Is there anything I can put on the back of the watch to help protect an allergy?

KB985 wrote:

Is there something I can put on the back of my smart watch to prevent an allergic reaction?

No, but refer to How to clean your Apple Watch for some tips on keeping your watch clean. FWIW, I don't have any known allergies, but occasionally my wrist displays some itching, and irritation symptoms. Following the recommendations of that Support Article clears up the symptoms for me.

"Using a 70 percent isopropyl alcohol wipe, 75 percent ethyl alcohol wipe, or Clorox Disinfecting Wipes, you may gently wipe the exterior surfaces of your Apple Watch and your Solo Loop, Sport Band, Nike Sport Band, Ocean Band, or metal band. Don't use on fabric or leather bands. Don't use products containing bleach or hydrogen peroxide. Avoid getting moisture in any openings, and don’t submerge your Apple Watch in any cleaning agents."

Just saw this recent post from claire.thomson Apple Watch Nickel allergy, which may be of interest to you. The irritation which I experience usually occurs from the band, and the Clorox wipes work for me.

You are welcome...hoping your experience improves.