Lewis Carroll, or rather Charles Dodgson, was extremely straight laced and came from a religious background. It is not likely that he would take drugs and it is pretty clear from his diaries that he didn’t. Alice in Wonderland was a story that was constructed during a boating trip with the three Liddell sisters. I can’t imagine that their parents would allow them to go boating with a drug user.
A boat beneath a sunny sky,
Lingering onward dreamily
In an evening of July –
Children three that nestle near,
Eager eye and willing ear,
Pleased a simple tale to hear –
From: ‘A Boat Beneath a Sunny Sky’
By Lewis Carroll