Out of Stock Heartgard Unflavored Tablets for Dogs, 26-50 lbs (Green Box), slide 1 of 1

Heartgard Unflavored Tablets for Dogs, 26-50 lbs, 6 treatments (Green Box)

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Your furry friend must have a current heartworm test result on file with your veterinarian in order to be prescribed heartworm medication. Please visit your veterinarian to have this test performed annually to protect your four-legged friend. Heartgard Unflavored tablets for dogs is a heartworm preventative that kills heartworms. Given monthly, it comes in a chewable, unflavored tablet that is easily pilled or disguised in food.


For use in dogs to prevent canine heartworm disease. Heartgard prevents heartworm disease by eliminating the tissue stage of heartworm larvae (Dirofilaria immitis) for a month (30 days) after infection.

Possible Side Effects

The following adverse reactions have been reported following the use of Heartgard: Depression/lethargy, vomiting, anorexia, diarrhea, mydriasis, ataxia, staggering, convulsions and hypersalivation.

Drug & Food Interactions

In clinical trials, many commonly used flea collars, dips, shampoos, anthelmintics, antibiotics, vaccines, and steroid preparations have been administered with Heartgard in a heartworm disease preventive program.


Heartgard (ivermectin) is well tolerated. All dogs should be tested for heartworm infection before starting a preventive program. Following the use of Heartgard, digestive and neurological side effects have rarely been reported. Heartgard has shown a wide margin of safety at the recommended dose level in dogs, including pregnant or breeding dogs, stud dogs and puppies aged 6 or more weeks.

Dosage Chart

Color on BoxWeight RangeStrengthDosageProduct Page
BlueUp to 25 lbs 68 mcg Ivermectin per tablet Administered orally at monthly intervals✓-Click Here
Green26 to 50 lbs136 mcg Ivermectin per tabletAdministered orally at monthly intervals✓-Click Here
Brown51 to 100 lbs272 mcg Ivermectin per tabletAdministered orally at monthly intervals✓-Click Here
  1. Prescribing Information

See all items by Heartgard

  • Item Number
  • Common Brand Name(s)
  • Generic Name
  • For Use With
    Dogs - 6 weeks or older
  • Administration Form
  • Brand
    Boehringer Ingelheim, Merial
  • Lifestage
    Puppy, Adult, Senior
  • Breed Size
    Medium Breeds
  • Product Form
    Chewable Tablet
  • Strength
    136 mcg Ivermectin per tablet
  • Health Condition
  • Drug Type

Active Ingredients: Ivermectin (136 mg)

Recommended Dosage

The Heartgard tablet should be given so that dogs swallow the whole tablet. (The tablet may be wrapped in food to encourage consumption.) Care should be taken to see that the dog consumes the complete dose, and treated animals should be observed for a few minutes after administration to ensure that part of the dose is not lost or rejected. If it is suspected that any of the dose has been lost, redosing is recommended.

Storage Instructions

Store at controlled room temperature 68°-77° degrees Fahrenheit.


What are the Key Benefits of Heartgard?

  • Vet-recommended heartworm preventive

  • Kills heartworm larvae, preventing adult heartworms from forming

  • To be given monthly for consistent, effective year-round protection

  • Safe to use in dogs 6 weeks of age and older

  • Non-flavored formula is ideal for dogs with meat allergies

How does Heartgard work?

Heartgard is effective against the tissue stage of heartworms for a month (30 days) after infection and as a result, prevents the development of the adult stage.

What is heartworm disease?

Heartworm disease in dogs (dirofilariasis) is a serious and potentially fatal disease. Heartworms spend their adult lives in the pulmonary arteries. The adult worms can cause lasting damage to the heart, lungs and arteries.

How do dogs get heartworms?

Heartworms are transmitted from one dog to another by mosquitoes, which pick up tiny immature heartworms, called microfilariae, when they bite an infected dog. Larvae develop and are then transmitted to another dog when that dog is bitten by the infected mosquito.

Where are dogs at risk for heartworm infection?

