NexGard Plus Chewable Tablets for Dogs
Everything you need to know about NexGard Plus chewable tablets for dogs—dosage, side effects, cost, drug interactions, and vet-recommended alternatives.
⚕️ PRESCRIPTION-ONLY NOTICE: NexGard Plus is a prescription veterinary medication. It requires a valid veterinarian-client-patient relationship (VCPR) and should only be administered under direct veterinary supervision. Never use this product without a current prescription from your dog's veterinarian. Dosage adjustments must always be made by your vet, not at home.
If your veterinarian has recommended NexGard Plus for your dog, you likely have questions about how it works, what to watch for, and whether it's the right long-term choice. This guide breaks down every aspect of NexGard Plus chewable tablets for dogs—from the parasitology behind its triple-action formula to real-world cost expectations in 2026.
What Is NexGard Plus and What Is It Used For?
NexGard Plus is a monthly oral chewable parasiticide manufactured by Boehringer Ingelheim. It combines three active ingredients to provide broad-spectrum protection against external and internal parasites in a single beef-flavored chew. The FDA approved NexGard Plus for use in dogs and puppies 8 weeks of age and older, weighing at least 4.5 lb (2 kg).
FDA-Approved Indications
- Flea treatment and prevention — kills adult fleas (Ctenocephalides felis) and prevents flea infestations for one month
- Tick control — kills the lone star tick, American dog tick, black-legged tick (deer tick), and brown dog tick
- Heartworm disease prevention — prevents infection by Dirofilaria immitis
- Intestinal parasite treatment — treats and controls roundworm (Toxocara canis) and hookworm (Ancylostoma caninum) infections
Common Off-Label Uses
While NexGard Plus is not officially labeled for these conditions, veterinarians sometimes recommend it as part of a broader protocol for:
- Sarcoptic mange (scabies) — afoxolaner has demonstrated efficacy against Sarcoptes scabiei mites in clinical settings, and your vet may prescribe the afoxolaner component (NexGard) off-label for mange management
- Demodectic mange — isoxazoline-class drugs have shown strong efficacy against Demodex canis, though NexGard Plus specifically is not the first-line choice for demodicosis treatment protocols
Always consult your veterinarian before relying on NexGard Plus for any off-label purpose. Your vet will determine whether the standard monthly dose is sufficient or if a modified protocol is needed.
How Does NexGard Plus Work? Mechanism of Action Explained
Triple-Active Mechanism
NexGard Plus delivers three distinct pharmacological attacks on parasites:
1. Afoxolaner (Isoxazoline class) — 13.6 mg to 136 mg per chew depending on weight
Afoxolaner targets the parasite's central nervous system by inhibiting GABA-gated and glutamate-gated chloride channels. This causes uncontrolled neural excitation in fleas and ticks, leading to hyperexcitation, paralysis, and death. Because mammals process GABA differently, afoxolaner selectively affects invertebrate nervous systems with a wide safety margin in dogs.
2. Moxidectin (Macrocyclic lactone class) — 2.7 mcg to 27 mcg per chew
Moxidectin prevents heartworm disease by eliminating the tissue-stage larvae (L3 and L4) of Dirofilaria immitis before they mature into adult worms in the pulmonary arteries. It works by binding to glutamate-gated chloride channels in the larvae, causing flaccid paralysis and death.
3. Pyrantel (Tetrahydropyrimidine class) — 5.4 mg to 54 mg per chew
Pyrantel acts as a depolarizing neuromuscular blocking agent in intestinal nematodes (roundworms and hookworms). It causes sudden contraction followed by paralysis of the worm's body wall muscles, allowing the parasite to be expelled through normal intestinal peristalsis.
The combination is significant because it replaces what would otherwise require two or three separate products—a standalone flea/tick preventive (like original NexGard), a heartworm preventive (like Heartgard), and a dewormer (like Nemex). This consolidation improves compliance; according to the American Veterinary Medical Association, missed doses of heartworm preventive are a leading cause of breakthrough infections.
