Am I allergic to my Trumpet?
The mouthpiece of most brass instruments is made of (guess what?) - brass. This is often plated with another metal which looks silver, but is less expensive - Nickel.
I heard this originally from my husband, who is not really a brass player, but more of a guitar dude.) My husband says his high school music teacher told his brass players at that time, to coat the mouthpiece with clear finger nail polish if they started to react to it. Apparently the reaction is know among musicians as "Brass Poisoning," but we know it as our old friend, "Nickel Allergy." Reactions to the brass itself are also possible, and relatively common, however.
(Now, I cannot comment on the wisdom us using nail polish for anything near your lips - I can only think that this is not a good idea either. Nail polish is a type of plastic, and has it's own toxin issues.)
After a small amount of reading about the subject of allergies which haunt brass players, there appear to be a couple of possible options for those sensitive to nickel. Stainless Steel and Titanium mouthpieces are available, and would be much safer. A couple of other synthetic materials with which I am not at all familiar, are called Lexan and Delrin. These materials are apparently available as mouthpieces for brass players, and are considered to be hypo-allergenic. Standard mouthpieces can also be coated in sterling silver or different grades of gold, though these can also include very minor amounts of nickel, which can sometimes cause or irritate an allergic reaction.
You can certainly inquire about this of your local band instructor, hopefully before there is a problem. You can also do a little research, or ask at a band instrument shop. Your best defense is your questioning mind.
Nickel Allergies begin when small amounts of nickel enter the bloodstream, or over periods of long exposure. Either of these events could occur for brass players. If you get any little cut or blister on your lips, that could be enough for the nickel to enter your bloodstream. Assuming you are practicing you instrument at all, your exposure will go on for extended periods of time, possibly for years of your life. Don't avoid your instrument. Avoid the nickel.