Quick answer
Antibiotics for cats are prescription medicines that kill bacteria or stop them from growing. They treat bacterial infections such as abscesses, some bladder infections and secondary infections during cat flu, but they don't work against viruses. Common choices include amoxicillin-clavulanate, doxycycline, clindamycin and a long-acting injection called cefovecin. Your vet chooses the drug and sets the dose for your cat.
Antibiotics for cats are among the most common medicines vets prescribe. They only work against bacteria, so the first job is working out whether bacteria are the problem. This guide explains what antibiotics treat, the types vets use most, what side effects to watch for and why the course matters.
What do antibiotics for cats treat?
An antibiotic is a medicine that kills bacteria or stops them from multiplying. Vets use them for infections such as:
- Bite wounds and abscesses
- Bacterial bladder infections, ideally confirmed with a urine test
- Dental infections
- Secondary bacterial infections in cats with upper respiratory infections
- Skin infections, pneumonia and some other internal infections
A vet needs to examine your cat to decide whether an antibiotic will help. Your vet will choose the drug, set the dose for your cat and tell you how long to give it.
Do antibiotics work for cat flu and other viruses?
No. Antibiotics don’t kill viruses. The AVMA makes the same point for people: colds and flu are viral, so antibiotics won’t help.
Cat flu is usually caused by viruses such as feline herpesvirus and calicivirus. Cornell Feline Health Center notes that antibiotics can be used to control the secondary bacterial infections that commonly occur alongside herpes infection. That’s why your vet may prescribe one for some sneezing cats and not others.
The 2017 international guidelines for vets (ISCAID) advise against antibiotics when nasal discharge is clear and watery, because that usually means an uncomplicated viral infection. Treatment is recommended when thick discharge comes with fever, tiredness or loss of appetite. See our guide to cat sneezing for what to watch at home.
Bladder problems are similar. Cornell reports that the most common diagnosis in cats with urinary signs is idiopathic cystitis, a painful bladder condition with no known cause. It isn’t a bacterial infection, so antibiotics don’t fix it. A urine test helps your vet tell the difference. Read more about cat UTIs.
Which antibiotics do vets use for cats?
Vets pick an antibiotic based on the likely bacteria, where the infection is, how easy the drug is to give and your cat’s health. These are some of the most common.
| Antibiotic | Common brand (US) | Often used for | How it’s given |
|---|---|---|---|
| Amoxicillin-clavulanate | Clavamox | Wounds, abscesses, skin and bladder infections | Tablets or liquid |
| Doxycycline | Many generics | Respiratory infections, including cat flu with a bacterial infection on top | Tablets or capsules |
| Cefovecin | Convenia | Wounds and abscesses | A single injection at the clinic |
| Clindamycin | Antirobe | Deep wounds, abscesses and dental infections | Liquid |
| Fluoroquinolones (such as enrofloxacin) | Baytril | Severe or recurring infections | Tablets or injection |
Amoxicillin for cats
Amoxicillin is a penicillin-type antibiotic. It’s often paired with clavulanate, which helps it work against bacteria that would otherwise break it down. Amoxicillin for cats is approved in this combined form for skin and soft tissue infections and bladder infections. The ISCAID guidelines list amoxicillin as a first-line option for bacterial upper respiratory infections too. Cats with a known penicillin or cephalosporin allergy shouldn’t take it.
Doxycycline for cats
The ISCAID guidelines call doxycycline the first-line choice for suspected bacterial upper respiratory infections in cats, because cats tolerate it well and it works against the usual bacteria involved. It has one well-known risk. Tablets and capsules can stick in a cat’s food pipe (esophagus) and cause inflammation and scarring, which makes swallowing hard. A 2005 report of four cats with this problem advised following oral medicine with water or food. Ask your vet whether a liquid form is an option for your cat. Our guide on how to give a cat a pill covers the safest technique.
Cefovecin injection
Cefovecin (Convenia) is a long-acting injection your vet gives once in the clinic. It’s approved for skin infections such as wounds and abscesses in cats, and it helps cats that are hard to pill. The downside is that it can’t be stopped once given. The label notes it may stay in the body for up to 65 days, so any reaction may take longer to settle.
Clindamycin
Clindamycin is approved for cats with skin infections, deep wounds, abscesses and dental infections. Its label lists vomiting and diarrhea as the side effects occasionally seen.
Fluoroquinolones and the eye warning
A 2002 review in JAVMA advised that fluoroquinolones such as enrofloxacin be reserved for severe or recurring infections, ideally chosen based on a culture. Enrofloxacin carries a specific warning for cats. Its label says that, in rare instances, use in cats has been linked to damage to the retina, the light-sensing layer at the back of the eye.
In a 2001 study of 17 affected cats, the most common signs were widely dilated pupils and sudden blindness. Some cats regained vision, but many did not. The label notes dilated pupils may be an early warning sign. If your cat is on enrofloxacin and you notice big pupils or bumping into things, call your vet the same day.
What are the side effects of antibiotics for cats?
