How safe are painkillers for long term pain management?

[Jeanne]

My partner suffers from knee joint pain but refuses to take any painkillers as he says that masking the pain then carrying on as if there was no pain is dangerous. He just lets the pain limit his activities and reckons its his body telling him now far he can go. I asked my boss who is a pharmacist and he said he didnt know how to answer that.

Also a lot of people take anti inflammatories everyday semi long term just so they can continue working or doing their every day activities, which also seems wrong as what if they are doing more damage to themselves?

What are your opinions?

PS: im not after suggestions about my partners knee he is happy with his herbal remedies lol just wanna know your opinions about usage of painkillers
I dont mean for chronic diseases or for broken bones or anything like that I am meaning for just niggling pains that have no previous medical significance.