Interceptor Plus vs Heartgard Plus – Which Parasite Preventive Is Better?

Interceptor Plus vs Heartgard Plus – Which Parasite Preventive Is Better?

Edward Simmons

Is your dog truly protected from all major parasites—or just heartworms?

Most heartworm medications don’t protect against intestinal parasites like tapeworms or whipworms. Choose a preventive medication that matches your dog’s breed, age, and health profile to ensure full-spectrum protection.

📌 TL;DR: Interceptor Plus vs. Heartgard Plus for Dog Parasite Protection

  • Interceptor Plus protects against 5 parasites: heartworms, roundworms, hookworms, whipworms, and tapeworms. It's safer for herding breeds and ideal for dogs needing broad-spectrum coverage.
  • Heartgard Plus protects against 3 parasites: heartworms, roundworms, and hookworms. It's more budget-friendly but lacks whipworm and tapeworm protection.
  • Both are monthly chewables, FDA-approved, and require a vet prescription.
  • Switching between medications is safe with vet guidance and proper timing.
  • Buy from HardyPaw.com for verified, prescription-based medications with flexible auto-ship options.

Choosing the right heartworm preventive is more than just following a vet’s prescription; it's about understanding the broader spectrum of parasites, the active ingredients involved, and how they interact with your dog’s breed, age, and health conditions. 

Did you know that every three years, the American Heartworm Society (AHS) surveys veterinary clinics and consistently finds that the number of dogs testing positive for heartworm increases by more than 50,000 with each survey cycle? [source]

Two of the most widely prescribed options: Interceptor Plus and Heartgard Plus - offer protection against heartworms, roundworms, and hookworms, but differ significantly when it comes to whipworm and tapeworm coverage, flavor profiles, and breed safety, particularly for herding breeds like Collies and Australian Shepherds.

In this guide, we’ll break down how these medications compare in terms of parasite coverage, ingredient efficacy, side effects, and real-world suitability for your dog’s unique needs

You’ll also learn:

  • What makes a heartworm medication truly veterinarian-approved?
  • How to safely switch between preventives, and
  • Where to find trusted, prescription-based pet medications online to make the most informed, personalized choice for your dog’s long-term health?

So, without any further ado, let’s start!!!

What Is Interceptor Plus?

Interceptor Plus protects dogs from five types of parasites using milbemycin oxime and praziquantel. It eliminates heartworms, roundworms, hookworms, whipworms, and tapeworms in one monthly chew.

It’s ideal for pet owners who want to protect their dog from more than just heartworms with a single, easy-to-administer treatment.

What are the active ingredients in Interceptor Plus?

Interceptor Plus contains two powerful active ingredients:

  • Milbemycin oxime: eliminates heartworm larvae, roundworms, hookworms, and whipworms.
  • Praziquantel: specifically targets and removes tapeworms.
    This combination ensures that your dog is protected from both circulatory and intestinal parasites with a single dose.

What parasites does Interceptor Plus protect against?

Interceptor Plus offers 5-in-1 parasite protection. It defends your dog from:

  • Heartworms
  • Roundworms
  • Hookworms
  • Whipworms
  • Tapeworms

This wide spectrum of coverage makes it a go-to choice for households looking to minimize exposure to parasitic infections—especially in multi-dog homes or areas with high parasite risk.

When can I start Interceptor Plus for my dog?

Dogs as young as 6 weeks old and weighing at least 2 pounds can start on Interceptor Plus. It’s one of the few medications suitable for puppies early in life, making it an excellent option for establishing lifelong parasite prevention.

What form does Interceptor Plus come in, and how often is it given?

Interceptor Plus is a chicken-flavored chewable tabletonce a month. Its taste appeals to most dogs, and the chewable format makes it easy for pet parents to administer without the stress of pills or messy applications. Regular monthly dosing ensures continuous protection without interruption.

Does Interceptor Plus have side effects or breed restrictions?

Interceptor Plus may cause mild side effects like vomiting, diarrhea, or lethargy. These effects are rare and typically occur during early doses.

For owners of herding breeds like Collies or Australian Shepherds, Interceptor Plus is a safer alternative to ivermectin-based medications because it does not carry the same neurological risk associated with the MDR1 gene mutation.

How much does Interceptor Plus cost, and is it worth it?

The cost of Interceptor Plus varies between $11 to $14 based on the dog’s weight and age.

Here is the complete breakdown of Interceptor Plus pricing available at HardyPaw:

[Note: Actual pricing may vary over time. Please check the product page for the most up-to-date pricing information.]

