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Clinical data
Trade namesAzulfidine, Salazopyrin, Sulazine, others
Other namesSulphasalazine, SSZ
License data
Routes of
By mouth
Drug classSulfonamides
ATC code
Legal status
Legal status
Pharmacokinetic data
Elimination half-life5-10 hours
Excretiondrug metabolites are excreted in urine and feces [4]
  • 2-hydroxy-5-[(E)-2-{4-[(pyridin-2-yl)sulfamoyl]phenyl}diazen-1-yl]benzoic acid
CAS Number
PubChem CID
CompTox Dashboard (EPA)
ECHA InfoCard100.009.069 Edit this at Wikidata
Chemical and physical data
Molar mass398.39 g·mol−1
3D model (JSmol)
Melting point240 to 245 °C (464 to 473 °F) (dec.)
  • C1=CC=NC(=C1)NS(=O)(=O)C2=CC=C(C=C2)N=NC3=CC(=C(C=C3)O)C(=O)O
  • InChI=1S/C18H14N4O5S/c23-16-9-6-13(11-15(16)18(24)25)21-20-12-4-7-14(8-5-12)28(26,27)22-17-3-1-2-10-19-17/h1-11,23H,(H,19,22)(H,24,25) checkY
 ☒NcheckY (what is this?)  (verify)

Sulfasalazine, sold under the brand name Azulfidine among others, is a medication used to treat rheumatoid arthritis, ulcerative colitis, and Crohn's disease.[5] It is considered by some to be a first-line treatment in rheumatoid arthritis.[6] It is taken by mouth or can be administered rectally.[5]

Significant side effects occur in about 25% of people.[6] Commonly these include loss of appetite, nausea, headache, and rash.[5] Severe side effects include bone marrow suppression, liver problems, Stevens–Johnson syndrome, and kidney problems.[6][7][4] It should not be used in people allergic to aspirin or sulfonamide.[6] Use during pregnancy appears to be safe for the baby.[5]

Sulfasalazine is in the disease-modifying antirheumatic drugs (DMARDs) family of medications.[5] It is unclear exactly how it works.[5] One proposed mechanism is the inhibition of prostaglandins, resulting in local anti-inflammatory effects in the colon.[4] The medication is broken down by intestinal bacteria into sulfapyridine and 5-aminosalicylic acid.[5]

Sulfasalazine was approved for medical use in the United States in 1950.[5] It is on the World Health Organization's List of Essential Medicines.[8] Sulfasalazine is available as a generic medication.[5] In 2020, it was the 284th most commonly prescribed medication in the United States, with more than 1 million prescriptions.[9][10]

Medical uses[edit]

Sulfasalazine is used in the treatment of inflammatory bowel disease, including ulcerative colitis and Crohn's disease. It is also indicated for use in rheumatoid arthritis and used in other types of inflammatory arthritis (e.g. psoriatic arthritis and reactive arthritis).[11][3][2]

It is usually not given to children under two years of age.[3][2]

Side effects[edit]

Use of sulfasalazine is contraindicated in people with sulfa allergies and in those with urinary tract obstructions, intestinal obstructions, and severe liver or kidney problems.[4]

Sulfasalazine metabolizes to sulfapyridine. Serum levels should be monitored every three months, and more frequently at the outset. Serum levels above 50 μg/L are associated with side effects. In rare cases, sulfasalazine can cause severe depression in young males. It can also cause oligospermia and temporary infertility. Immune thrombocytopenia has been reported.[12]

Sulfasalazine inhibits dihydropteroate synthase, and can cause folate deficiency and megaloblastic anemia.[13][14][15] and various other undesirable effects.[16]

Sulfasalazine can cause hemolytic anemia in people with G6PD deficiency.[17]

Sulfasalazine can cause kidney stones.[18] Sulfasalazine may cause stomach upset, nausea, vomiting, loss of appetite, headache, dizziness, or unusual tiredness.[5] Skin and urine can become orange, with occasional allergic reactions.[19][5]

Sulfasalazine may cause sulfhemoglobinemia.[citation needed]


