Although this is about one particular pain cream, I suspect that many others may also be harmful or toxic. I do use a pain cream for arthritis, on my hands and feet, so I'm going to take extra pre-cautions to use socks, and wash my hands after the cream has been absorbed. Cats can lick it off the skin directly, or get it on their fur by touching the area where you've used it.

It has been discovered that Flurbiprofen, a non-steroidal anti-inflammatory
drug in the form of pills and creams, but usually in pills, is highly toxic to
the domestic cat. The FDA has issued a warning about it. This short posts is
to spread the word.

You may view the latest post at
https://pictures-of-cats.org/flurbiprofen-pain-creams-are-very-dangerous-to-cats.html