Compared to basic heartworm meds, Interceptor Plus delivers greater value through its broad parasite protection, tailored by weight for affordability and effectiveness.

Now that we’ve covered everything you need to know about Interceptor Plus; let’s explore how Heartgard Plus differs from Interceptor Plus.

What Is Heartgard Plus?

Heartgard Plus is a trusted, vet-recommended medication used by millions of dog owners to maintain monthly parasite protection. It’s known for its ease of use, high palatability, and targeted approach to common internal threats.

With flavor dogs enjoy and a safety profile approved for early-age use, Heartgard Plus helps pet owners stay consistent with prevention—without the stress of forced dosing or complex routines.

What are the active ingredients in Heartgard Plus?

The medication features a dual-ingredient formula that addresses parasites frequently found in domestic dogs. It includes:

  • Ivermectin: targets and prevents heartworm larvae from maturing in the bloodstream.
  • Pyrantel pamoate: controls roundworms and hookworms, which are common in puppies and adult dogs.

While it doesn’t protect against tapeworms or whipworms, its simplicity and focused coverage make it a popular, lower-cost option for many pet parents.

What parasites does Heartgard Plus protect against?

Heartgard Plus protects dogs from:

  • Heartworms
  • Roundworms
  • Hookworms

If your dog is at lower risk for other types of parasites or if you’re primarily concerned with heartworm prevention, Heartgard Plus may be a sufficient and effective choice.

At what age can dogs start using Heartgard Plus?

Dogs can start Heartgard Plus at six weeks, making it suitable for young puppies entering a routine prevention program. However, there is no minimum weight requirement, which offers more flexibility for small breeds.

What form does Heartgard Plus come in, and how is it given?

Heartgard Plus is available as a beef-flavored chewable which needs to be administered once per month. Most dogs find it palatable and treat-like, which makes it easy for owners to maintain regular dosing without stress or resistance.

Does Heartgard Plus have side effects or breed considerations?

Side effects of Heartgard Plus are rare but may include digestive upset such as vomiting or diarrhea. Pet parents with herding breeds (like Collies, Australian Shepherds, and Shelties) should be cautious. Because Heartgard Plus contains ivermectin, dogs with the MDR1 gene mutation may be at risk for neurological side effects if overdosed. A vet can advise whether genetic testing or an alternative medication is appropriate.

How much does Heartgard Plus cost 

The cost of Heartgard Plus varies between $11 to $15 based on the dog’s weight and age.

[Note: Actual pricing may vary over time. Please check the product page for the most up-to-date pricing information.]

Heartgard Plus is a cost-effective option for dog owners seeking essential parasite protection without additional features. It offers flexible pricing based on your dog’s size.

Now that we’ve reviewed what Interceptor Plus and Heartgard Plus offer individually, let’s directly compare them side by side to see which one fits your dog’s lifestyle, breed, and health needs best.

What is the difference between Interceptor Plus and Heartgard Plus?

The main difference between Interceptor Plus and Heartgard Plus is parasite coverage. Interceptor Plus protects against heartworms, roundworms, hookworms, whipworms, and tapeworms. Heartgard Plus protects only against heartworms, roundworms, and hookworms. Interceptor Plus is also safer for herding breeds due to its ivermectin-free formula.

Interceptor Plus vs. Heartgard Plus - Side-by-Side Comparison

With a clear view of how these two preventatives stack up side by side, let’s now look at what’s involved in transitioning from one medication to the other - a step that requires careful timing and veterinary guidance.

Transitioning Between Heartworm Medications

Learn how to safely transition between Interceptor Plus and Heartgard Plus without compromising your dog’s protection.

Can I switch from Heartgard Plus to Interceptor Plus?

Yes, you can switch from Heartgard Plus to Interceptor Plus, especially if your dog needs broader parasite protection or belongs to a herding breed sensitive to ivermectin. Interceptor Plus is often chosen when tapeworm and whipworm coverage is desired or when a vet recommends avoiding ivermectin-based treatments.

How do I switch from Heartgard Plus to Interceptor Plus?

To transition safely:

  • Wait until the next scheduled dose of Heartgard Plus before administering Interceptor Plus—do not overlap treatments unless directed by your veterinarian.
  • If you’ve missed a dose or delayed more than 30 days, your vet may recommend a heartworm test before restarting protection.
  • Monitor your dog after the first dose for mild side effects like digestive upset.

This switch provides a more comprehensive protection spectrum, especially for dogs exposed to high-risk environments like dog parks, kennels, or rural areas.

Is it safe to go from Interceptor Plus to Heartgard Plus?

