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Generic name: sulfasalazine
Brand names: Azulfidine, Azulfidine EN-tabs
Dosage form: oral tablet, oral delayed-release tablet
Drug classes: 5-aminosalicylates, Antirheumatics

Medically reviewed by Nicole France, BPharm. Last updated on May 11, 2022.

What is sulfasalazine?

Sulfasalazine is a disease-modifying anti-rheumatic drug (DMARD) used to treat and manage autoimmune diseases including rheumatoid arthritis and an inflammatory bowel disease called ulcerative colitis. It is a slow-acting DMARD, taking time to build up and start working.

Sulfasalazine helps to reduce pain and swelling and lowers inflammation in your body. It limits the damage that rheumatoid arthritis causes to your joints, helping to prevent disease progression.

Sulfasalazine consists of the anti-inflammatory agent 5-aminosalicylic acid (5-ASA, mesalamine or mesalazine) and the antibiotic sulfapyridine, which are linked by a bond.

It's not fully understood how sulfasalazine works. Sulfasalazine is too big to be absorbed by your small intestine, but bacteria in your colon can break the bond between 5-ASA and sulfapyridine, which frees 5-ASA to work locally in your colon to help in ulcerative colitis. Sulfasalazine and its metabolites - the other drugs that it is broken down into - are also thought to have a range of immunomodulatory effects. They block or inhibit certain processes in your body, which helps to reduce the activity of your immune system.

Sulfasalazine has been used since the 1950s. The US Food and Drug Administration (FDA) has approved a standard tablet (Azulfidine) and an enteric-coated, delayed-release tablet (Azulfidine EN-tabs) of sulfazalazine. Generic versions of these tablets are also available.

The delay-release, enteric-coated tablets are recommended for people who experience gastrointestinal side effects such as nausea and vomiting.

What is sulfasalazine used for?

Sulfasalazine is a prescription medication that is available as a standard tablet and as a delay-release, enteric-coated tablet.

Standard sulfasalazine tablets are used:

  • to treat mild to moderate ulcerative colitis.
  • as an add-on (adjunctive) therapy in severe ulcerative colitis.
  • to prolong periods of remission between acute attacks of ulcerative colitis.

Delay-release, enteric coated sulfasalazine tablets are used:

  • to treat mild to moderate ulcerative colitis, particularly in patients who cannot take standard, uncoated sulfasalazine tablets because of gastrointestinal side effects that is not caused by high blood levels of sulfapyridine and it's metabolites. This includes patients who experience nausea and vomiting with the first few doses and patients who continue to have symptoms when their dose is reduced.
  • as an add-on (adjunctive) therapy in severe ulcerative colitis.
  • to prolong periods of remission between acute attacks of ulcerative colitis.
  • to treat rheumatoid arthritis in patients who have responded inadequately to salicylates or other nonsteroidal anti-inflammatory drugs (NDAIDs).
  • to treat pediatric patients with polyarticular-course juvenile rheumatoid arthritis who have responded inadequately to salicylates or other NDAIDs.

Rest and and physiotherapy should also be continued in patients with rheumatoid arthritis or juvenile rheumatoid arthritis if recommended. Because sulfasalazine does not produce an immediate response, other analgesic and/or NSAIDs may still be needed until sulfasalazine starts working.

Sulfasalazine is also used 'off-label' - for conditions it is not approved for - for ankylosing spondylitis, Crohn's disease and psoriatic arthritis.

It is not known if sulfasalazine is safe and effective in children below the age of 2 years old.

Important information

Sulfasalazine can cause serious side effects including:

