Amoxicillin Dosage for Dogs: Complete Safety & Dosing Guide

What Is Amoxicillin and What Is It Used for in Dogs?

Amoxicillin is a broad-spectrum aminopenicillin antibiotic belonging to the beta-lactam drug class. It's one of the most commonly prescribed antibiotics in veterinary medicine due to its effectiveness against a wide range of gram-positive and some gram-negative bacteria, its relatively low side-effect profile, and its affordability.

The U.S. Food and Drug Administration (FDA) has approved veterinary amoxicillin (commonly sold under brand names like Amoxi-Tabs®, Amoxi-Drop®, and Biomox®) for treating susceptible bacterial infections in dogs. According to the Merck Veterinary Manual, amoxicillin is particularly effective against Streptococcus, Staphylococcus (non-beta-lactamase producing), Escherichia coli, Salmonella, and Proteus mirabilis.

FDA-Approved Veterinary Uses

• Skin and soft tissue infections — abscesses, cellulitis, pyoderma, wound infections
• Urinary tract infections (UTIs) — uncomplicated bacterial cystitis
• Respiratory tract infections — bacterial pneumonia, tracheobronchitis
• Gastrointestinal infections — bacterial enteritis caused by susceptible organisms

Common Off-Label Uses

Veterinarians may also prescribe amoxicillin off-label for:

• Dental infections and post-extraction prophylaxis
• Otitis externa (ear infections) when bacterial culture confirms susceptibility
• Prophylactic use before certain surgical procedures
• Lyme disease (as an alternative to doxycycline in puppies under 6 months)
• Leptospirosis (as part of initial treatment protocols)

Typical Amoxicillin Dosage for Dogs by Weight and Condition

The standard amoxicillin dosage for dogs ranges from 5 to 10 mg per pound (10–20 mg/kg) of body weight, given every 12 to 24 hours. Your veterinarian will determine the exact dose based on the infection type, severity, your dog's kidney function, and culture results when available.

Amoxicillin Dosage Table by Condition

Condition	Dose (mg/kg)	Dose (mg/lb)	Frequency	Typical Duration
Skin & soft tissue infections	10–20 mg/kg	5–10 mg/lb	Every 12 hours	7–14 days
Urinary tract infections	10–20 mg/kg	5–10 mg/lb	Every 12 hours	7–14 days
Respiratory infections	10–20 mg/kg	5–10 mg/lb	Every 12 hours	10–21 days
Dental infections	10–15 mg/kg	5–7 mg/lb	Every 12 hours	5–10 days
GI infections	10–20 mg/kg	5–10 mg/lb	Every 12–24 hours	5–7 days

Practical Dosing Examples

Here's what these numbers look like for common dog sizes at the mid-range dose of 10 mg/lb (22 mg/kg) every 12 hours:

Dog Weight	Per-Dose Amount	Common Tablet Size
10 lb (4.5 kg)	50 mg	50 mg tablet
25 lb (11.3 kg)	125 mg	125 mg tablet or capsule
50 lb (22.7 kg)	250 mg	250 mg capsule
75 lb (34 kg)	375 mg	250 mg + 125 mg tablets
100 lb (45.4 kg)	500 mg	500 mg tablet or 2× 250 mg

Important: These are reference examples only. Your veterinarian will prescribe the exact dose and tablet size for your dog's specific condition and weight. Never split or combine tablets to approximate a dose without veterinary guidance.

How to Administer Amoxicillin to Your Dog

Veterinary amoxicillin comes in several formulations designed to make dosing easier:

• Chewable tablets (Amoxi-Tabs®) — beef or liver flavored, scored for splitting. Most palatable option for dogs that accept treats readily.
• Capsules (Biomox®) — gelatin capsules, can be hidden in pill pockets or a small amount of wet food.
• Oral suspension (Amoxi-Drop®) — liquid form, ideal for small dogs and puppies. Must be shaken well before each dose and refrigerated after reconstitution. Discard after 14 days.
• Injectable — administered in-clinic by veterinary staff, typically reserved for severe infections or dogs that cannot tolerate oral medication.

With or Without Food?

Amoxicillin can be given with or without food. However, if your dog experiences nausea or vomiting after a dose on an empty stomach, giving subsequent doses with a small meal often resolves the issue. The absorption of amoxicillin is not significantly affected by food, unlike some other antibiotics (e.g., doxycycline).

Administration Tips

• Give doses at consistent 12-hour intervals (e.g., 7 AM and 7 PM) to maintain steady blood levels.
• For liquid suspensions, use the calibrated syringe provided — household teaspoons are inaccurate.
• If hiding a pill in food, use a small amount (a spoonful of canned food or a pill pocket) to ensure the full dose is consumed.
• Always complete the entire prescribed course, even if your dog appears fully recovered within a few days. Stopping early promotes antibiotic-resistant bacteria.

