What substances cause a false positive for THC?

Answer by  Abaddon (82)

The most notorious substance for causing a false positive is poppy seeds. These are commonly found on poppy seed bagels and in poppyseed muffins. However, you would need to eat a great deal of poppy seed in order to test positive for THC.

Answer by  jsmith (2067)

Some of the more common ones that have been shown to have the possibility include: Dronabinol; Ibuprofens such as Advil, Motrin or Excedrin; Naproxen such as Aleve; and Riboflavin supplements.