Around 90% of a dose of sulfasalazine reaches the colon, where most of it is metabolized by bacteria into sulfapyridine and mesalazine (also known as 5-aminosalicylic acid or 5-ASA). Both metabolites are active; most of the sulfapyridine is absorbed and then further metabolized, but most mesalazine is not, and remains in the colon.[3]

A mix of unchanged, hydroxylated, and glucuronidated sulfapyridine is eliminated in urine, as is acetylated mesalazine and unmetabolized sulfasalazine.[3][2]

The mechanism of action is not clear, but it appears that sulfasalazine and its metabolites have immunosuppressive, antibacterial, and anti-inflammatory effects.[11][3] It also appears to inhibit the cystine-glutamate antiporter,[20] as well as sepiapterin reductase.[21]


It is a codrug which is a combination of sulfapyridine and 5-aminosalicylic acid coupled with an azo linkage.


In people with rheumatoid arthritis, the cost-effectiveness of sulfasalazine is improved by combining it with other drugs.[22] It is commonly used in treating inflammatory bowel disease in part due to its cost effectiveness.[23]


Sulfasalazine has been studied in cirrhosis,[24] psoriasis,[25] idiopathic urticaria,[26] and amyloidosis.[27]


  1. ^ "Sulfasalazine Use During Pregnancy". 9 November 2018. Retrieved 24 January 2020.
  2. ^ a b c d "Sulfasalazine 250mg/5ml Oral Suspension - Summary of Product Characteristics (SmPC)". electronic medicines compendium (emc). 13 September 2019. Retrieved 4 December 2019.
  3. ^ a b c d e f "Salazopyrin Tablets - Summary of Product Characteristics". electronic medicines compendium (emc). February 2014. Archived from the original on 16 April 2017.
  4. ^ a b c d Vallerand AH, Sanoski CA, Deglin JH (5 June 2014). Davis's drug guide for nurses (Fourteenth ed.). Philadelphia. ISBN 978-0-8036-4085-6. OCLC 881473728.{{cite book}}: CS1 maint: location missing publisher (link)
  5. ^ a b c d e f g h i j k "Sulfasalazine". The American Society of Health-System Pharmacists. Archived from the original on 21 December 2016. Retrieved 8 December 2016.
  6. ^ a b c d World Health Organization (2009). Stuart MC, Kouimtzi M, Hill SR (eds.). WHO Model Formulary 2008. World Health Organization. pp. 41, 45. hdl:10665/44053. ISBN 9789241547659.
  7. ^ Hamilton R (2015). Tarascon Pocket Pharmacopoeia 2015 Deluxe Lab-Coat Edition. Jones & Bartlett Learning. p. 464. ISBN 9781284057560.
  8. ^ World Health Organization (2019). World Health Organization model list of essential medicines: 21st list 2019. Geneva: World Health Organization. hdl:10665/325771. WHO/MVP/EMP/IAU/2019.06. License: CC BY-NC-SA 3.0 IGO.
  9. ^ "The Top 300 of 2020". ClinCalc. Retrieved 7 October 2022.
  10. ^ "Sulfasalazine - Drug Usage Statistics". ClinCalc. Retrieved 7 October 2022.
  11. ^ a b "Azulfidine- sulfasalazine tablet". DailyMed. 8 May 2019. Archived from the original on 29 October 2015. Retrieved 24 January 2020.
  12. ^ Cantarini L, Tinazzi I, Biasi D, Fioravanti A, Galeazzi M (June 2007). "Sulfasalazine-induced immune thrombocytopenia". Postgraduate Medical Journal. 83 (980): e1. doi:10.1136/pgmj.2006.055194. PMC 2600053. PMID 17551063.
  13. ^ Inflammatory Bowel Disease~workup at eMedicine
  14. ^ Women With Autoimmune Diseases: Medications During Pregnancy and Lactation: Sulfasalazine; "Women with Autoimmune Diseases: Medications During Pregnancy and Lactation: Sulfasalazine". Archived from the original on 21 October 2011. Retrieved 8 March 2012.
