In high school, I was taught that one of the main reasons for the crippling of Chinese society and productivity was that opium use was so widespread that it turned a large portion of the country into useless adicts. But other countries, including the USA and Britain had legal opium trades that were never mentioned along those lines. Was opium abuse actually a significant factor in China's weakened state before and after the opium wars?
In the book by Jonathan D. Spence, The Search for Modern China; it wasn't the large number of opium addicts and dens that arose but also the massive trade imbalance that resulted. Millions millions of taels of silver were used to pay for the countless chests of opium, which was a frightening outflow.
P.s. I apologize for such a short answer. I must get going to work and if I spent as much time as I wanted on this I think I'd be in big trouble.