Major Uses

Trimethoprim with sulfadiazine is an antibiotic that is commonly used to kill many different kinds of bacteria, as well as some intracellular parasites, and the microorganism that causes toxoplasmosis.

Common Precautions

Animals with liver impairment or blood disorders should avoid using trimethoprim with sulfadiazine. Pregnant animals should also not use this drug, as it may damage the fetus. If treatment continues on for too long, patients may suffer from hypothyroidism. Trimethoprim with sulfadiazine may interfere with other drugs, so a veterinarian should be advised of all medications an animal is taking.

Some negative side effects that are associated with trimethoprim with sulfadiazine include dry eye, vomiting, lack of appetite, liver inflammation, diarrhea, facial swelling, fever, arthritis, and blood disorders such as hemolytic anemia and low platelet counts.

Trimethoprim with sulfadiazine should not be used in animals with a known allergy or hypersensitivity to the drug. A veterinarian should be contacted immediately if an overdose is suspected, the symptoms of which can be nausea, diarrhea, confusion, depression, facial swelling, and bone marrow disease. Other possible symptoms of an overdose include anemia caused pale gums, bleeding tendencies, and tiredness.


Trimethoprim with sulfadiazine should be kept at room temperature and stored in a childproof container that is tightly sealed. It should carefully be kept out of the reach of children and pets.


A typical dose of trimethoprim with sulfadiazine is 15-30 mg/kg one to three times a day. Doses may be lower depending on the potential length of treatment. Treatment should continue for the full length specified by a veterinarian, even if the patient seems better. Should a dose be forgotten, it should be administered as soon as possible. If it is almost time for the next dose, the missed dose should be skipped and the regularly scheduled dose should be given. Two doses of Trimethoprim with sulfadiazine should not be administered at the same time.

Doses may vary in different species, when the drug is given by a different route or concurrently with other medications, and with regards to a patient's age, breed, and health status. A veterinarian's dosing instructions and/or those printed on the medication label should be followed closely.

This information is for general reference only and should not be used for the diagnosis or treatment of any condition of your pet. It's intended as a general reference, this information may not include all possible uses, precautions, directions, reactions (including allergic), drug interactions, or withdrawal times. Always consult your local veterinarian and have your pet examined for any advice concerning the diagnosis and treatment of your pet, including which products and doses are most appropriate. Any trademarks are the property of their respective owners. VetDepot is not a pharmacy. All prescription products are dispensed by our Pharmacy Partner. Article last updated 2/2014.