  15. ^ Hernández-Díaz S, Werler MM, Walker AM, Mitchell AA (November 2000). "Folic acid antagonists during pregnancy and the risk of birth defects". The New England Journal of Medicine. 343 (22): 1608–1614. doi:10.1056/NEJM200011303432204. PMID 11096168.
  16. ^ Dixon SJ, Patel DN, Welsch M, Skouta R, Lee ED, Hayano M, et al. (May 2014). "Pharmacological inhibition of cystine-glutamate exchange induces endoplasmic reticulum stress and ferroptosis". eLife. 3: e02523. doi:10.7554/eLife.02523. PMC 4054777. PMID 24844246.
  17. ^ "SulfaSALAzine: Drug Information Provided by Lexi-Comp". Merck & Co., Inc. January 2012. Archived from the original on 29 August 2011. Retrieved 28 July 2012.{{cite web}}: CS1 maint: unfit URL (link)
  18. ^ De Koninck AS, Groen LA, Maes H, Verstraete AG, Stove V, Delanghe JR (2016). "An Unusual Type of Kidney Stone". Clinical Laboratory. 62 (1–2): 235–239. doi:10.7754/Clin.Lab.2015.150605. hdl:1854/LU-6847821. PMID 27012055.
  19. ^ "Sulfasalazine". WebMD. Archived from the original on 26 January 2016.
  20. ^ Bridges RJ, Natale NR, Patel SA (January 2012). "System xc⁻ cystine/glutamate antiporter: an update on molecular pharmacology and roles within the CNS". British Journal of Pharmacology. 165 (1): 20–34. doi:10.1111/j.1476-5381.2011.01480.x. PMC 3252963. PMID 21564084.
  21. ^ Costigan M, Latremoliere A, Woolf CJ (February 2012). "Analgesia by inhibiting tetrahydrobiopterin synthesis". Current Opinion in Pharmacology. 12 (1): 92–99. doi:10.1016/j.coph.2011.10.019. PMC 3288148. PMID 22178186.
  22. ^ Benucci M, Saviola G, Manfredi M, Sarzi-Puttini P, Atzeni F (2011). "Cost effectiveness analysis of disease-modifying antirheumatic drugs in rheumatoid arthritis. A systematic review literature". International Journal of Rheumatology. 2011: 845496. doi:10.1155/2011/845496. PMC 3228304. PMID 22162693.
  23. ^ Baumgart DC (2017). Crohn's Disease and Ulcerative Colitis: From Epidemiology and Immunobiology to a Rational Diagnostic and Therapeutic Approach. Springer. p. 395. ISBN 978-3-319-33703-6.
  24. ^ Oakley F, Meso M, Iredale JP, Green K, Marek CJ, Zhou X, et al. (January 2005). "Inhibition of inhibitor of kappaB kinases stimulates hepatic stellate cell apoptosis and accelerated recovery from rat liver fibrosis". Gastroenterology. 128 (1): 108–120. doi:10.1053/j.gastro.2004.10.003. PMID 15633128.
  25. ^ Gupta AK, Ellis CN, Siegel MT, Duell EA, Griffiths CE, Hamilton TA, et al. (April 1990). "Sulfasalazine improves psoriasis. A double-blind analysis". Archives of Dermatology. 126 (4): 487–493. doi:10.1001/archderm.1990.01670280071013. PMID 1690970.
  26. ^ McGirt LY, Vasagar K, Gober LM, Saini SS, Beck LA (October 2006). "Successful treatment of recalcitrant chronic idiopathic urticaria with sulfasalazine". Archives of Dermatology. 142 (10): 1337–1342. doi:10.1001/archderm.142.10.1337. PMID 17043190.
  27. ^ Brumshtein B, Esswein SR, Salwinski L, Phillips ML, Ly AT, Cascio D, et al. (November 2015). "Inhibition by small-molecule ligands of formation of amyloid fibrils of an immunoglobulin light chain variable domain". eLife. 4: e10935. doi:10.7554/eLife.10935. PMC 4758944. PMID 26576950.

External links[edit]

  • "Sulfasalazine". Drug Information Portal. U.S. National Library of Medicine.