I had a really bad sinus infection once and the pain was intollerable. Zicam was the only thing that gave me relief. I used it for about a week. With antibiotics I was cured and never used the stuff again, and I can still smell the good and bad all around just fine. I’d hate to see a good product get a bad rap because of that operative word “may” cause something.
I've had the same experience. I stopped using Zicam a couple of years ago when I realized that my sense of smell had become impaired. Fortunately I haven't lost it completely. I can't prove the connection, but when I realized that I was missing out on smells I previously would have experienced, I gave up using Zicam. It just wasn't worth the risk.