does alcohol show up in hair follicles

No.

I did a web search and while some tests do not, if they are looking for it, it will. Most tests are for illegal drugs when they do it, and the additional testing is not done.

WOW.... It seems as if the hair tells all.. no wonder so many police shave there heads.
I am kidding of course.

while this is sorta off thread, actually most police shave thier heads or cut very short, if someone grabs your hair, and pulls they can control you.
For most when they are in academy one of the instructors will do this to help show you not to leave your hair long.

My husband was a very heavy pot user and has quit, but it has only been a little over a week. He has been offered a new job and has to do a hair follicle drug screen. Is there anything that really works? I see the shampoos and things, but I don't know if it is really worth trying. Does anyone have any ideas or real evidence that these products work?

no, only time effects hair folicle.