Typical Dosage of NexGard Plus by Dog Weight
Your veterinarian will prescribe the correct chew size based on your dog's current body weight. NexGard Plus is available in five weight-based formulations. The minimum effective dosages are approximately 1.1 mg/lb (2.5 mg/kg) afoxolaner, 0.025 mg/lb (0.05 mg/kg) moxidectin, and 2.3 mg/lb (5 mg/kg) pyrantel (as pyrantel pamoate).
| Dog Weight Range | Chew Color | Afoxolaner | Moxidectin | Pyrantel |
|---|---|---|---|---|
| 4.5 – 10 lb (2 – 4.5 kg) | Green | 13.6 mg | 2.7 mcg | 5.4 mg |
| 10.1 – 24 lb (4.6 – 10.9 kg) | Blue | 34 mg | 6.8 mcg | 13.5 mg |
| 24.1 – 60 lb (11 – 27.2 kg) | Purple | 68 mg | 13.6 mcg | 27 mg |
| 60.1 – 121.5 lb (27.3 – 55 kg) | Orange | 136 mg | 27 mcg | 54 mg |
| Over 121.5 lb (55+ kg) | Combination | Multiple chews prescribed by your vet to reach correct dose | ||
Administration instructions: NexGard Plus can be given with or without food. The chew is beef-flavored and most dogs accept it readily. If your dog spits out any portion of the chew, observe how much was consumed. If a significant portion was rejected, contact your veterinarian for guidance on redosing. Do not split chews to save money—each chew is formulated as a complete unit dose.
Frequency: Once monthly, year-round. The American Heartworm Society recommends 12-month annual heartworm prevention regardless of geographic location, as mosquito activity is increasingly unpredictable with changing climate patterns.
Side Effects: What to Watch For
In FDA pivotal field studies and post-approval surveillance, NexGard Plus demonstrated a favorable safety profile. However, no medication is without potential adverse effects. Here's what the data shows:
Common Side Effects (Reported Frequency)
| Side Effect | Approximate Frequency | Typical Duration |
|---|---|---|
| Vomiting | ~2–4% | Usually within 24 hours of dosing |
| Diarrhea / soft stool | ~1–3% | 1–2 days, self-resolving |
| Lethargy | ~1–2% | 12–24 hours |
| Decreased appetite | ~1–2% | 1–2 meals missed |
| Pruritus (itching) | <1% | Variable, often dying-flea reaction |
🚨 Serious Side Effects — Contact Your Veterinarian Immediately
- Seizures or muscle tremors — The isoxazoline class (afoxolaner) has been associated with neurologic adverse events, including seizures, in dogs with or without a history of epilepsy. The FDA issued a safety alert in 2018 regarding this class-wide risk. While events remain rare, dogs with pre-existing seizure disorders require careful risk-benefit evaluation.
- Ataxia (loss of coordination or stumbling)
- Persistent vomiting (more than 2 episodes within 24 hours)
- Bloody diarrhea
- Facial swelling, hives, or difficulty breathing (signs of anaphylaxis)
- Jaundice (yellowing of gums, eyes, or skin)
If any of these occur, stop the medication and contact your veterinarian or an emergency clinic immediately. For accidental ingestion by humans or toxic exposure concerns, call ASPCA Animal Poison Control at (888) 426-4435 (24/7, consultation fee applies).
Contraindications: Which Dogs Should NOT Receive NexGard Plus?
NexGard Plus is not appropriate for every dog. Your veterinarian will screen for the following contraindications before prescribing:
- Puppies under 8 weeks of age — Safety has not been established in very young puppies
- Dogs weighing less than 4.5 lb (2 kg) — The smallest chew size is formulated for dogs at or above this weight threshold
- Dogs with a known hypersensitivity to afoxolaner, moxidectin, pyrantel, or any excipient in the formulation
- Dogs with a history of seizures or epilepsy — The isoxazoline class carries an FDA warning for neurologic events. Your vet may recommend a non-isoxazoline alternative such as a topical or a different drug class
- Heartworm-positive dogs — NexGard Plus is a preventive, not a treatment for adult heartworm infection. Dogs must be tested negative for Dirofilaria immitis antigen before starting any heartworm preventive. Administering moxidectin to a heartworm-positive dog can trigger a severe inflammatory reaction from dying microfilariae
- MDR1 gene mutation carriers — Dogs with the multi-drug resistance 1 (MDR1) mutation (common in Collies, Australian Shepherds, and related herding breeds) have increased sensitivity to macrocyclic lactones like moxidectin. While the moxidectin dose in NexGard Plus is low, your veterinarian will weigh the risk and may recommend genetic testing via the WSU Veterinary Clinical Pharmacology Lab
Drug Interactions and Monitoring Requirements
Known Drug Interactions
