Isoxazoline antiparasitic · For Dogs
NexGard dosage reference for dogs (Afoxolaner)
This page's standard weight-based reference is 2.5 mg per kg (1.13 mg per lb), with once monthly recorded as the reference frequency. Use the calculator to see the arithmetic for your dog's weight, then confirm the indication, product, and actual dose with a veterinarian.
- Onset
- 4-8 hours
- Duration
- 30 days
- Class
- Isoxazoline antiparasitic
Weight-based calculator estimate from the references listed on this page. This page has not been independently DVM-reviewed — see our methodology .
This information is for educational purposes only. Always consult your veterinarian before giving medication to your pet. Do not use this calculator for emergencies, overdoses, pregnancy, very young animals, very old animals, pets with liver/kidney disease, or pets taking multiple medications.
Each medication page lists the references recorded for its data. The calculator math and editorial presentation are maintained by PetDosageChart; a page is independently DVM-reviewed only when a named reviewer byline appears. See our methodology and limitations.
Afoxolaner (often known by brand names such as NexGard) is an isoxazoline antiparasitic commonly used in veterinary medicine for flea treatment and prevention and tick treatment and prevention. Understanding the correct dosage, administration, and potential side effects of Afoxolaner is critical for your dog’s safety and well-being.
A typical Afoxolaner dose for dogs is around 2.5 mg/kg once monthly, within a usual range of 2.5-5 mg/kg. Available forms include chewable tablet.
Calculator Warning: Use this only as an educational estimate. Your veterinarian may prescribe a different dose based on your pet’s condition, age, weight, other medications, and medical history.
Afoxolaner Dosage Calculator for Dogs
Enter your dog’s weight below to estimate the Afoxolaner dose from the 2.5 mg/kg guideline. Your veterinarian may adjust it for your dog’s age, condition, and other medications, so treat the result as an educational starting point, not a prescription.
Dosage Calculator · 01
Enter your dog's weight
Quick Dosage Chart
Typical Afoxolaner amounts for common dog weights, for quick reference:
Dosage Chart · 02
NexGard weight-based reference chart for dogs
Scroll sideways to see full table
| Weight | Lower Reference | Standard Reference | Upper Reference | Frequency |
|---|---|---|---|---|
| 5 lbs (2.3 kg) | 5.8 mg | 5.8 mg | 11.5 mg (11.3mg tablet) | once monthly |
| 10 lbs (4.5 kg) | 11.3 mg (11.3mg tablet) | 11.3 mg (11.3mg tablet) | 22.5 mg (2 × 11.3mg) | once monthly |
| 15 lbs (6.8 kg) | 17.0 mg | 17.0 mg | 34.0 mg (3 × 11.3mg) | once monthly |
| 20 lbs (9.1 kg) | 22.8 mg (2 × 11.3mg) | 22.8 mg (2 × 11.3mg) | 45.5 mg (4 × 11.3mg) | once monthly |
| 25 lbs (11.3 kg) | 28.3 mg | 28.3 mg | 56.5 mg (5 × 11.3mg) | once monthly |
| 30 lbs (13.6 kg) | 34.0 mg (3 × 11.3mg) | 34.0 mg (3 × 11.3mg) | 68.0 mg (6 × 11.3mg) | once monthly |
| 40 lbs (18.1 kg) | 45.3 mg (4 × 11.3mg) | 45.3 mg (4 × 11.3mg) | 90.5 mg (8 × 11.3mg) | once monthly |
| 50 lbs (22.7 kg) | 56.8 mg (5 × 11.3mg) | 56.8 mg (5 × 11.3mg) | 113.5 mg (10 × 11.3mg) | once monthly |
| 60 lbs (27.2 kg) | 68.0 mg (6 × 11.3mg) | 68.0 mg (6 × 11.3mg) | 136.0 mg (12 × 11.3mg) | once monthly |
| 70 lbs (31.7 kg) | 79.3 mg (7 × 11.3mg) | 79.3 mg (7 × 11.3mg) | 158.5 mg (14 × 11.3mg) | once monthly |
| 80 lbs (36.3 kg) | 90.8 mg (8 × 11.3mg) | 90.8 mg (8 × 11.3mg) | 181.5 mg (16 × 11.3mg) | once monthly |
| 90 lbs (40.8 kg) | 102.0 mg (9 × 11.3mg) | 102.0 mg (9 × 11.3mg) | 204.0 mg (18 × 11.3mg) | once monthly |
| 100 lbs (45.4 kg) | 113.5 mg (10 × 11.3mg) | 113.5 mg (10 × 11.3mg) | 227.0 mg (20 × 11.3mg) | once monthly |
| 120 lbs (54.4 kg) | 136.0 mg (12 × 11.3mg) | 136.0 mg (12 × 11.3mg) | 272.0 mg (24 × 11.3mg) | once monthly |
| 150 lbs (68 kg) | 170.0 mg (15 × 11.3mg) | 170.0 mg (15 × 11.3mg) | 340.0 mg (30 × 11.3mg) | once monthly |
Parenthetical tablet amounts are arithmetic comparisons only. They do not account for scoring, release type, concentration, product labeling, or whether this medication is appropriate for an individual animal.
By Weight
NexGard reference by dog weight
Choose a common weight to open its optional reference page. Use the main medication calculator for a different exact weight.
Common-weight pages are convenience views of the same educational reference, not separate medical recommendations.
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How to Give Afoxolaner to Your Dog
NexGard is a beef-flavored chewable tablet given once monthly. Most dogs eat it like a treat. Give on the same day each month. NexGard only covers fleas and ticks — you will need a separate heartworm preventive. Can be given with or without food.
