If you need to continuously take a NSAID (like ibuprofen or naproxen) to relieve pain, ask your doctor to consider prescribing a proton pump inhibitor (like esomeprazole) along with the NSAID to protect you against gastro-intestinal (GI) ulcers.
If you notice your stools becoming black, speak to your doctor immediately as this may indicate a GI bleed.
For more info on managing this condition, visit the Arthritis Centre.