Definitely talk with your rheumatologist because mouth ulcers can be a side effect of DMARDs. I'm on methotrexate and a biologic and my rheum proscribes folic acid to stave off side effects of the methotrexate.

HenryK,
Welcome!
Blisters can be a side effect. Whenever I get them, I hold some Lawry's seasoning salt on the blister and it usually goes right away. If it continues, or doesn't clear up you want to let your Rheumatologist know what is going on.

Im on leflunomide and i get blisters inside my mouth a good bit. I think its another side effect

I am on this medicine,i get those ulcers in my mouth also.painful🥺

Since I got RA I believed that if I could find the trigger, I could reverse the effects. I was wrong. It comes and goes as it pleases.