'll find that even for heroin and cocaine the harm done to society by their being illegal far exceeds any conceivable harm done by the drugs themselves. When and where cocaine has been legal, people drank tea from the leaves as a mild stimulant similar to caffeine. When heroin was legal people took it in pill form and addiction was safe and affordable - the main long-term documented negative effect of regular heroin use is constipation. Many people have lived a long and healthy and productive life addicted to these drugs in exactly the same way I've lived one nearly continuously addicted to caffeine (in my case, preferably administered in the form of Diet Coke - your tastes may vary).
When alcohol was illegal, whiskey was cheaper than beer and people went blind drinking wood alcohol; when alcohol was legal again the average potency of what was fashionable to drink declined. That same dynamic applies to every other drug - making a drug illegal makes a more potent, more dangerous product available where leaving it legal lets people use it far more safely - an outcome you can only be opposed to if you carry some sort of Victorian anti-fun meme or if you're convinced that everybody in the world is insane, untrustworthy and lacking in judgment except the angels we've found to regulate the rest of us.
I recommend the book Licit and Illicit drugs, which you can read for free here:
http://www.druglibrary.org/schaffer/library/studies/cu/cumen...
You could also just look up any of the drugs you're worried about in an old-fashioned paper encyclopedia.
[1] C.f. The Consumer Union Guide to Licit and Illicit Drugs.
[2] Not counting polydrug deaths.