Side Effects of Amoxicillin in Dogs

Amoxicillin is generally well-tolerated, but like all medications, it can cause adverse reactions. Understanding the frequency and severity of potential side effects helps you monitor your dog appropriately.

Side Effects Frequency Table

Side Effect	Frequency	Severity	Action
Vomiting	Common (~10–15%)	Mild	Give with food; call vet if persistent >24 hours
Diarrhea / loose stools	Common (~10–15%)	Mild to moderate	Add probiotic; call vet if bloody or >48 hours
Decreased appetite	Uncommon (~5%)	Mild	Offer bland diet; monitor hydration
Drooling (from taste)	Uncommon (~5%)	Mild	Try hiding in food or switch to capsule form
Allergic reaction (hives, facial swelling)	Rare (<1%)	Serious	Stop medication, contact vet immediately
Anaphylaxis (collapse, difficulty breathing)	Very rare (<0.1%)	Life-threatening	Emergency — go to nearest vet ER immediately
Severe bloody diarrhea (C. diff overgrowth)	Rare (<1%)	Serious	Stop medication, contact vet immediately

Contraindications: Dogs Who Should Not Receive Amoxicillin

While amoxicillin is one of the safest antibiotics in veterinary medicine, certain dogs should not receive it or require modified protocols:

• Known penicillin or cephalosporin allergy: Dogs that have had a previous allergic reaction to any penicillin-class drug (amoxicillin, ampicillin, penicillin G) or cephalosporins (cephalexin, cefpodoxime) should not receive amoxicillin. Cross-reactivity between penicillins and cephalosporins occurs in approximately 1–3% of cases.
• Severe kidney disease: Amoxicillin is primarily excreted by the kidneys. Dogs with advanced chronic kidney disease (CKD Stage 3–4) may require dose reduction or extended dosing intervals to prevent drug accumulation and toxicity.
• History of antibiotic-associated colitis: Dogs that have previously developed Clostridioides difficile overgrowth or severe antibiotic-associated diarrhea may need an alternative antibiotic or concurrent probiotic therapy.
• Pregnant or nursing dogs: Amoxicillin is generally considered safe during pregnancy (Category B in human medicine), but your veterinarian will weigh risks and benefits for breeding or lactating dogs.

Drug Interactions to Be Aware Of

Amoxicillin can interact with other medications your dog may be taking. Always provide your veterinarian with a complete list of all current medications, supplements, and over-the-counter products.

Drug Interaction Grid

Drug / Supplement	Interaction Type	Clinical Significance	Management
Bacteriostatic antibiotics (tetracycline, chloramphenicol, erythromycin)	Antagonistic	Moderate — bacteriostatic drugs may reduce amoxicillin effectiveness since it requires actively dividing bacteria to work	Avoid concurrent use; vet may choose alternative
Probenecid	Pharmacokinetic	Moderate — probenecid blocks renal excretion of amoxicillin, increasing blood levels and half-life	Dose adjustment may be needed
Methotrexate	Increased toxicity	High — amoxicillin reduces renal clearance of methotrexate, increasing risk of bone marrow suppression	Avoid combination or closely monitor blood counts
Oral bacterin vaccines (e.g., Bordetella oral vaccine)	Reduced vaccine efficacy	Moderate — antibiotics may kill the live attenuated bacteria in oral vaccines	Separate antibiotic course from oral vaccine by at least 7 days
Probiotics	Reduced probiotic efficacy	Low — amoxicillin may kill beneficial bacteria in probiotic supplements	Give probiotics 2–3 hours apart from amoxicillin dose
Allopurinol (used for Leishmaniasis, urate stones)	Increased rash risk	Low to moderate — concurrent use in humans increases skin rash incidence; limited veterinary data	Monitor for skin reactions

How Long Does My Dog Need to Be on Amoxicillin?

Treatment duration depends on the infection type, severity, and your dog's response. General guidelines:

• Mild skin infections: 7–14 days
• Uncomplicated UTIs: 7–14 days (veterinary guidelines increasingly favor 3–5 day courses for first-time, uncomplicated UTIs based on antimicrobial stewardship recommendations)
• Deep pyoderma or severe skin infections: 3–6 weeks, sometimes with follow-up culture
• Respiratory infections: 10–21 days
• Dental infections: 5–10 days, often beginning 2–3 days before a dental procedure

A general rule in veterinary antibiotic therapy is to continue treatment for at least 48 hours beyond clinical resolution of symptoms. However, your veterinarian will set the specific course length. Do not stop early because your dog "looks better" — incomplete courses are a primary driver of antibiotic-resistant infections.

