Sulfasalazine: uses, dosing, side effects & brands
Sulfasalazine is an aminosalicylate sold in the U.S. under 2 brand and generic names, for juvenile arthritis, rheumatoid arthritis and ulcerative colitis. Below: what the FDA label says, every product that contains it, what the pills look like, and its recall record.
Key facts
- Drug class
- Aminosalicylate
- Treats (across its forms)
- Juvenile Arthritis, Rheumatoid Arthritis and Ulcerative Colitis
- Available as
- Tablet, delayed release · Tablet
- Sold as
- 2 products — Azulfidine En-Tabs and Azulfidine
- Prescription?
- Prescription only
- Generic available?
- Not in our catalog
- What the pharmacy pays
- about $6 for a 30-count supply — not your price
How Azulfidine En-Tabs is dosed
From the FDA label for Azulfidine En-Tabs (application NDA007073). Other sulfasalazine products — different forms, different strengths — are dosed differently. Follow the label for the one you were prescribed.
The dosage of sulfasalazine delayed release tablets should be adjusted to each individual's response and tolerance. Patients should be instructed to take sulfasalazine delayed release tablets in evenly divided doses, preferably after meals, and to swallow the tablets whole. Ulcerative Colitis Initial Therapy: Adults: 3 to 4 g daily in evenly divided doses with dosage intervals not exceeding eight hours. It may be advisable to initiate therapy with a lower dosage, e.g., 1 to 2 g daily, to reduce possible gastrointestinal intolerance. If daily doses exceeding 4 g are required to achieve the desired therapeutic effect, the increased risk of toxicity should be kept in mind. Children, six years of age and older: 40 to 60 mg/kg of body weight in each 24-hour period, divided into 3 to 6 doses. Maintenance Therapy: Adults: 2 g daily. Children, six years of age and older: 30 mg/kg of body weight in each 24-hour period, divided into 4 doses. The response of acute ulcerative colitis to sulfasalazine delayed release tablets can be evaluated by clinical criteria, including the presence of fever, weight changes, and degree and frequency of diarrhea and bleeding, as well as by sigmoidoscopy and the evaluation of biopsy samples. It is often necessary to continue medication even when clinical symptoms, including diarrhea, have been controlled. When endoscopic examination confirms satisfactory…
Everything below is the FDA label for Azulfidine En-Tabs (tablet, delayed release). Sulfasalazine is also sold as tablet, and those are different medicines to take — follow the label for the one you were prescribed.
Azulfidine En-Tabs side effects
The most common adverse reactions associated with sulfasalazine in ulcerative colitis are anorexia, headache, nausea, vomiting, gastric distress, and apparently reversible oligospermia. These occur in about one-third of the patients. Less frequent adverse reactions are pruritus, urticaria, rash, fever, Heinz body anemia, hemolytic anemia, and cyanosis, which may occur at a frequency of 1 in 30 patients or less. Experience suggests that with a daily dose of 4 g or more, or total serum sulfapyridine levels above 50 µg/mL, the incidence of adverse reactions tends to increase. Similar adverse reactions are associated with sulfasalazine use in adult rheumatoid arthritis, although there was a greater incidence of some reactions. In rheumatoid arthritis studies, the following common adverse reactions were noted: nausea (19%), dyspepsia (13%), rash (13%), headache (9%), abdominal pain (8%), vomiting (8%), fever (5%), dizziness (4%), stomatitis (4%), pruritis (4%), abnormal liver function tests (4%), leukopenia (3%), and thrombocytopenia (1%). One report 7 showed a 10% rate of immunoglobulin suppression, which was slowly reversible and rarely accompanied by clinical findings. In general, the adverse reactions in juvenile rheumatoid arthritis patients are similar to those seen in patients with adult rheumatoid arthritis except for a high frequency of serum sickness-like syndrome in…
Who shouldn’t take Azulfidine En-Tabs
Sulfasalazine delayed release tablets are contraindicated in: Hypersensitivity to sulfasalazine, its metabolites, sulfonamides or salicylates, Patients with intestinal or urinary obstruction, Patients with porphyria, as the sulfonamides have been reported to precipitate an acute attack.
Azulfidine En-Tabs drug interactions
Reduced absorption of folic acid and digoxin have been reported when those agents were administered concomitantly with sulfasalazine. When daily doses of sulfasalazine 2 g and weekly doses of methotrexate 7.5 mg were coadministered to 15 rheumatoid arthritis patients in a drug-drug interaction study, the pharmacokinetic disposition of the drugs was not altered. Daily doses of sulfasalazine 2 g (maximum 3 g) and weekly doses of methotrexate 7.5 mg (maximum 15 mg) were administered alone or in combination to 310 rheumatoid arthritis patients in two controlled 52-week clinical studies. The overall toxicity profile of the combination revealed an increased incidence of gastrointestinal adverse events, especially nausea, when compared to the incidence associated with either drug administered alone.
Every sulfasalazine product we track (2)
Same active ingredient — different manufacturer, form, price and FDA recall record. That last one is what our independent score measures.
| # | Drug | Rating | Type | Form | Generic? | Pharmacy pays | |
|---|---|---|---|---|---|---|---|
| 1 | 64/100 | Prescription | Tablet | Generic | $6 | View → | |
| 2 | Not yet rated | Prescription | Tablet | Generic | $6 | View → |
What sulfasalazine pills look like
Imprint codes, colour and shape from the FDA’s labelling data. Match the imprint on your pill — or search any imprint.
