What Is Sulfasalazine Used For?

Sulfasalazine is used to treat a certain type of bowel disease called ulcerative colitis. This medication does not cure this condition, but it helps decrease symptoms such as fever, stomach pain, diarrhea, and rectal bleeding. After an attack is treated, sulfasalazine is also used to increase the amount of time between attacks. Sulfasalazine works by reducing irritation and swelling in the large intestines. In addition, delayed-release tablets of sulfasalazine are used to treat rheumatoid arthritis. Sulfasalazine helps to reduce joint pain, swelling, and stiffness. Early treatment of rheumatoid arthritis with sulfasalazine helps to reduce/prevent further joint damage so you can do more of your normal daily activities. This medication is used with other drugs, rest, and physical therapy in patients who have not responded to other medications (salicylates, nonsteroidal anti-inflammatory drugs-NSAIDs).

Sulfasalazine may also be used to treat another type of bowel disease called Crohn's disease.

Sulfasalazine is available under the following different brand names: Azulfidine, and Azulfidine EN.

Dosages of Sulfasalazine

  • Adult and Pediatric Dosage Forms and Strengths
  • Tablet
  • 500 mg
  • Tablet, enteric coated (delayed release)
  • 500 mg

Dosage Considerations – Should be Given as Follows:

Ulcerative Colitis

  • Mild to moderate cases, adjunctive therapy in severe cases, and prolongation of remission
  • Adult: 3-4 g/day orally divided three times daily after meals; may start 1-2 g once/day
  • Children under 6 years old: Safety and efficacy not established
  • Children 6 years or older
    • Initial: 40-60 mg/kg/day orally divided every 4-8 hours after meals
    • Maintenance: 30 mg/kg/day orally divided every 6 hours after meals

Rheumatoid Arthritis

  • Inadequate response or intolerance to salicylates or other nonsteroidal anti-inflammatory drugs (NSAIDs)
  • Enteric coated: 2-3 g/day orally divided three times daily after meals; may start 0.5-1 g once/day

Juvenile Rheumatoid Arthritis

  • Polyarticular course with inadequate response to salicylates or other nonsteroidal anti-inflammatory drugs (NSAIDs)
  • Children under 6 years old: Safety and efficacy not established
  • Children 6 years or older: Gradually titrate at weekly intervals up to 30-50 mg/kg/day orally divided twice daily after meals; not to exceed 2 g/day

Crohn's Disease (Off-label)

  • 3-6 g/day orally divided three times daily after meals


  • Take after meals
  • Administer in equally divided doses

What Are Side Effects Associated with Using Sulfasalazine?

Common side effects of sulfasalazine include:

  • Loss of appetite
  • Headache
  • Nausea
  • Vomiting
  • Gastric distress/stomach upset
  • Temporary, reversible male infertility
  • Diarrhea
  • Ringing in your ears (tinnitus)
  • Dizziness
  • Spinning sensation (vertigo)
  • Unusual tiredness
  • White patches or sores inside your mouth or on your lips
  • Sleep problems (insomnia)

Less common side effects of sulfasalazine include:

Serious side effects of sulfasalazine include:

  • Sun sensitivity
  • Hearing changes
  • Mental/mood changes
  • Painful urination
  • Blood in the urine
  • Changes in the amount of urine
  • New lump or growth in the neck (goiter)
  • Numbness or tingling of the hands or feet
  • Signs of low blood sugar (e.g., hunger, cold sweat, blurred vision, weakness, fast heartbeat)
  • Swollen glands

Postmarketing side effects of sulfasalazine reported include:

This is not a complete list of side effects and other serious side effects may occur. Call your doctor for information and medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

What Other Drugs Interact with Sulfasalazine?

If your doctor has directed you to use this medication for your condition, your doctor or pharmacist may already be aware of any possible drug interactions or side effects and may be monitoring you for them. Do not start, stop, or change the dosage of this medicine or any medicine before getting further information from your doctor, healthcare provider or pharmacist first.

  • Sulfasalazine has no known severe interactions with other drugs.
  • Serious interactions of sulfasalazine include:
  • Sulfasalazine has moderate interactions with at least 215 different drugs.
  • Sulfasalazine has mild interactions with at least 124 different drugs.

This document does not contain all possible interactions. Therefore, before using this product, tell your doctor or pharmacist of all the products you use. Keep a list of all your medications with you, and share the list with your doctor and pharmacist. Check with your physician if you have health questions or concerns.

What Are Warnings and Precautions for Sulfasalazine?


This medication contains sulfasalazine. Do not take Azulfidine or Azulfidine EN if you are allergic to sulfasalazine or any ingredients contained in this drug.

Keep out of reach of children. In case of overdose, get medical help or contact a Poison Control Center immediately.


Effects of Drug Abuse

  • No information available

Short-Term Effects

  • See "What Are Side Effects Associated with Using Sulfasalazine?"

Long-Term Effects

  • See "What Are Side Effects Associated with Using Sulfasalazine?"


  • Severe allergy or bronchial asthma.
  • Blood dyscrasias; serious infections reported, including fatal sepsis and pneumonia; some infections were associated with agranulocytosis, neutropenia, or myelosuppression.
  • Serious skin reactions, some of them fatal, including exfoliative dermatitis, Stevens-Johnson syndrome, and toxic epidermal necrolysis.
  • Severe hypersensitivity reported; may include internal organ involvement, such as hepatitis, nephritis, myocarditis, mononucleosis-like syndrome (i.e., pseudomononucleosis), hematological abnormalities (including hematophagic histiocytosis), and/or pneumonitis including eosinophilic infiltrat.
  • Anemia.
  • Gout.
  • Hepatic/renal impairment.
  • Hypochlorhydria.
  • Hypoprothrombinemia.
  • Thyrotoxicosis.
  • Vitamin K deficiency.
  • Ensure adequate hydration to prevent crystalluria.
  • May cause orange discoloration of the urine or skin.

Pregnancy and Lactation

  • Sulfasalazine may be acceptable for use during pregnancy. Either animal studies show no risk but human studies are not available or animal studies showed minor risks and human studies were done and showed no risk.
  • If used for prolonged periods or near term, use sulfasalazine only in LIFE-THREATENING emergencies during pregnancy when no safer drug is available. There is positive evidence of human fetal risk. There is increased potential for kernicterus in the newborn.
  • Oral sulfasalazine inhibits the absorption and metabolism of folic acid, which may interfere with folic acid supplementation and protection from neural tube defects.
  • Sulfasalazine is excreted into human breast milk. Use caution with breastfeeding. There are some reports of bloody stools or diarrhea in human milk fed infants of mothers taking sulfasalazine.
Medscape. Sulfasalazine.
RxList. Azulfidine Side Effects Drug Center.

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