Alcohol, my first drug, caused me a lot of harm in my teenage years, as I drank to excess nearly every time. Often I was vomiting down the toilet, lying immobile on the bathroom floor, vomiting in streets and gardens; I pissed the bed sometimes and held onto a psychological addiction to alcohol relating to a shyness in the presence of prospective females for a couple of years, which I am glad to say I recovered from (and I didn't ever piss in the bed with them).
I was introduced to alcohol from the age of six or seven with cider and I remember well how I loved the smell of whiskey as a small child, which I would occasionally be given to drink with hot water, cloves and sugar before bed. I got properly drunk first at thirteen, and drank regularly as a fourteen, fifteen, sixteen year old.
Now, as a thirty-nine year old, I drink rarely and enjoy five or six units, two or three times a year perhaps. (
http://en.wikipedia.org/wiki/Unit_of_alcohol). I do know the after-effects of alcohol can be harmful but as with any drug experience I would weigh up the pros and cons and decide whether it would be safe to do at the time. Set and setting have a part to play and there would be a clear decision to partake. I would not drink just because it's available, there would usually be a decision in advance of the time. Generally, the less often, the less I want to do so, and the desire to drink comes up so rarely nowadays, and I am happier.
As for the medical evidence, according to Professor David Nutt in the UK, there are generally no health benefits for women's consumption of alcohol, and a very slight benefit for middle-aged men upwards of about one unit or less daily, like a small glass of wine, in terms of lowering blood pressure slightly and reducing the incidence of heart disease and stroke. Anything more and the health-risks outweigh the health-benefits. Of course, there are exceptions who can drink and live long too (eg.
http://en.wikipedia.org/wiki/Jeanne_Calment).
Sadly, I have seen many alcoholics die over the years as well as knowing of victims killed through violence and accidents, from being run over and killed (DUI), to a drunken sword stabbing during an argument, a glassing, general violence and hospitalisations. Close family members have succumbed to alcoholism. Alcohol has been quite a horror story now that I come to think of it.
The opiate addicts I have known who died, there are several, were primarily addicted to alcohol which is more physically addictive than heroin because the withdrawal symptoms of alcohol, for the severe alcoholic, can easily be fatal. The physical ailments they died from were mainly alcohol-related. Many poly-drug users are alcoholics in my experience.
Although I might drink occasionally, I would say alcohol at its worst is truly the basest of drugs, psychologically and physically among the most damaging, but still preferable and having a safer psychological profile to a drug like cocaine, for example. I am not currently motivated to give up alcohol altogether, my freedom to choose is still important to me, but for a longer, healthier, happier life I would certainly recommend practising getting as near towards teetotalism as you can.