Two medicines, side by side
Sulfasalazine vs leflunomide
Sulfasalazine and leflunomide are both labeled for rheumatoid arthritis. Drugs@FDA records approvals of sulfasalazine since 1950 and of leflunomide since 1998. Pharmacies paid $0.199 per sulfasalazine 500 mg tablet and $0.324 per leflunomide 10 mg tablet (NADAC, October 7, 2026); the strengths differ, so the two prices are not like for like. In FDA's classes, sulfasalazine is an aminosalicylate and leflunomide an antirheumatic agent.
Check it at the source: the sulfasalazine FDA label on DailyMed (effective May 29, 2026); the leflunomide FDA label on DailyMed (effective June 4, 2025).
Highlights of the sulfasalazine record
Sulfasalazine (Azulfidine) · label of May 29, 2026
Used for
From the label: indicationsAZULFIDINE Tablets are indicated: • in the treatment of mild to moderate ulcerative colitis, and as adjunctive therapy in severe ulcerative colitis; and • for the prolongation of the remission period between acute attacks of ulcerative colitis.
On the market
- Earliest approval on file
- June 20, 1950
- Generic labelers
- 5 labelers
- Pharmacy cost
- $0.199 per tablet
Supply and safety
- Shortage
- No current entry
- Recalls
- 0
Highlights of the leflunomide record
Leflunomide (Arava) · label of June 4, 2025
EMBRYO-FETAL TOXICITY and HEPATOTOXICITY WARNING: EMBRYO-FETAL TOXICITY and HEPATOTOXICITY See full prescribing information for complete boxed warning. Embryo-Fetal Toxicity Teratogenicity and embryo-lethality occurred in animals administered leflunomide. ( 5.1 , 8.1 ) Exclude pregnancy prior to initiating ARAVA therapy. ( 5.1 , 8.3 ) Advise use of effective contraception in females of reproductive potential during treatment and during a drug elimination procedure.
Used for
From the label: indicationsARAVA is indicated for the treatment of adults with active rheumatoid arthritis (RA). ARAVA is a pyrimidine synthesis inhibitor indicated for the treatment of adults with active rheumatoid arthritis.
On the market
- Earliest approval on file
- September 10, 1998
- Generic labelers
- 16 labelers
- Pharmacy cost
- $0.324 per tablet
Supply and safety
- Shortage
- A presentation being discontinued
- Recalls
- 2
Source: FDA drug labels via openFDA (Sulfasalazine label of May 29, 2026, Leflunomide label of June 4, 2025); NDC Directory, Drugs@FDA, NADAC, FDA shortages and recalls (October 8, 2026)
How do sulfasalazine and leflunomide differ on the record?
In FDA's classes, sulfasalazine is an aminosalicylate and leflunomide an antirheumatic agent.
Half-life, in each label's words: Sulfasalazine, “The observed plasma half-life for intravenous sulfasalazine is 7.6 ± 3.4 hours.”; Leflunomide, “Due to the very long half-life of teriflunomide (18–19 days), a loading dose of 100 mg for 3 days was used in clinical …”
Only the leflunomide label carries a boxed warning.
Generics: sulfasalazine since 1973; leflunomide since 2005 (Drugs@FDA).
| Sulfasalazine | Leflunomide | |
|---|---|---|
| Labeled for | Crohn's disease and ulcerative colitis, Rheumatoid arthritis | Rheumatoid arthritis |
| Pharmacologic class | Aminosalicylate | Antirheumatic Agent |
| How it works (label) | n/a | Leflunomide is an isoxazole immunomodulatory agent that inhibits dihydroorotate dehydrogenase (a mitochondrial enzyme involved in de novo pyrimidine synthesis) and has antiproliferative activity. |
| Half-life (label) | The observed plasma half-life for intravenous sulfasalazine is 7.6 ± 3.4 hours. | Due to the very long half-life of teriflunomide (18–19 days), a loading dose of 100 mg for 3 days was used in clinical studies to facilitate the rapid attainment of steady-state teriflunomide concentrations. |
| Earliest approval on file (Drugs@FDA) | June 20, 1950 | September 10, 1998 |
| First generic approved | November 12, 1973 | September 13, 2005 |
| Generic labelers (NDC) | 5 labelers | 16 labelers |
| Pharmacy cost (NADAC, each one's most listed form; strengths differ) | $0.199 per tablet (Sulfasalazine 500 mg tablet) | $0.324 per tablet (Leflunomide 10 mg tablet) |
| 12-month price change | +10% | -7% |
| Boxed warning | No | Yes |
| Shortage now | No current entry | A presentation being discontinued |
| Recalls recorded | 0 | 2 |
| FAERS reports (a report is not proof of cause; counts follow how widely a medicine is used) | 77,784 | 104,036 |
| DEA schedule | none | none |
Source: Drugs@FDA, FDA NDC Directory, CMS NADAC of October 7, 2026, FDA shortages and recalls, FAERS via openFDA (FDA files October 8, 2026)
What next?
- Alternatives to sulfasalazine
- every medicine labeled for the same conditions