Amoxicillin for Pets
Amoxicillin is a prescription aminopenicillin antibiotic used in dogs and cats to treat certain bacterial infections. It should only be given under veterinary guidance, because the right antibiotic depends on the type of infection and the bacteria involved.
Amoxicillin at a Glance
Drug class
Aminopenicillin antibiotic in the beta-lactam family.
Common brand names
Amoxil, Amoxi-Tabs, Amoxi-Drops, Bimox, Novamoxin.
Common forms
Tablet, capsule, oral liquid suspension, and some injectable formulations used in veterinary settings.
Used in
Dogs and cats under veterinary supervision; use in cats is commonly extra-label.
What Amoxicillin Is Used For
Amoxicillin is an antibiotic used to treat susceptible bacterial infections in pets. Veterinary sources describe it as a broad-spectrum aminopenicillin that works by interfering with bacterial cell wall formation, which helps kill certain bacteria. In dogs and cats, veterinarians may prescribe it for skin and soft tissue infections, wound or abscess infections, some urinary tract infections, some respiratory infections, and certain gastrointestinal bacterial infections when amoxicillin is an appropriate choice. It does not treat viral infections, and it is not effective against all bacteria, especially those that produce beta-lactamase unless a protected combination such as amoxicillin-clavulanate is chosen by a veterinarian.
Side Effects to Watch For
Many pets tolerate amoxicillin well, but side effects can happen.
- Common side effects: decreased appetite, vomiting, diarrhea, or other mild stomach upset.
- Possible allergic reaction: rash, facial swelling, fever, hives, or trouble breathing.
- Cats may need more prompt attention for prolonged loss of appetite.
- Rare or concerning signs: incoordination, marked lethargy, or symptoms that worsen instead of improving.
- Drug sensitivities can appear even after earlier doses seemed fine, so monitor for changes during the full treatment course.
Dosing & Administration
Always follow your vet's instructions exactly. Do not change the dose, frequency, or duration on your own, and do not use leftover antibiotics or a human prescription unless your veterinarian specifically told you to. Amoxicillin is commonly given by mouth as a tablet, capsule, or liquid. It may be given with or without food, but giving it with a small meal may help if your pet gets stomach upset. Finish the medication for as long as your veterinarian prescribed, even if your pet seems better sooner, unless your veterinarian tells you to stop. If you miss a dose, give it when you remember unless it is almost time for the next dose; in that case, skip the missed dose and return to the regular schedule. Do not give two doses at once. Tell your veterinarian about any other medications, supplements, or known penicillin or cephalosporin allergies before starting treatment.
When to Call a Vet
Go to the ER now
- ● Difficulty breathing, facial swelling, collapse, or other signs of an allergic reaction.
- ● Suspected overdose.
- ● Severe vomiting, severe diarrhea, or sudden weakness after a dose.
See a vet within 24 hours
- ● Side effects that persist or get worse, including ongoing vomiting or diarrhea.
- ● Your cat stops eating or has prolonged loss of appetite.
- ● Your pet seems uncoordinated, unusually lethargic, or develops a rash.
Watch at home, call if it worsens
- ● Mild temporary stomach upset after starting the medication.
- ● Slight decrease in appetite that resolves quickly and does not progress.
- ● No immediate visible improvement in the first day or two, since antibiotics may need time while the infection responds.
Common Questions About Amoxicillin
Can I give my dog human amoxicillin?
What happens if I miss a dose?
Can my cat take amoxicillin?
How long does amoxicillin take to work?
Can I stop amoxicillin when my pet seems better?
Disclaimer: The information provided in this article is for educational purposes only and does not constitute veterinary medical advice. Reading this content does not establish a veterinarian-client-patient relationship. Every pet is different — always consult a licensed veterinarian before making decisions about your pet's health, diet, or care. If you'd like personalized guidance, you can talk to one of our vets. If your pet is experiencing a medical emergency, contact your local emergency animal hospital immediately.