I just joined the group today and I can't believe that no-one seems to have mentioned reactive arthritis yet. I am a 71-year old male who is (was) physically active and relatively fit. Until my T1 Grade 3 bladder tumour (with satellite tumours and carcinoma in situ). I had a TURBT followed by 6 BGT treatments. After #5, my joints started to swell and hurt badly - fingers, wrists, elbows, knees, ankles, toes (the lot). From regular long walks, kayaking, cycling and swimming I was reduced to negotiating stairs like a crab, one step at a time and hanging onto the banisters; walking slowly with two sticks; shaving left-handed; unable to hold a pen; you get the picture.
Anyway, they say that reactive arthritis is a less-common side-effect of BCG, that my auto-immune system has over-reacted and is now attacking my own joints. My GP prescribed the NSAID Naproxen (1k mg daily) which eased the pain a bit; now he wants me to go on the corticosteroid Prednisolone (10mg daily) as well. Tomorrow I am to have my follow-up cystoscopy and I will ask the consultant whether the steroid is likely to undermine my therapy as it apparently suppresses the auto-immune response.
Sorry to rabbit on but I wonder whether anyone else in the group is having (or has had) a similar experience.