So, in this move a middle aged man is losing his hair & he can’t take it. One night while watching TV he sees an infomercial that statesv that this new hair growth product is guaranteed to make his hair grow basically over night. Bring desperate he ordered a bottle.
When it arrives he instantly uses it. When he go to sleep, he wakes up with a head full of hair. He loves it. But what he doesn’t know is that while he sleep, his hair is removing itself from his head & things one on murder sprees.
I vaguely remember a comical episode of Spielberg’s Amazing Stories in 1986 about a killer toupee. It crawled around and it murdered people. I went through the episode guide at imdb and found it. That episode was named Hell Toupee. Maybe not what you are looking for though since it is about a toupee and not a hair growth product. Your question is driving me nuts because I keep thinking I saw a different horror anthology show from that same period that was about a hair growth product that had some sort of disastrous result. I watched a lot of horror anthologies though in the 1980’s. Some show like Tales from the Dark Side, Tales from the Crypt, The New Twilight Zone, The Hitchhiker. Hope if this isn’t the right answer, someone else will know what it was, because now I am curious to know the answer too.