It is generally recommended to give Afoxolaner with food to help reduce stomach upset. It may interact with other isoxazoline products and P-glycoprotein inhibitors.
Side Effects and Safety
Common side effects include vomiting, diarrhea, lethargy, decreased appetite, and dry skin. More serious side effects can occur, such as seizures (rare), tremors, ataxia, and severe vomiting.
Cautions · 12
When NexGard should be used with caution or avoided
Some dogs should not take NexGard, or need a different dose and closer monitoring. Tell your veterinarian about your pet's full health history and every other medication or supplement they take before giving NexGard.
- puppies under 8 weeks
- dogs under 4 lbs
- dogs with seizure history (use with caution)
Interactions · 13
NexGard drug interactions
NexGard can interact with other drugs. This list is not complete — always give your veterinarian a full list of your dog's medications and supplements.
Calculator Limits · 14
When not to use this calculator
This calculator gives a general educational estimate for a healthy adult dog at a known weight. Do not rely on it in these situations — talk to your veterinarian instead:
- In an emergency, or after accidental ingestion or a suspected overdose
- For pregnant or nursing pets
- For very young or very old dogs
- For pets with liver disease, kidney disease, or another chronic illness
- For pets taking several medications at once
- When you are not sure of your dog's current, accurate weight
- For combination products that contain additional active ingredients
Overdose · 15
Suspected overdose: what to do
If you think your dog had too much NexGard, or swallowed any medication by accident, act right away. Do not wait for symptoms to appear.
- Call your veterinarian or the nearest emergency animal hospital.
- ASPCA Animal Poison Control Center: (888) 426-4435
- Pet Poison Helpline: (855) 764-7661
A consultation fee may apply to the poison hotlines. Have the medication packaging ready, and note how much your pet may have taken and when. Do not try to make your pet vomit unless a veterinarian tells you to.
When to Call the Vet
If your dog experiences any of the following, contact your veterinarian or an emergency clinic immediately:
- Seizures or tremors after dosing
- Severe or persistent vomiting
- Lethargy lasting more than 24 hours
- You still see fleas or ticks after treatment
- Signs of allergic reaction
Frequently Asked Questions
Frequently Asked · 07
Questions about this medication
How fast does NexGard kill fleas?
Does NexGard prevent heartworm?
Is NexGard safe for dogs?
Can I give NexGard to my puppy?
Use This Guide Safely · 08
What weight alone cannot tell you
The calculator performs one narrow job: it multiplies your dog's weight by the lower, standard, and upper mg/kg values recorded for NexGard. It cannot decide whether this drug, indication, formulation, or schedule is appropriate for an individual animal.
Context in this medication record
- Commonly listed uses
- flea treatment and prevention, tick treatment and prevention
- Recorded forms
- chewable tablet
- Reference timing
- once monthly; onset 4-8 hours; duration 30 days
Individual checks a calculator cannot perform
- Confirm the diagnosis and the reason this medication is being considered.
- Match the exact product, concentration, route, and whether a tablet may be split.
- Account for age, pregnancy, organ function, genetics, allergies, and prior reactions.
- Review every prescription, over-the-counter product, and supplement your pet takes.
Recorded cautions
puppies under 8 weeks; dogs under 4 lbs; dogs with seizure history (use with caution).
Recorded interactions
other isoxazoline products; P-glycoprotein inhibitors.
These lists reproduce the structured record used by this page and may not be exhaustive. Show your veterinarian the product label and your dog's complete medication list before acting on a number.
Related · 08
Related medications for dogs
- Isoxazoline antiparasiticCredelioLotilaner · For Flea treatment and prevention
- AntiparasiticIvomecIvermectin · For heartworm prevention
- Antiparasitic combinationSimparica TrioSarolaner / Moxidectin / Pyrantel · For flea prevention
- Antiparasitic combinationHeartgard PlusIvermectin / Pyrantel · For heartworm prevention
Sources · 09
Sources & references
The structured medication record behind this page names the references below. The links open the publisher or official resource; they do not turn this page into a prescription for an individual animal.
- Plumb's Veterinary Drug Handbook — listed in this medication's source record.
- Merck Veterinary Manual — listed in this medication's source record.
- DailyMed label search for Afoxolaner — check current product and formulation labels; some veterinary uses may be off-label.
Source names are shown at the record level; passage-level page and label citations are still being added. Read our methodology and limitations.
Transparency · 11
How this page was made
This page's structured medication record includes Plumb's Veterinary Drug Handbook among its source names. PetDosageChart applies the record's mg/kg values to the entered weight and presents the arithmetic result. A source record is not the same as an individualized prescription or an independent clinical review.
- Sources cited
-
- Plumb's Veterinary Drug Handbook
- Merck Veterinary Manual
- Calculator formula
- Doses scale linearly from a standard basis of 2.5 mg per kg (1.13 mg per lb) of body weight, given once monthly. The calculator multiplies that basis by your dog's weight and shows an arithmetic comparison with recorded tablet sizes. That comparison does not determine whether a tablet is scored, splittable, or appropriate for your pet.
- Editorial owner
- Prepared and maintained by the PetDosageChart editorial team, a software-led publisher and not a veterinary practice.
- DVM review status
- Not independently DVM-reviewed. A named reviewer and review date appear here only after a confirmed review.
More on our methodology and editorial process — how we source, calculate, and review dogs dosage data.
Safety · 10
More resources
- Pet Medication Safety Hub — What's safe, what's dangerous, and emergency signs
- How we calculate dosages — Our sources, math, and review process
- Printable emergency checklist — One-page reference for your fridge or first aid kit