This is one of those questions I've never had a consistent answer to.. even from CML specialists and haematologists!
Some say avoid paracetemol because it is, like Glivec, metabolised in the liver. The implication is that the two together might put a strain on it. That's common advice in the US I know. Certainly long term use of paracetemol is not a good idea generally as it isn't good for the liver but short term is I think OK. I've certainly taken it.
Others say avoid ibuprofen because, while it is my understanding that it is not metabolised in the liver, it is, like Glivec, a stomach irritant. Long term use of ibuprofen is also bad for the kidneys (completely unrelated to Glivec). Again, I've taken this short term too.
A third group say either is OK when you have a cold or need pain relief (and for that they work quite differently - ibuprofen best for muscle pain and headaches as it's an anti inflammatory; paracetemol seems, for me at least, to be best for general malaise and temperature control), but it's a good idea if you do not take the maximum daily dose. Most of the consultants I have seen have said this. I guess there may well be some people who are more susceptible to the liver issue, so should take ibuprofen, and others to the stomach issue, so should take paracetemol. That's something to discuss with your consultant.
One day I am sure we will get advice on what really is the best course! For the moment, I do use painkillers much less often than I did before CML.
Best
Richard