Side effects depend on the drug. The labels for common cat antibiotics list vomiting, diarrhea, poor appetite and tiredness among the most frequent.
| Effect | What it looks like | What to do |
|---|---|---|
| Upset stomach | Drooling, lip-licking, vomiting after a dose | Ask your vet if the dose can be given with food |
| Diarrhea | Loose or more frequent stool | Monitor Call your vet if it’s severe, bloody or lasts |
| Poor appetite or tiredness | Eats less, sleeps more | See vet soon Call your vet if your cat stops eating |
| Trouble swallowing | Regurgitating, gulping, drooling during a pill course | See vet soon Call your vet the same day |
| Allergic reaction | Facial swelling, hives, trouble breathing | Emergency Go to a vet now |
| Vision changes | Wide pupils, bumping into things | Emergency Call your vet now |
If your cat vomits or has diarrhea on antibiotics, don’t stop the medicine on your own. Your vet may switch the drug or suggest giving it with a meal.
Why should my cat finish the course?
The AVMA advises giving antimicrobials exactly as directed: the right doses, at the right times, for the right number of days. That means not skipping doses and not stopping early just because your cat looks better. If your vet changes the plan, follow the new plan.
This matters because of antibiotic resistance. According to the AVMA, a course of treatment rarely kills every single bacterium. The few survivors can include ones that resist the drug, and they can pass that ability on. Resistant infections are harder to treat, for your cat and for other animals and people.
You can help by:
- Not asking for antibiotics your vet doesn’t think are needed
- Letting your vet run a culture when they suggest one
- Not saving antibiotics for later use
Can I give my cat leftover or human antibiotics?
No. The AVMA advises against saving antibiotics for later or using ones prescribed for someone else. A leftover pill may be the wrong drug for the new infection, the wrong strength or past its date.
Human antibiotics are a bigger risk. The dose, the form and even the choice of drug are different for cats, and some antibiotics, like enrofloxacin, need careful dosing in cats to avoid side effects. Many human medicines are dangerous to cats, as our guide to human medications toxic to cats explains. Only give your cat antibiotics your vet prescribed for that cat.
When should I call the vet about antibiotics?
Call during office hours if your cat isn’t improving after a few days, gets worse, or you’re struggling to give the medicine. Your vet may be able to switch to a liquid or a one-time injection. For signs in the red box at the top of this page, or after hours, see our cat emergency guide.
For other medicines your vet may prescribe, including maropitant for vomiting, browse our cat medications guides.
Frequently asked questions
Can I give my cat antibiotics left over from a previous illness?
No. The drug, strength and length of treatment are chosen for one infection in one cat. Leftovers may be the wrong medicine, the wrong amount or out of date. The AVMA advises against saving antibiotics for later or using ones prescribed for someone else.
Will antibiotics cure my cat's cold?
Not on their own. Cat flu is usually caused by viruses, and antibiotics don't kill viruses. Vets use them when there are signs of a bacterial infection on top, such as thick yellow or green discharge with fever, tiredness or poor appetite.
Why does my vet want to run a urine culture before giving antibiotics?
Many cats with bladder signs don't have a bacterial infection at all. A culture shows whether bacteria are present and which antibiotic will work, so your cat gets the right drug only when it's needed.
What should I do if my cat gets diarrhea on antibiotics?
Mild, short-lived loose stool can happen. Call your vet if it's severe, has blood in it, lasts more than a day or two, or your cat stops eating. Don't stop the course without asking, and don't give human anti-diarrhea medicine.
Sources
- Lappin MR et al. Antimicrobial use guidelines for treatment of respiratory tract disease in dogs and cats (ISCAID). J Vet Intern Med, 2017
- AVMA: Antimicrobial use and resistance, FAQs for pet owners
- Cornell Feline Health Center: Respiratory Infections
- Cornell Feline Health Center: Feline Lower Urinary Tract Disease
- Gelatt KN et al. Enrofloxacin-associated retinal degeneration in cats. Vet Ophthalmol, 2001
- Wiebe V, Hamilton P. Fluoroquinolone-induced retinal degeneration in cats. JAVMA, 2002
- German AJ et al. Oesophageal strictures in cats associated with doxycycline therapy. J Feline Med Surg, 2005
- FDA-approved label (DailyMed): Convenia (cefovecin sodium) injection
- FDA-approved label (DailyMed): Baytril (enrofloxacin) tablets
- FDA-approved label (DailyMed): Clavamox (amoxicillin and clavulanate potassium) chewable tablets
- FDA-approved label (DailyMed): Antirobe Aquadrops (clindamycin hydrochloride)
Written by the CatsMed Team from the sources above. Reviewed by Dr. Jarod Grantland, DVM. It isn’t a substitute for seeing a vet. See how we research.
The CatsMed Team researches and writes every guide and tool on the site. We work from the references vets use: the Cornell Feline Health Center, the American Association of Feline Practitioners (AAFP), International Cat Care (iCatCare), the Merck Veterinary Manual, ASPCA Animal Poison Control and peer-reviewed studies. Every page lists its sources, and we update pages when guidance changes.
Not every guide has been reviewed by a veterinarian: the ones that have say so at the bottom and name the reviewer. None of them replaces a vet. If your cat is unwell, call your vet.
Dr. Jarod Grantland, DVMVeterinary reviewerDr. Jarod Grantland earned his Doctor of Veterinary Medicine from the Auburn University College of Veterinary Medicine in 2009. Since 2014 he has run Athens Animal Hospital in Athens, Alabama, caring for companion animals and livestock.
He reviews selected CatsMed guides. A guide shows his name only after he has approved that exact version of the text, and it goes back to unreviewed if the text changes.
