I am not sure how old this movie is as my only memory of it was from a younger version of myself (maybe 4 or so)

the movie i am looking for is that it is set in a medieval time period. A man has been drugged or put under some hallucinate, whilst under this drug everyone he sees are now monsters. Believing that everyone is a monster he kills the princess of the kingdom and does not realise what he has done. i think from then he is then taken to court, or to the king (something along those lines) here he is waiting for a punishment for accidentally killing the princess.

would be appreciated very much if someone could help me out

Thank you!