A cat in our clinic had to be put to sleep today as it had been poisoned with clove oil. It had bad teeth and the owners thought it would help.
To be fair I had no idea it was poisonous to cats, but I know enough to never assume that just because something is safe for humans that it will also be safe for cats. I've also known people to give their cats paracetamol when they got cat flu (thankfully I found out about that through a fluke within about 40 minutes and so the cats were saved).
So anyway - if anyone should be tempted to try home remedies - be warned.