| Concurrent Medication | Interaction Risk | Veterinary Guidance |
|---|---|---|
| Other isoxazolines (Bravecto, Simparica, Credelio) | Duplicate therapy — increased neurologic risk | Never combine; choose one flea/tick product only |
| Other macrocyclic lactones (Heartgard, Interceptor, Revolution) | Duplicate heartworm preventive — potential toxicity | Discontinue standalone HW preventive when starting NexGard Plus |
| Avermectins / high-dose ivermectin | Additive neurotoxic risk, especially in MDR1-positive dogs | Avoid concurrent use; vet will manage heartworm treatment separately |
| NSAIDs (carprofen, meloxicam, grapiprant) | No direct contraindication, but monitor GI tolerance | Generally safe; separate dosing by several hours if GI sensitivity |
| Phenobarbital / potassium bromide (anti-seizure meds) | Isoxazoline may lower seizure threshold | Vet will evaluate risk; may prefer non-isoxazoline flea/tick product |
Monitoring Schedule
Recommended Monitoring While on NexGard Plus
- Annual heartworm antigen test — Required before each prescription renewal. Cost: $35–$75 per test depending on your region and clinic
- Annual fecal flotation — NexGard Plus covers roundworms and hookworms, but does not cover whipworms, tapeworms, Giardia, or Coccidia. Annual fecal exam ($30–$60) ensures comprehensive intestinal parasite screening
- Weight checks at each refill — Growing puppies may move between weight brackets, requiring a different chew size. Obese dogs losing weight may need dose reduction
- Neurologic monitoring — If your dog has any history of seizures, your vet may schedule more frequent follow-up visits (every 3–6 months) during the first year of use
- No routine blood work required for NexGard Plus specifically, unless your dog has concurrent conditions or is on other medications that require hepatic/renal monitoring
How Long Does My Dog Need to Be on NexGard Plus?
Heartworm prevention is a year-round, lifelong commitment for virtually all dogs in the United States. The American Heartworm Society recommends continuous, 12-month annual prevention for all dogs, regardless of whether you live in a traditionally "high-risk" area. Mosquito vectors have been documented in all 50 states, and indoor dogs are not protected—mosquitoes enter homes readily.
For flea and tick control, duration depends on your geographic region and your dog's lifestyle. In warm-climate states (Florida, Texas, Southern California), year-round flea and tick prevention is standard. In northern states with distinct winters, some owners and veterinarians discuss seasonal protocols—but the trend in veterinary parasitology is shifting toward year-round coverage due to warming winters and indoor flea reservoirs.
For intestinal parasite control, NexGard Plus treats active roundworm and hookworm infections and provides ongoing monthly control. Dogs in high-exposure environments (dog parks, kennels, multi-dog households, hunting dogs) benefit from continuous coverage. Your veterinarian will tailor the duration based on annual fecal results and your dog's risk profile.
Missed Dose and Overdose Protocols
If You Miss a Monthly Dose
- Give the missed dose as soon as you remember. Do not wait until the next scheduled date.
- Reset your monthly schedule from the date you gave the late dose (not from the original due date).
- If the gap was less than 6 weeks, your dog is likely still protected against heartworm, as moxidectin has a residual effect window.
- If the gap exceeded 6 weeks, contact your veterinarian. They may recommend a heartworm antigen test at the next visit and may prescribe a macrocyclic lactone "reach-back" protocol (typically ivermectin-based) to eliminate any larvae that may have established during the gap.
- Set a recurring calendar reminder or use the Boehringer Ingelheim NexGard reminder app to prevent future lapses.
If an Overdose Occurs
In safety studies, NexGard Plus was administered at up to 5× the maximum labeled dose to puppies and adult dogs without serious adverse effects. However, accidental ingestion of multiple chews (for example, a dog getting into the medicine cabinet) can cause:
- Vomiting and hypersalivation
- Tremors or ataxia at very high doses
- Seizures in susceptible individuals
Immediate actions: Remove any remaining medication from your dog's reach. Note how many chews were consumed and the strength of each. Call your veterinarian or ASPCA Animal Poison Control at (888) 426-4435 immediately. Bring the product packaging to the emergency clinic if directed to go.
