Sulfasalazine: Side Effects, Interactions, and Uses

What is Sulfasalazine?

A prodrug: sulfasalazine, is used in the treatment of chronic inflammatory bowel disease and to treat rheumatoid arthritis as second-line therapy. It’s composed of sulfapyridine and 5-aminosalicylic acid (5-ASA) connected by an azo bond, which is broken by bacteria in the distal ileum and colon to release the active ingredients. In the United States, 5-ASA is referred to as mesalamine, while in the United Kingdom, it is referred to as mesalazine.

Drug Class

Sulfasalazine belongs to the drug class known as Disease-modifying anti-rheumatic drugs.

What is sulfasalazine prescribed for?

Sulfapyridine and 5-aminosalicylic acid (active chemicals) is prescribed for the therapy of rheumatoid arthritis and ulcerative colitis, respectively, and are found in the distal small bowel and colonic metabolites of sulfasalazine.


In the small intestine, about 20% of sulfasalazine is absorbed unaltered. The majority of sulfapyridine and roughly 25% of 5-ASA are absorbed after cleavage in the colon. Sulfapyridine concentrations may be higher in slow acetylates. In the colon, it is hydrolyzed by bacteria into sulfapyridine and 5-aminosalicylic acid, which are then removed primarily through acetylation/glucuronidation and bile, respectively. 95-99% of the drug is bound to plasma proteins. Sulfasalazine shows a half-life of approximately 6 to 14 hours. The drug is primarily eliminated through metabolism. Small amounts of the drug are excreted through bile. In patients with renal impairment, there have been shreds of evidence of reduced drug excretion.

Sulfasalazine Mechanism of Action

The pharmacological effects of sulfasalazine are mainly attributable to its breakdown products sulfapyridine and 5-aminosalicylic acid, which have anti-inflammatory, immunosuppressive, and antibacterial properties. The exact mechanism by which it works is uncertain. By functioning as a competitive antagonist for aminobenzoic acid, sulfapyridine destroys microorganisms. Although the mechanism of action of 5-aminosalicylic acid is unknown, it is an anti-inflammatory drug. Lipoxygenase, cyclooxygenase, and other folate metabolizing enzymes are thought to be inhibited by it. Sulfasalazine reduces T-cell proliferation and B-cell activation by inhibiting adhesion molecule up-regulation on monocytes and granulocytes produced by TNF-alpha.


Sulfasalazine is contraindicated in hypersensitivity to salicylates and sulphonamides, as well as moderate to severe renal impairment.

Other contraindications include:

  • Megaloblastic anemia
  • G6PD deficiency
  • Hepatic illness
  • Porphyria
  • Asthma
  • Severe allergy diseases
  • Children under the age of two

Sulfasalazine Side Effects

Common Side effects

  • Loss of appetite
  • Diarrhea
  • Nausea
  • Headache

Other Side effects

  • Exacerbation of symptoms of colitis
  • Fever
  • Hypersensitivity reactions
  • Lung complications
  • Ocular complications
  • Stomatitis
  • Parotitis
  • Ataxia
  • Aseptic meningitis
  • Vertigo
  • Tinnitus
  • Alopecia
  • Peripheral neuropathy,
  • Insomnia
  • Depression
  • Hallucinations
  • Kidney reactions
  • Oligospermia
  • Infertility
  • Orange urine
  • Staining of soft contact lenses
sulfasalazine side effects

Rare side effects

  • Acute pancreatitis
  • Hepatitis
  • Nephrotic syndrome
  • Blood disorders
  • Sulfapyridine passes into breast milk

Sulfasalazine Interactions

It shows interactions with the following agents

  • Digoxin
  • Azathioprine
  • Mercaptopurine
  • Oral contraceptive

Sulfasalazine Uses

It is used to treat

  • Chronic inflammatory bowel diseases
  • Rheumatoid arthritis

What does sulfasalazine do to the body?

It reduces inflammation in the colon by acting locally. It also operates throughout the body by preventing the creation of prostaglandins, a type of chemical. Prostaglandins serve a variety of functions in the body, including pain and inflammation management.

Is sulfasalazine a steroid?

The steroid-sparing effects of sulfasalazine and 5-ASA medications are comparable. In ulcerative colitis patients, disease-specific hospitalizations are 100 times more likely than major adverse medication effects. As a result, drug efficacy should take precedence in the selection of therapeutic agents.

Sulfasalazine Brand Names


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