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Sulfasalazine for Dogs & Cats: IBD, Colitis & Gut Inflammation

Published on September 10, 2024
Updated on November 5, 2025
Reviewed by Petco's Veterinarian Team
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Sulfasalazine is a medication used in dogs and cats to decrease inflammation in the gastrointestinal tract.

Summary

Used For:

Inflammation of the bowel in dogs, cats and other pets

Brands:

Azulfidine

Species:

Dogs and cats

Other names:

Drug type:

Anti-inflammatory and antibiotic properties

Prescription required:

Yes

Pregnancy and lactation:

Not safe for use in pregnant or lactating animals.

Side effects:

Depression, GI upset, pale gums, bleeding tendencies, fever, jaundice

General description

Sulfasalazine is used to treat inflammation of the bowel in dogs, cats and other pets. It can also be used in combination with other medications to treat susceptible infections in animals.

Buy Sulfasalazine now on Petco. A prescription from your veterinarian is needed to purchase.

Uses

Inflammation of the gastrointestinal tract

How it works

Sulfasalazine reduces the number of chemicals produced in the body that create inflammation.

Dosage

Dogs: 15-30 milligrams per kilogram of body weight given orally every 8-12 hours not to exceed a daily dose of 6 grams.

Forms

500 milligram tablets are available

Storage information & handling

Tablets: keep dry and out of direct sunlight.

What results can I expect?

Animals with gastrointestinal inflammation should have some relief after the first dose is given; it may take several days to weeks to achieve full resolution of symptoms.

Missed Dosage

A missed dose should be given as soon as possible, but do not give your pet two doses at the same time.

Overdose / acute toxicity

Side effects will be more severe with an overdose.

Side effects

May include:

  • Depression
  • Vomiting
  • Loss of appetite
  • Pale gums
  • Tiredness
  • Bleeding tendencies
  • Fever
  • Increased thirst or urination
  • Skin rashes
  • Itchiness
  • Jaundice (yellowing of the gums, skin or whites of the eyes)
  • Increased rate of breathing
  • Weakness
  • Confusion
  • Seizures
  • Facial swelling

Contraindications

*Do not use in animals with liver disease or a known hypersensitivity.

*Do not use in pregnant animals.

Drug interactions

Sulfasalazine should not used in combination with warfarin, dapsone, etodolac or folic acid. Use in conjunction with other NSAIDs has increased risk of bleeding and other side effects.

Precaution

Keratoconjunctivitis sicca (KCS, dry eye) may occur with long-term use of sulfasalazine, especially in dogs. Stop giving the medication and consult your veterinarian if your pet experiences discharge from the eye, redness of the eye, squinting or other eye conditions.

Sources

Saunders Handbook of Veterinary Drugs

Disclaimer
The information contained on this page is for educational purposes only. This medication should only be given under the advice of a veterinarian who has examined your pet under the laws applicable to your state of residence.

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