Cost, Availability, and Alternatives
Pricing in 2026
NexGard Plus is available only through licensed veterinary pharmacies and your veterinarian's office. Typical retail pricing (6-month supply) in the United States:
- Small dogs (4.5–24 lb): $110–$140 per 6-pack
- Medium dogs (24.1–60 lb): $130–$165 per 6-pack
- Large dogs (60.1–121.5 lb): $150–$190 per 6-pack
Many veterinary clinics offer manufacturer rebates ($15–$25 off a 6-month supply) or bundle discounts when combined with annual wellness exams. Online veterinary pharmacies (Chewy Pharmacy, 1-800-PetMeds, Covetrus) require a valid prescription and may offer slightly lower pricing ($5–$15 savings per 6-pack). As of 2026, there is no generic equivalent of NexGard Plus—the combination formula remains under patent protection.
Comparable Alternatives Your Vet May Consider
| Product | Fleas/Ticks | Heartworm | Intestinal Parasites | Form |
|---|---|---|---|---|
| Simparica Trio | ✅ | ✅ | ✅ (roundworm, hookworm) | Oral chewable |
| Interceptor Plus | ❌ | ✅ | ✅ (+whipworm, tapeworm) | Oral chewable |
| Revolution Plus | ✅ | ✅ | ✅ (roundworm, hookworm) | Topical |
| NexGard + Heartgard Plus (separate) | ✅ | ✅ | ✅ (roundworm, hookworm) | Two oral chews |
When a vet may choose an alternative: If your dog has a seizure history, your veterinarian may recommend a non-isoxazoline flea/tick product (such as a topical like Revolution Plus or Frontline) paired with a standalone heartworm preventive (Interceptor Plus or Heartgard). For dogs with whipworm or tapeworm exposure, Interceptor Plus covers a broader intestinal parasite spectrum than NexGard Plus, though it would need to be paired with a separate flea/tick product.
Frequently Asked Questions
Can I give NexGard Plus to my cat?
No. NexGard Plus is formulated and approved exclusively for dogs. Afoxolaner and pyrantel dosing are species-specific, and the product has not been evaluated for feline safety. For cat parasite prevention, consult your veterinarian about products like Revolution Plus or Bravecto for cats.
Does NexGard Plus protect against tapeworms or whipworms?
No. The pyrantel component covers roundworms and hookworms only. If your dog is at risk for whipworms (common in dogs that frequent soil-heavy environments like dog parks) or tapeworms (common in dogs that hunt rodents or have flea infestations), your veterinarian may recommend a supplemental dewormer such as fenbendazole (Panacur) or praziquantel (Droncit), or switch to a product like Interceptor Plus that includes broader intestinal coverage.
My dog vomited within an hour of taking NexGard Plus. Should I redose?
Contact your veterinarian before redosing. If the full chew was visibly consumed and vomiting occurred more than 30 minutes after administration, sufficient absorption may have occurred. If the chew was partially regurgitated or vomiting happened within minutes, your vet may authorize a replacement dose. Do not redose without veterinary guidance, as duplicate dosing increases the risk of adverse effects.
Is NexGard Plus safe for pregnant or nursing dogs?
The safety of NexGard Plus has not been established in pregnant, breeding, or lactating dogs. The moxidectin and afoxolaner components have not been evaluated in reproductive studies for this specific combination product. If your dog is pregnant or nursing, discuss alternative parasite prevention options with your veterinarian.
Can I buy NexGard Plus without a prescription?
No. NexGard Plus is a prescription-only medication in the United States. Any website or retailer offering it without requiring a valid veterinary prescription is operating outside FDA regulations and may be selling counterfeit, expired, or improperly stored product. Always obtain NexGard Plus through your veterinarian or a licensed veterinary pharmacy that verifies your prescription.
How quickly does NexGard Plus start killing fleas and ticks?
Afoxolaner begins killing fleas within 8 hours of administration and achieves near-complete flea kill within 24 hours. Tick kill begins within 48 hours. For dogs with active flea infestations, you may see increased scratching during the first 12–24 hours as fleas become hyperactive before dying—this is a normal dying-flea reaction, not an allergic response to the medication.
🩺 Veterinary Disclaimer: This article is intended for educational purposes only and does not replace professional veterinary advice. Always consult your veterinarian before starting, stopping, or changing any medication for your dog. Individual dogs may respond differently to any medication based on breed, age, health status, and concurrent conditions. Your veterinarian is the only qualified professional who can determine the appropriate treatment plan for your pet.
Jonas Cole
All our authors care for dogs every day — read more of their work on the authors page.
