Since the 1960s there has been a trend for readers to identify an underlying drug theme in the book and in the film adoaptations. this theory stems from the an odd assortment of characters that she encounters, including the Cheshire Cat, Mad Hatter, March Hare, Tweedledee & Tweedledum.
The Cheshire Cat disappears leaving only the enigmatic grin behind. Alice drinks potions and eats pieces of mushroom to change her physical state which could also being chaning her perception of real life. The caterpillar smokes an elaborate water pipe which resemble hookah. Everything just seems like it is in a dream like state from the colors that look very trippy to the characters and the strange things that they are doing such ass the Mad Hatter and the gang at the tea party. I do think that the film an the book could be in a way hinting on psychedelic drugs