leflunomide vs sulfasalazine
Side-by-side comparison of leflunomide and sulfasalazine Data from FDA drug databases (Orange Book, NDC Directory, recalls, shortages) covering 20,000+ approved drugs, plus CMS pricing; see our methodology.
Arava
Azulfidine
Leflunomide is a drug that can help reduce the symptoms of rheumatoid arthritis. It works by slowing down the body's immune system.
Sulfasalazine is a drug that reduces inflammation in the body. It is used to treat ulcerative colitis.
Leflunomide treats active rheumatoid arthritis in adults. Rheumatoid arthritis is a disease that causes pain, swelling, and stiffness in the joints. This medicine can help reduce these symptoms.
Sulfasalazine treats ulcerative colitis, a condition that causes inflammation and sores in the lining of the large intestine. It can help with mild to moderate ulcerative colitis. It can also be used with other treatments for severe ulcerative colitis. This medicine can also help keep ulcerative colitis from coming back.
Leflunomide is a pyrimidine synthesis inhibitor. This means it blocks a certain process in your body. By blocking this process, it can reduce inflammation and slow down the damage to your joints.
Sulfasalazine is an anti-inflammatory drug. It works by reducing inflammation in the colon. The exact way it does this is not fully known.
- • Diarrhea
- • Respiratory infection
- • Nausea
- • Headache
- • Rash
- • Loss of appetite
- • Headache
- • Nausea
- • Vomiting
- • Stomach upset
- The medicine is not working 36,982
- Rheumatoid arthritis 24,921
- Pain 20,055
- Joint pain 16,943
- Cannot tolerate the medicine 15,586
- The medicine is not working 29,013
- Rheumatoid arthritis 19,190
- Pain 15,658
- Cannot tolerate the medicine 13,521
- Joint pain 13,161
This drug can cause serious harm to an unborn baby. If you are pregnant or could become pregnant, you should not take this medicine. This drug can also cause serious liver problems. If you have liver problems, you should not take this medicine. Your doctor will monitor your liver with blood tests.
You should not take this medicine if you have a blockage in your intestines or urinary tract. You should not take this medicine if you have porphyria, as it could cause an attack. You should not take this medicine if you are allergic to sulfasalazine, its ingredients, sulfonamides, or salicylates.
Do not take leflunomide if you are pregnant. It can cause birth defects. If you are breastfeeding, you should stop while taking this medicine.
Tell your doctor if you are pregnant or plan to become pregnant. It is not known if Sulfasalazine will harm your unborn baby. Talk to your doctor about the risks and benefits of taking this medicine while breastfeeding.
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How to Read This leflunomide vs sulfasalazine Comparison
leflunomide is classified in the Disease-Modifying Antirheumatic Drug (DMARD) drug class, while sulfasalazine sits within the Disease-Modifying Antirheumatic Drug (DMARD) class. Because both drugs share the same classification, they are often considered interchangeable in theory — but clinical outcomes rarely track that cleanly. Both drugs are prescription-only, so a licensed provider must authorize use.
Adverse event totals above are pulled from the FDA's Adverse Event Reporting System (FAERS). For these top-ranked reactions alone, leflunomide has 114,487 submissions while sulfasalazine has 90,543. Those figures reflect cumulative reporting volume — not per-patient risk — so older, widely dispensed drugs typically look worse on count alone. No direct interaction between these two drugs is listed in our FDA-derived dataset, though co-prescription still warrants pharmacist review. Serious warnings, pregnancy guidance, and contraindications can differ even when indications overlap.
A table cannot substitute for clinical judgment. Effectiveness, tolerability, drug-drug interactions with your other medications, kidney and liver function, pregnancy status, insurance formulary, and price all feed into a decision that only a licensed prescriber can make responsibly. Data here is sourced from FDA Structured Product Labels (SPL) and FAERS, both of which update as manufacturers and clinicians submit new information. This page is for educational purposes only, is not medical advice, and should not be used to self-switch between leflunomide and sulfasalazine — always consult your physician or pharmacist first.
Important: This comparison is for informational purposes only. Drug effects vary between individuals. Always consult your doctor or pharmacist for personalized medical advice.