Could hydrocodone or other synthetic opioids show up on a hair follicle drug test?

Yes. Hair follicle drug testing is very reliable in identifying chronic or past drug use, and hydrocodone and other synthetic opioids are commonly tested for. Drug testing with hair 4-6 times more likely to identify drug abusers than urine drug testing. Hair tests do not detect recent drug use but do detect use that which occurred 10 - 90 days prior to the test.