  • Hepatic, renal, and hematologic toxicity or other conditions
    Treatment with sulfasalazine has been reported to cause hypersensitivity reactions, agranulocytosis, aplastic anemia, other blood dyscrasias, renal and liver damage, irreversible neuromuscular and central nervous system changes, and fibrosing alveolitis, and these side effects have been linked to the death of some patients.
    Tell your doctor if you get a sore throat, fever, pallor, purpura, or jaundice while taking sulfasalazine. These symptoms may be signs of a serious blood disorder or hepatotoxicity (liver toxicity).
    Complete blood counts and urinalysis should be done frequently while on sulfasalazine. Treatment should be stopped while waiting for blood test results.
  • Oligospermia and Infertility
    Treatment with sulfasalazine may cause oligospermia (low sperm count) and infertility in men. Stopping sulfasalazine appears to reverse these effects.
  • Serious Infections
    Treatment with sulfasalazine may cause serious infections, including fatal sepsis and pneumonia. Tell your doctor straight away if you develop signs of an infection. Sulfasalazine treatment should be stopped if you develop a serious infection. Tests for infection and myelosuppression should be done if an infection is suspected.
  • Hypersensitivity Reactions
    Treatment with sulfasalazine may cause severe hypersensitivity reactions which may include internal organ involvement, such as hepatitis, nephritis, myocarditis, mononucleosis-like syndrome, hematological abnormalities, and/or pneumonitis including eosinophilic infiltration.
  • Severe Cutaneous Adverse Reactions
    • Drug Reactions with Eosinophilia and Systemic Symptoms (DRESS)
      Treatment with sulfasalazine can cause severe, life-threatening, systemic hypersensitivity reactions such as drug reaction with eosinophilia and systemic symptoms (DRESS). Early signs of such a reaction include fever or swollen lymph nodes (lymphadenopathy) and these may be seen even if a rash hasn't developed yet. Tell your doctor straight away if you develop signs of systemic hypersensitivity. Treatment with sulfasalazine should be stopped if another reason for your symptoms can't be identified.
    • Other Severe Cutaneous Adverse Reactions
      Treatment with sulfasalazine can cause other severe cutaneous adverse reactions, including exfoliative dermatitis, Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN), and acute generalized exanthematous pustulosis (AGEP). Severe cutaneous adverse reactions can be serious and are sometimes fatal. You are at highest risk for these events early in therapy, with most events occurring within the first month of treatment. Tell your doctor straight away if you develop symptoms of a severe cutaneous adverse reaction. Treatment with sulfasalazine should be stopped at the first sign of such reactions.

Who should not take sulfasalazine?

Do not take sulfaslazine if:

  • you are allergic to sulfaslazine, its metabolites, sulfonamides or salicylates or any of the other ingredients in sulfaslazine. See below for a complete list of ingredients.
  • you have intestinal or urinary obstruction
  • you have porphyria

What should I tell my doctor before taking sulfasalazine?

Before taking sulfasalazine you should tell your healthcare provider about all your medical conditions, including if you:

  • have a history of recurring or chronic infections
  • have underlying conditions or take other drugs which may make you more susceptible to infections
  • have severe allergy or bronchial asthma
  • have glucose-6-phosphate dehydrogenase deficiency

How should I take sulfasalazine?

  • Take sulfasalazine exactly as your doctor tells you to.
  • Take tablets in evenly divided doses, preferably after meals.
  • Take tablets with a full glass of water.
  • Swallow delayed-release, enteric-coated tablets whole. Do not break, crush or chew.
  • Your doctor will order frequent tests while you are on sulfasalazine.

What happens if I miss a dose?

If you miss a dose of sulfasalazine take your next dose as soon as you remember. If it is nearly time for your next dose, just take the next dose at the right time. Do not take double the dose.

What happens if I overdose?

If you take too much sulfasalazine seek emergency medical attention or call the Poison Help line at 1-800-222-1222.

Dosing information

The dose of sulfasalazine should be adjusted for each patient depending on their response and tolerance to the drug

Ulcerative Colitis

  • Initial Therapy
    The recommended dose for adults is sulfasalazine 3 to 4 g daily in evenly divided doses with dosage intervals not exceeding eight hours. A lower dose of 1 to 2 g may also be used to reduce the risk of gastrointestinal side effects.
    The recommended dose for children ≥ 6 years of age is 40 to 60 mg/kg of body weight in each 24-hour period, divided into 3 to 6 doses.
  • Maintenance Therapy
    The recommended dose for adults is sulfasalazine 2 g daily.
    The recommended dose for children ≥ 6 years of age is 30 mg/kg of body weight in each 24-hour period, divided into 4 doses.

Rheumatoid arthritis

  • The recommended dose for adults is 2 g daily in two evenly divided doses. Initially, a lower dose of 0.5 to 1 g daily should be used to reduce the risk of gastrointestinal side effects. A suggested dosing schedule is given below.

    Suggested Dosing Schedule for Adult Rheumatoid Arthritis:
    Week of treatment Morning No. of 500 mg tablets Evening No. of 500 mg tablets
    1 - 1
    2 1 1
    3 1 2
    4 2 2

Juvenile Rheumatoid Arthritis - polyarticular course

  • The recommended dose for children ≥ 6 years of age is 30 to 50 mg/kg of body weight daily in two evenly divided doses. Typically, the maximum dose is 2 g per day. Initially a dose of a quarter to a third of the planned maintenance dose should be used and increase weekly until reaching the maintenance dose at one month. This reduces the risk of gastrointestinal side effects.

See full prescribing information for further information about sulfasalazine dosing.

What are the side effects of sulfasalazine?

See "Important information" above.

The most common side effects of sulfasalazine are:

  • anorexia
  • headache
  • nausea
  • vomiting
  • gastric distress
  • reversible oligospermia.

