Long term use of aspirin in rheumatoid ahritis is limited by its propensity to cause:
Metabolic acidosis
Hypersensitivity reactions
Gastric mucosal damage
Salicylism
All non-selective COX inhibitors including aspirin on long-term used can cause gastric toxicity ranging from gastritis to peptic ulcer. Selective COX-2 inhibitors have lesser propensity to cause this adverse effect. Salicylism and metabolic acidosis are seen in overdose, not with long term use.
NSAIDs, Gout and Rheumatoid Ahritis