Switching from Interceptor Plus to Heartgard Plus is possible, particularly for dogs who do well with simpler parasite coverage or if you're managing budget constraints. However, you should ensure your dog is not at increased risk for tapeworms, or whipworms, since Heartgard Plus does not cover those.

How do I switch from Interceptor Plus to Heartgard Plus?

To switch:

  • Ensure your dog is still within the monthly coverage window of their last Interceptor Plus dose.
  • Administer Heartgard Plus at the next scheduled time without overlapping.
  • Consult your veterinarian to ensure this shift is safe, especially if your dog has had intestinal parasites previously treated by Interceptor plus.

Remember: this switch narrows the protection spectrum, so it's best suited for dogs with low environmental exposure risk and no prior issues with whipworms or tapeworms.

General Guidelines for a Safe Transition

  • Always consult your veterinarian before switching medications. They can recommend the safest timing and confirm your dog’s protection won’t lapse.
  • Never give two heartworm preventatives simultaneously unless your vet advises it.
  • Keep track of your dog’s last dosage date to maintain a consistent 30-day interval between treatments.

Do I need a heartworm test before switching between Heartworm Medications?

If your dog has missed a dose or there’s been a gap longer than 30 days between treatments, your vet may recommend a heartworm blood test. This ensures it's safe to start or restart treatment—preventing complications from administering medication to an infected dog.

Why veterinary consultation is essential?

Switching heartworm medications without guidance can lead to gaps in protection or adverse reactions, particularly in dogs with breed-specific sensitivities. Your vet knows your dog’s health history and can help you make the best choice based on their risk factors, lifestyle, and regional parasite exposure.

Where can I buy Interceptor Plus or Heartgard Plus?

Both Interceptor Plus and Heartgard Plus are prescription-only medications and can be conveniently purchased at HardyPaw.com. With an active vet prescription, you can:

  • Select your dog’s correct weight range
  • Upload or authorize prescription verification
  • Enjoy fast, trusted shipping and competitive per-dose pricing

This ensures you're getting authentic, veterinarian-approved protection with zero risk of counterfeit or expired products—unlike generic listings on third-party platforms.

Why order from HardyPaw instead of a general retailer?

  • Vet-authorized products only – No over-the-counter confusion or substandard generics.
  • Transparent pricing by dog size – Know exactly what you're paying per chew.
  • Dosing support for every weight category – From 2 lbs to 100 lbs.
  • Pet-owner-friendly service – Helpful customer support and reorder reminders.

HardyPaw focuses exclusively on clinical-grade parasite control, making it a safer, more specialized choice for proactive pet parents.

Can I set up auto-shipping for monthly doses?

Absolutely. HardyPaw offers auto-refill and subscription options for many heartworm medications. This ensures your dog never misses a dose and gives you peace of mind with timely, uninterrupted protection.

Interceptor Plus Or Heartgard Plus - Which is Better Heartworm Preventative for Dogs?

When it comes to protecting your dog from internal parasites, both Interceptor Plus and Heartgard Plus are trusted, vet-approved options—but they’re not interchangeable.

  • Choose Interceptor Plus if you want broader parasite protection, including tapeworms and whipworms, or have a herding breed.
  • Opt for Heartgard Plus if your dog only needs core protection and you prefer a lower-cost option.

Either way, monthly prevention is non-negotiable when it comes to your dog’s health.

Interceptor Plus vs Heartgard Plus FAQs

Can I give Interceptor Plus with other parasite preventives like flea or tick treatments?

You can give Interceptor Plus with flea and tick medications if active ingredients do not interact. Vets confirm compatibility based on ingredient profiles and breed safety.

How long does it take for Interceptor Plus or Heartgard Plus to start working?

Both start killing parasites within hours. Heartworm prevention begins within 24 hours, while intestinal worms start dying in 4–8 hours post-dose.

Should I give my dog heartworm medicine all year?

Yes. Vets recommend year-round heartworm prevention because mosquitoes—and the risk of infection—can persist even during cooler months.

Can my dog develop resistance to heartworm medication over time?

Parasite resistance is rare but possible with missed doses or improper use. Annual testing ensures the medication remains effective.

Can I buy heartworm prevention without seeing a vet?

No. By law, a veterinarian must prescribe heartworm medication after a negative test to ensure safe and appropriate use.

What signs show the heartworm medication is working properly?

Lack of symptoms like coughing or weight loss and a negative annual heartworm test confirm the medication is working as intended.

Are there natural alternatives to heartworm prevention?

No natural treatments are clinically proven to prevent heartworm disease. Only FDA-approved medications are considered safe and effective.

Medical References Used:

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