Does marijuana smoke stay in your hair forever?
No, exposure to the smoke of marijuana does not stay in the hair
forever, but duration does depend on the frequency and severity of
exposure and frequency of washing hair.
What does happen though is, if a person smokes marijuana there
are traces of it that reaches the follicles and grows into the
hair. A hair sample can be taken from the person and tested and can
prove that he/she smoked marijuana.