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Sulfasalazine by Watson Labs

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General Description:

Sulfasalazine is a combination of a sulfa antibiotic and a salt of salicylic acid (aspirin). It is used in dogs and cats to treat colitis or bowel inflammation. Give this medication with food. Sulfasalazine is available as an oral suspension or as tablets.

What is this drug?
• An anti-inflammatory; a combination of a sulfa antibiotic and a salt of salicylic acid (aspirin)
• Given by mouth

Reasons for prescribing:
• Colitis or bowel inflammation (bloody or mucous diarrhea with urgency and occasionally, vomiting)

What dogs/cats should not take this medication?
• Cats are sensitive to salicylates. Dose adjustments will be made to compensate.
• Pets known to have had an allergic reaction to the sulfasalazine, salicylates (aspirin), or other sulfa drugs
• Dehydrated animals (as kidney stone formation may occur)
• Anemic patients, or those who have been anemic in the past
• Pets with liver or kidney disease
• Use with caution in breeds pre-disposed to 'dry-eye'
• Use with caution in breeding male dogs; may affect fertility
• Pregnant or nursing animals


For liquids, shake well before accurately measuring the dose.

Give this medication with food.

Give medication as directed by your veterinarian. Dogs usually receive sulfasalazine two or three times daily . Cats usually receive it once a day.

The dose may be gradually increased until the diarrhea resolves, and then decreased gradually when bowel movements are normal.

Give the exact amount prescribed and only as often as directed. Missed doses reduce the effectiveness of therapy.

Sulfasalazine is a brightly-colored medication. If your pet vomits, the orange dye is not easily removed from carpeting/fabrics.

Ensure your pet has fresh, clean drinking water at all times.

Ideally, give the medication at the same time daily.

What if dose is missed?

If a dose is missed, give it as soon as you can. If it is time already for the next dose, skip the missed dose and go back to the normal schedule. Do not give two doses at the same time.

What to tell/ask veterinarian before giving medication?

Talk to your veterinarian about:
• When will your pet need to be rechecked
• What tests may need to be performed prior to and during treatment with this drug
• Risks and benefits of using this drug

Tell your veterinarian about:
• If your pet has experienced side-effects on other drugs/products
• If your pet has experienced digestive upset now or ever
• If your pet has experienced liver or kidney disease now or ever
• If your pet has experienced any other medical problems or allergies now or ever
• All medicines and supplements that you are giving your pet or plan to give your pet, including those you can get without a prescription. Your veterinarian may want to check that all of your pet's medicines can be given together.
• If your pet is pregnant or nursing or if you plan to breed your pet

Storage and Warnings:

Store sulfasalazine in a tight, light resistant, childproof container in a cool, dry place at room temperature away from heat and direct sunlight.

Keep this and all medication out of reach of children and pets. Call your physician immediately if you accidentally take this product.

Pet owners allergic to sulfa drugs and/or aspirin-like should use caution when handling this drug.

Potential side effects:
• Allergic reaction (difficulty breathing, closing of throat, hives, swollen lips, tongue or face; or fever, abdominal pain, cramping, bloody diarrhea; or sore throat, fever or yellow eyes). Stop the medication and seek veterinary medical attention immediately.
• The only likely side effect is decreased tear production. Watch for eye discomfort (squinting, redness, blinking, eye rubbing, increased discharge). This usually only occurs with long-term therapy.

Other side-effects noted with sulfa drug administration are:
• Decreased appetite and vomiting (cats)
• Joint inflammation (arthritis, fever, muscle soreness)
• Skin rashes and itchiness
• Liver failure (nausea; yellowing of gums, skin, eyes)
• Kidney failure (increase thirst and urination)
• Blood abnormalities (bleeding tendencies, pale gums, fatigue, or fever of 103-105° F)

It is important to stop therapy and contact your veterinarian immediately if you think you pet has a medical problem or side effect from this product's therapy.

