Fair point. It's not really analogous to "dropping acid" as I put it, but we do have clear evidence of its use specifically for its hallucinogenic properties:

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4224707/

> In the Norwegian tradition, women put an ointment contain mixture of some plants such as BH on parts of the body with thin skin and became hallucinated

> It Soothsayers applied BH as a component of their hallucinatory mixture