Amoxicillin is a penicillin antibiotic for use in dogs. In technical jargon it works by disrupting cell wall synthesis in susceptible forms of bacteria, leaving them unstable and unable to survive. The drug is very similar to ampicillin but has the advantage of being more readily absorbed by the body.

Beta Lactamase Producing Bacteria: This medicine is unable to treat bacterial infections if the bacteria produces beta lactamase. To treat infections caused by beta lactamase producing bacteria you could try Clavamox®, a combination medicine containing amoxicillin and clavulanic acid. Do not use without veterinary permission.

Recommended Dosage

Do not give this medicine to your dog without first visiting the vet for a diagnosis, prescription, and treatment plan.


Give 5 mg/lb body weight twice daily for 5 to 7 days or for 48 hours after symptoms subside.

Weight of Dog (lbs)

Amoxi-Tabs Tablets to Use

101 x 50 mg
15½ x 150 mg
201 x 100 mg
301 x 150 mg
401 x 200 mg
602 x 150 mg
801 x 400 mg
> 80Appropriate combination.


Amoxicillin liquid suspensionAmoxi-Drop is available as a 15 mL or 30 mL bottle. For correct reconstitution 12 mL of water should be added to the 15 mL bottle, and 23 mL of water should be added to the 30 mL bottle. If this guide is followed, every milliliter of reconstituted Amoxi-Drop solution will contain 50 milligrams of active ingredient. You should then administer 0.1 mL for every pound of body weight.

Administer this dose twice daily for 5 to 7 days or for at least 48 hours after symptoms subside.

Important: Keep the solution refrigerated and discard after 14 days.

Example: A 20 pound dog would be given either one 100 mg Amoxi-Tabs tablet or 2 mL of reconstituted Amoxi-Drop solution per dose.

Is It Safe?

Because this medicine is a penicillin the main concern is usually the possibility of an allergy. Allergic reactions to penicillin can be very dangerous. Do not give it to a dog who has suffered an allergic reaction to penicillin antibiotics or penicillin derivatives (such as ampicillin) in the past. Also, because of possible cross-reactivity it is best to avoid use in dogs who have suffered bad reactions to other beta-lactam antibiotics such as cephalexin.

In severely debilitated dogs it should be injected intravenously to ensure the drug is absorbed properly.

Pregnancy/Nursing: This drug crosses the placenta and passes through milk. Even though no adverse effects have been demonstrated we recommend avoiding use in pregnant and nursing dogs whenever possible.

Usage Guidelines

Consult with your vet before use. During the consult be sure to mention:

  • Any bad reactions your pet has suffered in the past to penicillins, carbapenems, cefamycins or cephalosporins
  • If your pet is taking bacteriostatic antimicrobials, methotrexate or probenicid
  • Any serious illness affecting your pet

Giving the tablets with food helps to lower the chance of vomiting and other gastric effects.

Note: Stopping treatment early could result in the infection returning, even if your dog seems to be feeling better. Keep administering it as usual for at least two full days (48 hours) after the symptoms of infection have gone away.


Vets prescribe amoxicillin to treat susceptible bacterial infections. If the bacteria produces beta lactamase plain formulations are not effective and combination drugs such as Clavamox® are used instead.

Side Effects

Adverse effects of this drug are usually restricted to vomiting and diarrhea. Allergic reactions, rapid breathing, breathlessness, raised heart rate, edema or superinfection can also occur.

If any serious reactions occur after administering amoxicillin stop use and seek immediate veterinary attention.


Dr. R. Appel
Plumb’s Veterinary Drug Handbook (sixth edition)
Zoetis (manufacturer)