Monitoring Requirements

For short courses (under 14 days) in otherwise healthy dogs, monitoring is typically limited to:

• Owner observation for side effects (GI upset, appetite changes, allergic signs)
• Phone check-in with the veterinary clinic at day 3–5 to assess response

For extended courses (over 14 days) or dogs with pre-existing conditions, your veterinarian may recommend:

Monitoring Schedule for Extended Amoxicillin Use

Timepoint	Monitoring Action	Purpose	Estimated Cost
Day 5–7	Recheck exam or phone consultation	Assess clinical response, adjust if no improvement	$50–$85 (recheck exam)
Day 14	Bacterial culture & sensitivity (if not done initially)	Confirm susceptibility if infection not resolving	$80–$180
Day 21+ (extended courses)	CBC and chemistry panel	Monitor kidney and liver function, check for bone marrow effects	$120–$250
End of course	Final recheck exam	Confirm infection resolution, determine if further treatment needed	$50–$85

Missed Dose and Overdose: What to Do

If You Miss a Dose

Give the missed dose as soon as you remember. However, if it's nearly time for the next scheduled dose, skip the missed dose and continue with the regular schedule. Never give a double dose to make up for a missed one — this increases the risk of GI side effects without improving efficacy.

If you've missed more than two consecutive doses, contact your veterinarian. Gaps in antibiotic therapy can allow bacteria to regrow and potentially develop resistance, which may require a different antibiotic entirely.

If an Overdose Occurs

Amoxicillin has a relatively wide safety margin, and a single extra dose is unlikely to cause serious harm in most dogs. The most likely consequence is gastrointestinal upset — vomiting, diarrhea, and decreased appetite.

However, massive overdoses (several times the prescribed amount) can cause:

• Crystal formation in the urine (crystalluria) leading to kidney damage
• Severe vomiting and diarrhea with dehydration risk
• Neurological signs (seizures) in extreme cases, particularly in dogs with pre-existing kidney impairment

If your dog ingests a significant overdose:

1. Do not induce vomiting unless directed by a veterinarian.
2. Call your veterinarian or emergency clinic immediately.
3. Contact ASPCA Animal Poison Control at (888) 426-4435 (24/7, consultation fee applies) for guidance.
4. Have the medication bottle available to report the exact milligram strength and estimated quantity consumed.

Cost, Availability, and Alternatives to Amoxicillin

Cost Range

Amoxicillin is one of the most affordable veterinary antibiotics. Pricing varies by formulation, dosage, and pharmacy:

Formulation	Typical Price Range	Notes
Generic tablets (500 mg, 30-count)	$8–$25	Widely available at online and compounding pharmacies
Brand-name tablets (Amoxi-Tabs®, 30-count)	$20–$45	Chewable, flavored; may improve compliance
Oral suspension (Amoxi-Drop®, 15 mL)	$15–$35	Must be refrigerated after reconstitution; 14-day shelf life
Injectable (in-clinic)	$25–$60 per injection	Includes administration fee; used for severe cases

Generic veterinary amoxicillin is widely available through online pharmacies (Chewy, 1-800-PetMeds) and most brick-and-mortar pharmacies that fill veterinary prescriptions. Ask your vet if they can send the prescription to your preferred pharmacy for the best price.

Alternatives to Amoxicillin

If your dog cannot tolerate amoxicillin, has a known allergy, or the infecting bacteria are resistant, your veterinarian may consider these alternatives:

• Amoxicillin-clavulanate (Clavamox®): Adds a beta-lactamase inhibitor for resistant organisms. Often the first step up when plain amoxicillin fails.
• Cephalexin (Simplicef®): First-generation cephalosporin with similar spectrum; excellent for skin infections. Note: cross-allergy risk in penicillin-allergic dogs (~1–3%).
• Doxycycline: Broad-spectrum tetracycline; preferred for tick-borne diseases (Lyme, Ehrlichia), respiratory infections, and atypical organisms. Avoid in puppies under 6 months due to tooth discoloration risk.
• Enrofloxacin (Baytril®): Fluoroquinolone reserved for resistant gram-negative infections. Used judiciously due to cartilage damage risk in growing dogs and its importance as a last-resort class.
• Clindamycin (Antirobe®): Excellent bone and dental tissue penetration; commonly used for deep pyoderma, osteomyelitis, and dental infections.

Your veterinarian's choice of alternative will be guided by bacterial culture and sensitivity results whenever possible, following antimicrobial stewardship principles endorsed by the American Veterinary Medical Association (AVMA).

Frequently Asked Questions