Medication Guide • Reviewed by Dr. Tiffany Delacruz, DVM
Amoxicillin for Dogs
Amoxicillin is a prescription antibiotic used to treat a range of bacterial infections in dogs — including skin, urinary tract, respiratory, and dental infections.
What Amoxicillin is used for in dogs
- Skin infections (pyoderma)
- Urinary tract infections
- Some respiratory infections
- Dental infections
- Soft tissue infections
How it works
Amoxicillin disrupts bacterial cell wall synthesis, killing susceptible bacteria. It is broad-spectrum but not effective against every type of bacteria — culture and sensitivity testing may be needed for resistant infections.
Available formulations
50 mg tablet
100 mg tablet
200 mg tablet
400 mg tablet
Oral suspension
Side effects to know
Common side effects
- • Mild GI upset
- • Diarrhea
- • Decreased appetite
These usually resolve on their own. If they persist past the first few doses, ask your vet.
Call your vet immediately if you see
- ⚠ Severe allergic reaction (facial swelling, hives, difficulty breathing)
- ⚠ Severe persistent diarrhea (may indicate C. difficile overgrowth)
- ⚠ Yeast overgrowth with long courses
Drug interactions
- • Other antibiotics (tetracyclines can reduce effectiveness)
- • Probenecid (increases amoxicillin levels)
When not to use
- • Dogs with known penicillin allergy
- • Caution in dogs with severe kidney disease (dose adjustment needed)
Monitoring during treatment
Complete the full course even if symptoms improve. Stopping early breeds antibiotic resistance.
Need a Amoxicillin refill?
RexVet is the first 501(c)(3) non-profit online vet service in the U.S. Talk to a licensed veterinarian by video, get your dogs's Amoxicillin prescription, and have it shipped through RexVetRx — all for $64.99 per visit.
Book a vet visit — $64.99Amoxicillin for Dogs
Frequently asked questions
How long does it take amoxicillin to work in dogs?
Most dogs show clinical improvement within 48-72 hours. Continue the full course even if your dog seems better — stopping early can cause resistance and recurrence.
Can I give my dog human amoxicillin?
Same active ingredient, but human formulations may have inactive ingredients dogs shouldn't have (especially flavorings with xylitol). Always use vet-prescribed amoxicillin.
Why is my dog having diarrhea on amoxicillin?
Mild diarrhea is common with antibiotics because they disrupt gut bacteria. If diarrhea is severe, bloody, or persistent, contact your vet — sometimes a probiotic or different antibiotic helps.
Can RexVet prescribe amoxicillin?
Yes — for clearly diagnosable conditions like uncomplicated skin or urinary infections, a RexVet video visit can result in amoxicillin shipped through RexVetRx the same day.
What if my dog vomits up the amoxicillin?
If within 1 hour of dosing, contact your vet — they may recommend repeating the dose with food. After 1 hour, the dose was absorbed.
Medical review by Dr. Tiffany Delacruz, DVM
Chief Executive Officer & Lead Veterinarian, RexVet. Licensed in Florida, New York, and Virginia.
Last fact-checked: 2026-05-19
Sources
This page is an educational reference and does not replace veterinary advice. Always consult a licensed veterinarian before starting, changing, or stopping medication for your pet.