And others in the past she used she didn't think were helpful. For example I guess several years ago she had eczema on her eyelids. Derm prescribed a steroid cream. It didn't work. My wife eventually figured out it was the nickel in her eye shadow causing the problem.
Personally, I think she should be more open to trying some more.
I think she may also have a fear that they could negatively effect pregnancy(she isn't currently pregnant but we would like that to change). Though as far as I have been able to find there isn't a known link.