My vet prescribed Doxylin/Doryx/Vibravet or Doxycycline for my cat.  What does that mean?

Doxycycline is an antibiotic drug, used to treat a variety of illnesses in cats.  It is sold in Australia under the brand names Apex DoxyDoxylin, Doryx and Vibravet, as well as under the drug name Doxycycline.   The different brands offer the same active ingredient in different strengths and different delivery methods (tablet, suspension, paste, etc) and you should check with your vet if you intend to change between the brands.. 


Doxylin is often used by vets to treat cats with upper respiratory infections, sometimes called “kitty colds”, because Doxylin treats a broad spectrum of bacteria.  It can also be used to treat infections of the mouth (including periodontal disease) and urinary tract infections.  Doxycycline can also be used in the treatment of heartworm in cats - it attacks a bacteria found inside heartworms, weakening the heartworm. 


Other brand names for Doxycycline are Apex Doxy, Doxylin, Doryx and Vibravet- whilst these medications contain the same active ingredient, dosages may differ, and you should check with your vet if you intend to change between the brands.


This article answers some of your common questions, such as how Doxycycline helps your cat, the dosage for Doxycycline, and the side-effects of Doxycycline for cats.

How does Doxycycline help my cat?

Doxycycline is a tetracycline antibiotic, which works to prevent bacteria from producing the proteins that the bacteria need to grow and reproduce.  It is very safe, because the protein synthesis is specific to the bacteria, and it has very little effect on animal cells.  The bacteria is inhibited or stopped only whilst they are exposed to the doxycycline, so your vet will discuss with you how long your cat should be taking doxycycline.  


What can I expect when my cat starts on Doxycycline?

  • Doxycycline (Doxylin) works fast, from the very first dose, however it may take a couple of days for you to see that it’s working to treat your cat’s infection.
  • It is important that you periodically discuss your cat’s response to Doxycycline with your vet, who will determine if your cat is responding as expected, and what the ongoing dose of Doxycycline should be.  

How to give Doxylin/Doryx/Vibravet or Doxycycline to my dog?

Doxycycline, Doxylin, Doryx, and Vibravet are available in a number of delivery methods - your vet might prescribe that your cat should take it as a tablet, capsule, or liquid. 


Here’s some handy tips:

  • If administering Doxylin as a liquid, make sure to shake the bottle before measuring the medication carefully
  • If your cat is taking doxycycline as a tablet or capsule, ensure that it is followed by water or food – never give the pill dry. Tablets may be administered whole, crushed or dissolved in some liquid.
  • Vets recommend that you give this medication with food, to limit the risk of upset stomachs. But don't give your cat doxycycline with milk or dairy foods, or antacids - this affects the absorption of the drug, and means it won’t work as well!

Storage of Doxycycline 

The manufacturer of Doxycycline recommends that it be stored at room temperature (below 25 degrees) - though check the storage requirements for the formulation and delivery method that your pet has been prescribed.

Who should NOT take Doxycycline ?

  • Doxycycline should not be given to pregnant or lactating animals 
  • Do not administer doxycycline in combination with milk or dairy products, or antacids as this alters its absorption.
  • Some drugs don’t work as well, if your pet is also taking Doxycycline, and there are drugs that cannot be taken with Doxycycline.  For this reason, please make sure that you tell your vet about all other medications that your dog is taking, including vitamins, supplements and herbal therapies.   

What if I give too much Doxycycline? What if I miss a dose of Doxycycline or give the wrong dose of Doxycycline?
Administration of drug issues

Doxycycline is generally given daily, so there should be 24 hours between doses. If you miss giving a dose of Doxycycline, don’t worry.  If you remember a missed dose, give the dose as soon as possible. However, if it is less than 12 hours until the next dose is due, skip the missed dose, and continue with the regular schedule. Never give your pet two doses at once.

Possible side effects 

Doxycycline is generally well tolerated by cats, although it sometimes causes vomiting, diarrhea, or lack of appetite.  If you are treating your cat using Doxycycline tablets, you must ensure that you don’t “dry pill”, making sure the tablet is washed down (with food or water) so that it doesn’t cause esophageal strictures or upsets.


Doxycycline (Doxylin, Doryx or Vibravet) can also cause sun sensitivity (photosensitivity), particularly on parts of the body not covered in hair.


As with any medication, if you are concerned about a possible side effect of Doxycycline, stop treatment and contact your vet immediately. 

Can I buy Doxycycline (or Doxylin, Doryx or Vibravet) online?

Doxycycline, under any brand name, is a prescription medicine, and you can buy it online from PetScripts once you have a script (prescription) from your vet.  Please ensure that you have read the How to Order page before ordering this item.


This information is not intended nor is it implied to be a substitute for professional medical or veterinary advice or any information contained on or in any product packaging or labels. Always seek the advice of your Veterinarian, Pharmacist, or qualified health provider when starting any new medical treatment, continuing with medical treatment or with any questions you may have regarding your animal's medical condition. Professional advice is required for each particular illness, disease, infection, injury or other medical condition and for dosages of the pharmaceutical product supplied via this website. You take full and total responsibility for what you do with this information and any resulting outcomes from your actions.