Is there any way to remove nicotine stains from a fiber glass shower

Nothing can clean the brown stain. There are companies that can resurface fiber glass showers and tubs without removing them. Check your phone book for Tub Refinishing.

This link might give you some ideas that you have not tried. Hope it helps.

https://www.google.com/search?q=how+to+remove+nicotine+stains+from+fiberglass&rlz=1C1BLWB_enUS700US700&source=lnms&tbm=isch&sa=X&ved=0ahUKEwjw08n4tMPXAhUD8mMKHVDdC4IQ_AUIDCgD&biw=1422&bih=629&dpr=1.13

I have the same problem and I'm scared because I live in a rental. The only thing I haven't tried yet is something called trisodium phosphate. Have you tried it yet? Plus, I'm going to see if the plumbing store has any suggestions...

Have you tried 'Bar Keepers Friend'? Its worth a try on a small spot to see if it will work. Its also not expensive. Make sure its the powder kind in the can though.

I have heard that oven cleaner will remove the brown smoke stains off windows which are also very hard to remove.. If you do try this, only try one inconspicuous small spot first as it may remove the finish on the fiber glass.

we had ugly ciggerette burns in the Formica sink counter and edge of the tub in the condo we purchased. After reading other posts concerning this I decided to try the sand paper and it freaking worked!!! It didn't scratch the counter or tub and the stains came out quickly. I used the fine grit sand paper and wet it. Applied a few seconds of light pressure on each burn mark and wiped with a clean towel. Thank you to whoever suggested that!