I have a friend whose wife is (I swear) allergic to everything. It's a huge, consuming part of her life.
On top of that, she has breast cancer and her oncologist had to implant little "markers" to help guide the x-rays (or something).
She said, "OK, but the markers have to be ceramic. I'm allergic to just about everything else."
"Oh, don't worry. These are titanium. You'll be fine."
"I'm allergic to titanium."
"That's ridiculous! No one is allergic titanium!"
"I am. Seriously. Absolute fact. I know this."
"You've been misinformed. You're not allergic to titanium."
She switched doctors. Because: she's allergic titanium.
The next doctor said, "You want ceramic? Sure, we can do ceramic markers. No big deal."