If you smoke weed three times, a little over 4 months ago would you pass a hair test?

May be : Hair tests measure rather non-psychoactive residues that remain in the hair for months afterwards. These residues are absorbed internally and do not appear in the hair until 7-10 days after first use. Afterwards, they cannot be washed out by shampoos (though shampoos may help remove external smoke particles that hat get stuck in the hair).