I agree with what others have said

but would like to add…..Why should it be any of that friend’s business what meds you take? Maybe they are well intentioned, but they do NOT have to experience the pain you are in.
It’s like asking why one goes to a particular church or buys/eats particular foods… Their being ‘anti-medicine’ is their choice. You don’t have that choice right now. Make it an ‘out of bounds’ subject. Respect their own views, but make it clear that you wish for THEM to respect YOUR views as well. End of discussion!
Maybe the concern is that old saying ‘But, you look just fine!’. Not many people can even imagine the pain we can and do experience to different degrees.
I simply put that the pain is like that of having your arms legs etc dipped into hot french fry oil. Severe burning, but, from the inside out. That is something many can relate to in varying degrees, usually.
It can be touchy if they are close friends, but true friends respect or should respect certain personal boundaries.
I have a spare cane I can lend you to thownk some sense into them if you need it. Hope this helps.