How long sulfasalazine keeps
No sulfasalazine label we read sets a separate limit for after opening, but they do specify how it must be stored — and the stability behind any date assumes those conditions.
Does sulfasalazine expire? The in-use limits and storage rules from its labelsSulfasalazine and breastfeeding
From LactMed, the US National Library of Medicine’s Drugs and Lactation Database — quoted, not rewritten.
Full LactMed record for sulfasalazine: levels in milk, effects in breastfed infants, and the drugs it would consider insteadSulfasalazine and its active metabolite mesalamine are poorly excreted into breastmilk. However, rather high levels of the mesalamine metabolite N-acetyl-5-ASA appear in breastmilk and its effects on breastfed infants are unknown. Another sulfasalazine metabolite, sulfapyridine, also appears in milk and infant serum and might cause hemolysis, especially in newborn infants and in those with glucose-6-phosphate dehydrogenase (G6PD) deficiency. The time of greatest risk for hemolysis in fullterm newborns without G6PD deficiency might be as short as 8 days after birth. Bloody diarrhea has occurred in an infant whose mother was taking sulfasalazine and a few cases of diarrhea have been reported in infants exposed to mesalamine in breastmilk, although the rate is not high. Numerous experts and professional guidelines have stated that the drug is a low risk to the nursing infant and acceptable to use during breastfeeding. If the mother requires sulfasalazine, it is not a reason to discontinue breastfeeding, but carefully observe breastfed infants for diarrhea. Other mesalamine derivatives that do not contain a sulfonamide are preferred.
National Institute of Child Health and Human Development, record revised December 15, 2025. LactMed states its information is not a substitute for professional judgement.
What people report to the FDA about sulfasalazine
The FDA Adverse Event Reporting System (FAERS) collects reports from patients and clinicians. It holds 74,482 reports naming sulfasalazine, and the FDA flagged 84% of those reports as serious. The effects reported most often — leaving out reports about overdose, misuse or the condition being treated, which dominate the raw list for common medicines:
- rheumatoid arthritis19,226 reports
- drug intolerance13,646 reports
- arthralgia13,197 reports
- fatigue13,142 reports
- joint swelling12,594 reports
- rash10,732 reports
- abdominal discomfort9,925 reports
- contraindicated product administered9,531 reports
Read these as a signal, not a rate. A report does not mean sulfasalazine caused the effect — anyone can file one, and many describe people taking several medicines for several conditions. Crucially there is no denominator: FAERS does not record how many people took the drug, so these counts cannot be turned into “X% of patients” — a bigger number often just means a more widely used or more talked-about drug. Duplicates exist, and publicity drives reporting. For what is actually established, read the FDA label section above.
Source: openFDA drug/event (FAERS), retrieved July 26, 2026.
Related calculators
Frequently asked questions
What is Azulfidine En-Tabs?
Sulfasalazine delayed release tablets contain sulfasalazine, formulated in a delayed release tablet (enteric-coated), 500 mg, for oral administration. Sulfasalazine delayed release tablets are film coated with cellulose acetate phthalate to retard disintegration of the tablet in the stomach and reduce potential irritation of the gastric mucosa. Therapeutic Classification: Anti-inflammatory agent and/or immunomodulatory agent. Chemical Designation: 5-([p-(2-pyridylsulfamoyl)phenyl]azo) salicylic acid.
What kind of drug is sulfasalazine?
The FDA classifies sulfasalazine as an aminosalicylate. Aminosalicylates (5-ASA drugs like mesalamine) act directly on the inflamed lining of the colon, where they are thought to calm the local inflammatory response by blocking several inflammation-driving chemicals and mopping up tissue-damaging free radicals, which helps the gut heal in ulcerative colitis. If you are checking whether it is safe to combine with something else, the class is what matters — two drugs from the same class usually should not be stacked.
Can you take sulfasalazine with other medicines?
It depends on the medicine. We check it against the FDA labels rather than guessing: our interaction checker searches each drug's own label for the other and quotes what it says, naming the section it came from. Run sulfasalazine against whatever else you take — and remember that a label not naming a drug is not the same as that combination being safe.
What brand names is sulfasalazine sold under?
We track 2 sulfasalazine-containing products in the U.S.: Azulfidine En-Tabs and Azulfidine. They are the same active ingredient; they differ in form, manufacturer, price and FDA recall record.
What forms does sulfasalazine come in?
Across the brands we track, sulfasalazine is currently marketed as tablet, delayed release and tablet, per the FDA's National Drug Code Directory. Each form is dosed differently — follow the label for the exact product you were prescribed.
Is there a generic sulfasalazine?
We do not currently list a generic-labelled sulfasalazine product. That does not always mean none exists — it means none appears under a generic name in the FDA data we track. Ask your pharmacist.
Cite this page
- APA
- pharmaranks. (2026, July 24). Sulfasalazine: uses, dosing, side effects & brands. https://pharmaranks.com/drugs/sulfasalazine
- MLA
- “Sulfasalazine: uses, dosing, side effects & brands.” pharmaranks, 24 July 2026, https://pharmaranks.com/drugs/sulfasalazine.
We summarise public FDA and NIH sources — for a clinical claim, cite the primary source we link to as well.
Sources: FDA openFDA drug label, National Drug Code Directory, and Enforcement (recall) database. This page reproduces public FDA data and is not medical advice. Dosing is set by your prescriber.
Read the full FDA label for sulfasalazine on DailyMed (NIH) ↗.