Can this drug be given with other drugs?
• Yes, but possible interactions may occur with antacids, aspirin, digoxin, folic acid/methotrexate (a cancer chemotherapeutic), phenylbutazone, phenytoin, probenecid, thiazide diuretics and warfarin (an anticoagulant).
• If your pet experiences any unusual reactions when taking multiple medications, contact your veterinarian


Contact your veterinarian immediately if pet eats more than the prescribed amount.

What else should I know?

Notify your veterinarian if your animal's condition does not improve or worsens despite this treatment.

As with all prescribed medicines, sulfasalazine should only be given to the dog/cat for which it was prescribed. It should be given only for the condition for which it was prescribed.

This is just a summary of information about sulfasalazine. If you have any questions or concerns about sulfasalazine or for the condition it was prescribed, contact your veterinarian.


Common Drug Name

Common Brand Names
Generic products are available

Store at room temperature in a tight, light resistant, childproof container.

Sulfasalazine is used to treat inflammation of the bowel in dogs, cats, and ferrets.

Dose and Administration
Your veterinarian may gradually increase the dose until the stools are normal; then, the dose may be decreased. Always follow the dosage instructions provided by your veterinarian.  If you have difficulty giving the medication, contact your veterinarian.
Give by mouth. This medication should be given with food, unless directed otherwise by your veterinarian.
If you miss a dose, give it as soon as you remember. If it is almost time for the next dose, skip the one you missed and go back to the regular schedule. Do not give 2 doses at once.
This medication should only be given to the pet for whom it was prescribed.

Possible Side Effects
Keratoconjunctivitis sicca (KCS, dry eye) may occur with long-term use of sulfasalazine.
Stop giving the medication and consult your veterinarian if your pet experiences discharge from the eye, redness of the eye, squinting, or other signs related to the eye.
Cats may have vomiting or a loss of appetite.
Other less common side effects include anemia resulting in pale gums and tiredness; low platelets resulting in bleeding tendencies; fever; kidney damage resulting in increased thirst and urination; and skin rashes and itchiness. Side effects involving the liver also include jaundice (yellowing of the gums, skin, or eyes). Stop giving the medication and consult your veterinarian if your pet experiences any of these signs.
If your pet experiences an allergic reaction to the medication, signs may include facial swelling, hives, scratching, sudden onset of diarrhea, vomiting, shock, seizures, pale gums, cold limbs, or coma. If you observe any of these signs, contact your veterinarian immediately.

Not for use in animals who are hypersensitive (allergic) to it, other sulfa medications, or aspirin.
Use with extreme caution in pregnant or lactating animals (female animals nursing their young). May decrease fertility in male dogs.
Do not use in animals with blood cell abnormalities such as anemia.
Not for use in animals with dehydration, intestinal obstruction, urinary obstruction, liver disease, bladder or kidney stones, or kidney disease.
The pet should be encouraged to drink water to prevent urinary stone formation.
Consult with your veterinarian regarding the physical examinations and laboratory testing necessary prior to and during treatment with sulfasalazine.

Drug, Food, and Test  Interactions
Consult your veterinarian before using sulfasalazine with other medications, including vitamins and supplements, methotrexate, warfarin, phenylbutazone, thiazide diuretics, salicylates (aspirin), probenecid, phenytoin, folic acid, digoxin, and antacids since interactions may occur.
No known food interactions.

Signs of Toxicity/Overdose
Signs of toxicity or overdose are similar to the side effects listed above, and may also include depression, increased rate of breathing, muscle weakness, confusion, seizures, and facial swelling. If you know or suspect your pet has had an overdose, or if you observe any of these signs in your pet, contact your veterinarian immediately.
Keep this and all other medications out of the reach of children and pets.

This information may not cover all possible uses, directions, side effects, precautions, allergic reactions, drug interactions, or withdrawal times. Always consult your own veterinarian for specific advice concerning the treatment of your pet.


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