Amoxicillin for Cats

Written By Leslie Ingraham
Published: 06/25/2021Updated: 06/25/2021
Amoxicillin for Cats

Amoxicillin is one of the many penicillins available for the treatment of many types of bacteria.It is useful against several groups of gram-positive and gram-negative bacteria, including Salmonella and Clostridium, (which cause food poisoning), Staphylococcus and Streptococcus infections and other bacterial illnesses. Amoxicillin is the first choice of veterinarians treating urinary tract infections in cats. It may also be effective for the treatment of diarrhea in cats and kittens, as well as infected wounds of the skin. It is not used to treat viral infections.


Amoxicillin for cats is available in tablets, capsules and as a liquid suspension. Injectable amoxicillin is only available at the veterinary hospital. The cost may vary depending on which formulation and dosage has been prescribed and where it is obtained. Tablets and capsules average from about $ .40 apiece online to $3.00 apiece at the veterinary clinic. A 15 ml bottle of an Amoxicillin suspension costs an average of $23. In-hospital injections cost around $30. 


Amoxicillin for cats can be given by mouth or as an injection by a veterinarian. Chewable tablets are available at the same strengths (50 to 500 mg) as the tablets and capsules. However, the chewable tablets may contain another chemical that may help make the amoxicillin more effective, and your cat’s veterinarian may not want to start with this form. An average dose is as follows:

Dosage instructions

It’s important to give amoxicillin to your cat at the dosage prescribed and for a full 10 days to 2 weeks as prescribed by your veterinarian. Even if your cat seems to feel better, don’t stop the medication or the infection may not resolve. It can be given with or without food but if it seems to upset their stomach, switch over to giving it with meals or other food.

Amoxicillin tablets or capsules may be given inside treats or food to encourage your cat to take it. The suspension may be the easiest way to give amoxicillin, but it is common for them to spit out some of the liquid. In this case do not give them more, just resume the original dosing schedule.


According to the Merck Veterinary Manual, amoxicillin is more effective in treating feline urinary tract infections than other antibiotics, including Penicillin G. It is readily absorbed by the GI tract and rises to therapeutic levels within the urinary tract in a short time. 

In a study of 122 cats with infected skin wounds or abscesses, amoxicillin was evaluated for its efficacy in these types of cases, utilizing amoxicillin oral paste and suspension. It was found that in 95.1% of the tested cats, the infection was resolved and bacteria were eliminated. For the 5% whose infection was not totally resolved at 10 days, another course of amoxicillin proved to be effective. 

Amoxicillin has also been shown to be an effective treatment in a variety of other conditions, including food poisoning.

Side effects of amoxicillin in cats

The most common side effects noted in cats receiving amoxicillin for infection are gastrointestinal in nature, including:

This medication wears off 24 hours after the last administration, at which point the side effects should gradually disappear. In the meantime, the side effects of amoxicillin can be treated by preparing foods for your cat that are tempting and can help alleviate some of the GI symptoms, such as chicken and white rice.


Amoxicillin should not be used in cats with risk factors such as allergies to penicillins or other antibiotics. Other factors that require caution when using amoxicillin for cats include pregnancy and lactation, diabetes and chronic kidney disease.

Drug interactions

Amoxicillin for cats (Amoxil, Amoxi Tabs, Amoxi-Drops, Bimox, Moxatag, Novamoxin) may negatively interact with the following medications:

  • Bacteriostatic antimicrobials (tetracyclines, sulfonamides, spectinomycin, trimethoprim, chloramphenicol, macrolides, lincosamides)
  • Blood thinners (warfarin)
  • Anti-rheumatics (methotrexate)
  • Anti-gout medication (probenecid)

Before beginning treatment with amoxicillin, be sure to talk to your veterinarian about any other medications or supplements your cat is taking, including fish oils and vitamins. 

Allergic reactions to amoxicillin

Some cats may exhibit signs of an allergy to amoxicillin, characterized by skin rash, fever, swelling, incoordination, increased heart rate and breathing issues. The severity of the allergic reaction may be different in individual cats, but the symptoms will not change. A quick call to the veterinarian may result in a prescription for anti-allergy medication and/or a visit to the clinic.

Frequently asked questions

Do I need a prescription for amoxicillin for cats?

Amoxicillin may only be obtained with a prescription from your veterinarian. Because amoxicillin is used so frequently in pets, some veterinary clinics keep a supply of the drug and dispense it directly from there. 

What do I do if I skip a dose?

If you miss a dose, give it as soon as you remember, but if it’s close to the time for the next dose, skip the dose and resume the schedule with the next dose. Never administer two doses at once, or give your cat extra doses.

How do I store amoxicillin?

Amoxicillin tablets or capsules should be stored at room temperature between 59℉ and 86℉ in a dry place. The liquid suspension may be stored in the refrigerator, but this is not strictly required, and cats typically accept liquid medication more readily when it is at room temperature. If amoxicillin suspension has been stored in the refrigerator, warm the syringe in your hand or a bowl of warm water before approaching with the medication. Keep children and pets away from the medication.

What do I do in case of an emergency?

If you suspect an overdose or other problem, contact your veterinarian immediately or take your cat to an emergency veterinary clinic. Symptoms of a drug overdose can include vomiting or drooling, disorientation, agitation, changes in heart and breathing rates, and lethargy.

Is there specific monitoring that should be done with this medication?

While there is no specific monitoring that needs to be done with amoxicillin, your veterinarian will likely want to see your cat during or after treatment to check on the status of the infection.

Need pet insurance?
Need pet insurance?

Learn more in the Wag! app

Five starsFive starsFive starsFive starsFive stars

43k+ reviews


© 2023 Wag Labs, Inc. All rights reserved.