Less frequent side effects are:

  • skin rash
  • pruritus
  • urticaria
  • fever
  • Heinz body anemia
  • hemolytic anemia
  • cyanosis

Sulfasalazine may also produce an orange-yellow discoloration of the urine or skin.

These are not all the possible side effects of sulfasalazine. For more information, ask your doctor or pharmacist.

Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.


Tell your doctor about all the medicines you take, including prescription and over-the-counter medicines, vitamins, and herbal supplements.

Especially tell your doctor if you take medicines that contain digoxin or folic acid. Sulfasalazine may reduce your absorption of these drugs. Sulfasalazine used in combination with methotrexate may increase your risk of gastrointestinal adverse events, especially nausea.

Know the medicines you take. Keep a list of them to show your doctor and pharmacist when you get a new medicine.

Pregnancy and breastfeeding

Tell your doctor if you are pregnant or plan to become pregnant. A study suggests that treatment with sulfasalazine is not associated with fetal malformation. However, neural tube defects have been reported in some infants born to mothers taking sulfasalazine during pregnancy. This may be linked to the drug's ability to inhibit the absorption and metabolism of folic acid. Sulfasalazine and sulfpyridine pass through the placenta. It is recommended that sulfasalazine is only used during pregnancy if clearly needed.

Tell your doctor if you are breastfeeding or planning to breastfeed. Sulfasalazine and its metabolite pass into breast milk and can lead to a type of brain damage called kernicterus in newborns. Limited data also suggests it may cause infants to develop bloody stools or diarrhea. Sulfasalazine should be used with caution in people who are breastfeeding. Talk to your doctor about the best way to feed your baby while on sulfasalazine.


  • Store at 25°C (77°F); excursions permitted to 15–30°C (59–86°F).

Keep out of reach of children.

What are the ingredients in sulfasalazine?

Active ingredients: sulfasalazine

Inactive ingredients:

Azulfidine tablets: magnesium stearate, unspecified povidone, silicon dioxide, corn starch

Azulfidine EN-tabs (enteric coated, delayed-release tablets): white wax, carnauba wax, cellacefate, magnesium stearate, polyethylene glycol 20000, unspecified povidone, propylene glycol, glyceryl stearate SE, silicon dioxide, corn starch, talc

Generic versions of sulfasalazine may contain different inactive ingredients. Check the product label for your particular formulation of sulfasalazine for a complete list of ingredients.

Sulfasalazine is distributed under the brand names Azulfidine and Azulfidine EN-tabs by Pfizer Labs, Division of Pfizer Inc. New York, NY 10017. Other companies also produce generic versions of the drug.

Popular FAQ

Does sulfasalazine suppress the immune system?

Sulfasalazine may suppress your immune system by lowering white blood cell counts. Serious or fatal infections can occur. If you come down with signs or symptoms of an infection such as fever, chills, shortness of breath, cough, paleness, sore throat, mouth sores, redness or swelling, contact your doctor right away.

What are the long-term effects of taking sulfasalazine?

Long-term side effects with sulfasalazine may include serious allergic reactions, low blood cell counts, infections, heart, liver and kidney damage, nerve or muscle problems, low sperm count, sun sensitivity and severe skin reactions. Your urine or skin may turn orange colored but is usually harmless and goes away when medicine is stopped.

Does sulfasalazine cause weight gain?

Sulfasalazine may cause kidney problems that lead to fluid build-up in your body and weight gain. You may have puffy eyes or swelling in your arms, ankles or feet, or little or no urination. Call your doctor right away if you have any of these side effects.

How long does sulfasalazine stay in your system?

Oral sulfasalazine is mainly broken down in your intestines to the more active agent sulfapyridine. It takes 1.5 to 2 days to get sulfasalazine out of your system, and 2 to 3.5 days for sulfapyridine. Results can vary due to many factors, including your age, health, how fast you metabolize, and drug route and dose.

Does sulfasalazine cause hair loss?

Hair loss (alopecia) has been reported with sulfasalazine in one case report of a severe allergic reaction (Drug Rash with Eosinophilia and Systemic Symptoms or “DRESS”), but is not a common side effect. Autoimmune conditions, such as rheumatoid arthritis (RA) and lupus, can be associated with hair loss.

Is sulfasalazine a steroid drug?

No, sulfasalazine is not a steroid medication like prednisone or prednisolone, but can lower inflammation in certain diseases and help prevent the need for steroids. It is classified as an oral 5-aminosalicylate agent and is used for conditions like ulcerative colitis and rheumatoid arthritis.

Does sulfasalazine cause high blood pressure?

Sulfasalazine has not been found to be associated with high blood pressure (hypertension) in a clinical research study. Also, the manufacturer’s product information does not list high blood pressure as a side effect. Common side effects with sulfasalazine include loss of appetite, headache, vomiting, and upset stomach.

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.