Amoxicillin is a broad-spectrum antibiotic vets commonly prescribe for dogs to treat bacterial infections of the skin, urinary tract, and respiratory system. Dosage is calculated by body weight and prescribed by a vet, typically given two to three times daily for a set course, and it’s usually paired with clavulanic acid to broaden its effectiveness against resistant bacteria.

Medically reviewed by Dr. Dinesh Moliya, B.V.Sc & A.H, M.V.Sc & A.H — 16 years of clinical veterinary experience.

Amoxicillin is one of the most frequently prescribed antibiotics in veterinary medicine, but effective use depends on correct dosing, completing the full course, and watching for the right side effects. Here’s what owners should know before and during treatment.

What Amoxicillin Treats in Dogs

• Skin infections, including secondary infections from wounds or hot spots
• Urinary tract infections
• Respiratory infections
• Certain dental infections
• Some gastrointestinal bacterial infections

Why It’s Often Combined with Clavulanate

Amoxicillin alone can be broken down by certain bacterial enzymes that make the bacteria resistant to it. Combining it with clavulanic acid blocks that resistance mechanism, which is why many veterinary products — including Amoxycillin & Clavulanate combinations — are prescribed over plain amoxicillin for a broader range of infections.

How Dosing Works

Dosage is calculated based on the dog’s body weight and the type of infection being treated, and is prescribed by a vet rather than estimated at home. Courses are typically given two to three times daily and usually run for 7–14 days, though the exact length depends on the infection.

Completing the full prescribed course — even after symptoms improve — matters because stopping early is one of the most common causes of antibiotic resistance and infection relapse.

Side Effects to Watch For

• Mild gastrointestinal upset — the most common side effect, often manageable by giving the medication with food
• Loss of appetite
• Diarrhea or soft stool
• Rarely, allergic reactions such as facial swelling or hives — requires immediate vet attention

Amoxicillin at a Glance

Frequently Asked Questions

Can I give my dog amoxicillin without a vet prescription?

No — correct dosing depends on your dog’s weight and the specific infection, and using it without veterinary guidance risks under-dosing, side effects, or antibiotic resistance.

How long does it take amoxicillin to work in dogs?

Many dogs show improvement within 48–72 hours, but the full prescribed course should still be completed even after symptoms improve, to fully clear the infection.

What happens if I stop antibiotics early?

Stopping early is one of the leading causes of infection relapse and can contribute to antibiotic resistance, making the infection harder to treat the next time.

Is amoxicillin safe for puppies?

It can be used in puppies under veterinary guidance, with dosing adjusted carefully for their smaller body weight and developing systems.

Why is amoxicillin sometimes combined with clavulanic acid?

The combination blocks a resistance mechanism some bacteria use against amoxicillin alone, making it effective against a broader range of infections.

What are the signs of an allergic reaction to amoxicillin?

Facial swelling, hives, or difficulty breathing are signs of a serious allergic reaction and require immediate veterinary attention rather than waiting out the dose.

Should I give amoxicillin with food?

Giving it with food is commonly recommended to reduce the chance of mild gastrointestinal upset, one of the most frequent side effects.

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