Terramycin for Cats

Written By Leslie Ingraham
Published: 07/14/2021Updated: 07/15/2021
Terramycin for Cats

Terramycin for cats is an ophthalmic ointment containing oxytetracycline and Polymyxin B sulfate. Oxytetracycline and Polymyxin B sulfate are strong antibiotics.The synergistic combination of these broad-spectrum antibiotics is effective against gram-positive and gram-negative bacteria found in superficial infections of the eye, including conjunctivitis, blepharitis (infection in the eyelids), keratitis (inflammation of the cornea), and corneal ulcers. 


Terramycin for cats is only available with a prescription, and may be directly supplied by your veterinarian. The average retail cost of Terramycin is between $19 and $22. The cost at a veterinary hospital will likely be slightly higher. 


Terramycin for cats is dispensed in tubes containing bright yellow ointment that is put into the cat’s affected eyes. The usual dose is:

Dosage Instructions

Wash your hands before and after the application to prevent contamination. Be sure not to touch the tip of the applicator with your fingers or to the surface of the cat’s eye. If you’re unable to keep the cat still, it helps to wrap a towel around them with just their head out to restrain and calm them, and prevent accidental injury to their eyes. It may also help to hold the cat on your lap or have someone else hold them. Once your cat has settled down, you can safely apply the ointment.

Pull the eyelid downward and apply a thin strip of ointment to the lower eyelid sac. The cat will blink, spreading the ointment over the eye.They will likely paw at their eye a little. Distraction with a treat or toy may help reduce pawing. Be sure not to skip any doses or stop the medication before the time your veterinarian prescribed. To do so may allow the infection to re-blossom, requiring longer treatment.


Terramycin for cats is effective against primary or secondary gram-positive and gram-negative bacterial infections. It is also effective against Pseudomonas aeruginosa, Chlamydia and Mycoplasma conjunctivitis, an inflammation of the pink tissue surrounding the eye.

Terramycin for cats is not effective against viral infections such as herpes. If herpes is suspected, the veterinarian will treat the cat with antiviral agents. Sometimes viral infections can cause secondary bacterial infections, and antibiotics will be administered with the antiviral medication.

Side Effects of Terramycin for Cats

Side effects with ophthalmic Terramycin for cats are rare, but they may include:

  • Blurry vision, which can include walking into things
  • Lid swelling
  • Evidence of stinging or itching, such as pawing at the eye or rubbing the face against upholstered furniture or rugs

Drug Interactions

There is always the possibility that combined antibiotics may cause antibiotic resistance causing them to stop working as well as they should. While it is possible this event can occur with oxytetracycline and other antibiotics, there is no specific warning about this with Terramycin for cats. However, one drug interaction mentioned in the literature is with:

Since this immunosuppressant is used primarily after human kidney transplants to prevent rejection, this drug reaction is rarely, if ever, seen in a cat.

Allergic Reaction and Sensitivity

Terramycin ointment should not be given if a cat has an allergy to oxytetracycline or Polymyxin. Physical symptoms of an allergy to Terramycin ophthalmic ointment are lid swelling and itching that causes the cat to paw at their eyes.

In rare cases, high sensitivity to Terramycin will cause an anaphylactic reaction, typically within 4 hours of administration. Signs of anaphylaxis in cats include wheezing, difficulty breathing, swelling of the face, weakness, and vomiting. A cat in anaphylactic shock is an emergency situation and needs to be seen by a veterinary professional immediately. In a study of 61 cats who suffered anaphylaxis, 21% had received Terramycin; the percentage of those who survived with treatment was 82%.

Frequently asked questions

How do I store Terramycin?

Terramycin should ideally be stored at a room temperature between 59 and 77 degrees. It will also be safe to use if kept between 59 to 86 degrees for short times. Refrigeration is unnecessary.

How long will I have to give my cat Terramycin ointment?

Symptoms of conjunctivitis or other bacterial infection should begin to disappear almost immediately after starting the ointment. Continue to apply the drug to the cat’s eye(s) 2 to 4 times a day for 2 to 3 weeks as directed by your veterinarian. Do not stop the medication even if the infection seems to be clearing as this might cause it to return.

What do I do if I skip a dose?

If you skip a dose, administer it as soon as you can. If the redosing time is close to the time for the next scheduled application, hold off and get the cat back on track with the original schedule. 

Is it possible to give an overdose of Terramycin to my cat?

There are no known warnings of Terramycin overdose. However, the medication should be used exactly as the veterinarian has prescribed to ensure success.

Need pet insurance?
Need pet insurance?

Learn more in the Wag! app

Five starsFive starsFive starsFive starsFive stars

43k+ reviews


© 2024 Wag Labs, Inc. All rights reserved.

© 2024 Wag Labs, Inc. All rights reserved.