Drew Barrymore failed to attend her first audition. Director Katt Shea wanted Drew for the part of Ivy, and arranged another audition which Drew Barrymore also failed to attend. After Shea spoke with Drew's agent and told her she was no longer interested in her for the lead, she pleaded with the director to give Drew another chance. Drew ended up auditioning at Shea's home, not knowing that the director had already decided she had the job.
Leonardo DiCaprio had a very brief cameo in the film as a student, credited as "Guy". This was his first role in a theatrically released film (his previous film, Critters 3, was direct to video) and his only non-speaking role.
Based on an experience that producer Melissa Goddard had when she was younger. She had a friend stay with her and her family and eventually the friend seduced Goddard's stepfather, Mike Medavoy.
This movie helped spawn a genre of "lethal lolita" or "slutsploitation" films around that time where a young woman uses her sexuality as a weapon to destroy a family.
Katt Shea came up with the title, 'Poison Ivy' after shooting began and instantly doubted it and thought it was silly. Only after the crew agreed with her and told her to 'go with her heart' did she stick with the title.