The two tabs of LSD that 'Francoise Pascal' takes in the orgy sequence were really two aspirins.
Although completed in 1969, Bloodsuckers did not get a general cinema release until 1971. Filming took place April-May 1969 (copyright 1969).
Director Robert Hartford-Davis refused to have anything to do with the film, stating that he did not believe it to be finished. The film was credited to Michael Burrowes.
On several different-titled versions of the film ("Incense For The Damned", "The Pleasure Seekers" and perhaps others), there is no director credit. On others, direction is credited to Michael Burrowes, a pseudonym for Hartford-Davis.
Françoise Pascal's first role in a horror film, though it ended up uncredited. She joked in an interview years later that she was brought in to be naked in the orgy scene to add excitement because producers felt it was a pretty dull film.