Stomach & digestion Dogs

Sulfasalazine for dogs

Treats inflammation of the large bowel (colitis) and vasculitis. [1]

Last reviewed: October 2026 · 2 sources · see sources

Quick answerSulfasalazine is a prescription medicine for dogs. It releases an anti-inflammatory compound directly in the colon. The most common side effects: low appetite and vomiting.

Key facts

Generic nameSulfasalazine
Common brand namesAzulfidine
Used inDogs
TypeStomach & digestion
Prescription?Prescription
Typical US priceNot listed (no reliable public source)

What it's used for

Treats inflammation of the large bowel (colitis) and vasculitis. [1]

How it works

It releases an anti-inflammatory compound directly in the colon. [1]

Side effects and cautions

Common side effects: Low appetite and vomiting. Dry eye is a serious possible effect. [1]

Use with care: Not for pets with dry eye or sulfa allergy. Your vet may check tear production. [1]

Call your vet right away if your pet has trouble breathing, facial swelling, hives, collapse, or any side effect that is severe or getting worse.

About dosingDosing is your vet's call. We don't list doses because the right amount depends on your pet's weight, age, health and other medicines. Don't change a dose or stop a medicine without asking your vet, and never give a pet medicine meant for people unless your vet tells you to [2].

What it costs

We don't list a price for this one because we couldn't find a reliable public source. Ask your vet or pharmacy for a quote; prices depend on your pet's size, the dose and where you fill it.

Sulfasalazine FAQ

What is Sulfasalazine used for in dogs?

Treats inflammation of the large bowel (colitis) and vasculitis.

What are the side effects of Sulfasalazine?

Low appetite and vomiting. Dry eye is a serious possible effect.

Does Sulfasalazine need a prescription?

Yes. It needs a prescription from a veterinarian.

How much Sulfasalazine should I give my pet?

Only your veterinarian can tell you. The right dose depends on your pet's weight, health and other medicines, so we don't list doses. Never give a pet a medicine prescribed for a person or another animal without asking your vet.

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This page is general information for pet owners, not veterinary advice. Talk to your vet about your own pet.

Sources (2) — tap to show
  1. VCA Animal Hospitals – Sulfasalazine (veterinary drug handout)
  2. FDA – Frequently asked questions about animal drugs