There were of course other intoxicants appart from alcohol, and some of them were even used regularly. I can only tell you about Spain, where I am from, and because I have read a bit on the matter (I was working on a paper about drug consumption in Prehistory and many references were about drugs in other historical periods). Here, we know people used some plants which have psychotropic effects, like mandrake and black henbane, but sometimes their use was considered witchcraft- which could mean both something dangerous, if you were discovered, but also something taboo but beneficial, if in need; witches were not necessarily considered evil, as they could help solve people's problems. Appart from that, we also know that there was cannabis consumption: there is some debate about its origin and use- they say the muslims introduced it in Spain, and that their military used it before battles to ease their fear, but that may not be its only source, as a pipe was found in Northern Aragón, in a Castle near the Pyrenées, in a moment when we know the place was under Christian regime; and, anyway, Cannabis sativa has been cultivated all along the Iberian Peninsula since Prehistoric times, and, although it was mostly or even only used for its cellulose's properties (to make fabric),we can't discard its use as an incense, just like its documented between some slavic populations during the Roman period.
Particularly in Spain there was also another plant, still used today, due to its opiates: the "adormidera", opium poppy or Papaver somniferum. During famines or whenever somebody didn't have enough food to eat, they ate adormidera, because it had some kind of saciant and somniferous effect and kept the hunger away for a while- many times resulting, anyway, in the death of those consuming it.
The point, anyway, is that they knew for long the uses and properties of many plants, of which a big amount were just growing everywhere, near the roads or between the crops- even some crops like hemp (Cannabis sativa) were known to have intoxicant properties.
About the opinion society had on these drugs, it mostly depends on who you asked and the situation they were going through: while most of the time their use could be considered inappropiate, there were some situations in which it was considered the lesser evil, or even a legit remedy.
I can not give you much bibliography because I'm not that interested in the Middle Ages, but there is one book which, at least here, is a reference to be taken seriously: "A brief history of drugs: from the stone age to the stoned age", by Antonio Escohotado. Also, if you are interested in the use of drugs during Prehistory, there is a more dense book, Elisa Guerra Doce's PhD, "las drogas en la Prehistoria", which, sadly, has not been translated. If you can read fluently in Spanish and have some knowledge about specific terminology on Archaeology and Prehistory, it may be worth the time, because it is absolutely rigurous and tracks its consumption all over the continent at least (I'm not 100% sure if it has some mention about pre-hispanic America, for example).
Hope this helps