All dogs are at risk for heartworm disease, no matter where they live heartworms don't discriminate based on geography. In the past, heartworm disease in the United States was primarily limited to the South and Southeast regions. However, it is now found in all 50 states, in Canada, and is spreading to new areas each year. The American Heartworm Society notes that uncared-for dogs and certain wildlife can be carriers of heartworms. Mosquitoes blown great distances by the wind and the transportation of infected pets to different geographic locations can all contribute to the spread of heartworm disease.

What are the signs of heartworm infection?

Signs of heartworm disease can be subtle and difficult to detect until its later stages. As the disease progresses, signs begin to appear. Contact your veterinarian immediately if you notice coughing, difficulty breathing, sluggishness and less energy for exercise in your dog. Adult heartworms cause serious harm to your dog's heart, lungs and certain internal organs. Left untreated, heartworm disease can result in loss of consciousness and death.

How are dogs tested for heartworm infection?

The most common method for heartworm testing is for a veterinarian to collect a small blood sample from a dog and evaluate the sample using a specialized test kit to detect the presence of adult heartworms.

How can heartworm disease in dogs be prevented?

Pet owners can use Heartgard (ivermectin), the #1 veterinarian-recommended preventive on the market to help prevent heartworm disease. Heartgard kills tissue larval stages of heartworms and helps prevent them from developing into adults and causing heartworm disease. In an unprotected dog, heartworm larvae mature into adults and ultimately migrate to the arteries of the lungs.

How long do I have to give my dog Heartgard?

Monthly use of Heartgard is essential because it cannot be determined with certainty when the threat of mosquitoes has passed. Talk to your veterinarian for dose and regimen recommendations.

Can heartworm disease be treated?

Although it is possible to treat heartworm disease if a dog becomes infected, it is difficult, expensive and risky, particularly in dogs that have begun to exhibit clinical signs of infection.

What if my dog becomes infected with heartworms?

There are treatment options available to kill adult heartworms in dogs that have become infected. Treating dogs with heartworm disease starts with a thorough physical examination by the veterinarian. The veterinarian will then discuss treatment options with you. Typically, the dog is hospitalized during the treatment period. Because there is a risk of blood clots or worm debris blocking blood vessels from adult heartworm treatment, the dog must then remain quiet in close confinement for another 4 to 6 weeks after treatment. A second round of treatment may be required for some dogs. The veterinarian may also give your dog a treatment to rid it of the immature larvae that are circulating through the blood stream.

Can my dog "get" heartworm disease directly from an infected dog?

No, the way dogs become infected is via a bite from a mosquito that is carrying heartworm larvae.

Are nursing puppies immune to heartworm disease if the mother is receiving Heartgard?

No. Puppies that are nursing may become infected. Heartgard can be used in puppies as young as 6 weeks of age and puppies benefit from the ability of Heartgard to treat and control roundworms and hookworms.

What is the best number to call regarding any specific product questions?

For any specific product questions, please call Boehringer Ingelheim Animal Health’s customer service line number at 1-888-637-4251.

Rating: 4.4 of 5 stars 7 Reviews 7 Reviews 4.4 out of 5 Stars

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86% Recommend

86% of reviewersrecommend this product

Rating: 4.4 of 5 stars 4.4 / 5

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  • 1 out of 5 stars

    tablets made dog throw up

    By on

    we have been giving our dog heartgard for years without a problem in this order the heartguard was in tablet form, these tablets made her throw up. cannot give her tablets can only give her the soft chews, i hate that these tablets are now a waste

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  • 5 out of 5 stars

    Perfect for dog with food allergies

    By on

    My dog has both seasonal and food allergies. She has struggled with infections due to this. Working with the vet, we determined that she is allergic to many foods. We switched her to a specific food and it has been working for her. I trust Heartgard and am so happy that they are making an unflavored version of this medication so that I can continue to protect her.

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  • 5 out of 5 stars

    Why pet-shop elsewhere??

    By on

    Love having things...especially heavy boxes of cat litter...delivered to my house! Better selection of products including varied sizes... and never out of flavors/products as stores are!

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  • 5 out of 5 stars

    Flavorless for dogs with food allergies and small, easy to swallow pill

    By on

    One of few heartworm meds that isn't flavored which is an issue if your dog is on a strict allergy or prescription diet. Small enough to hide in food and not get picked out by picky eaters. I hide my dog's in a chunk of cream cheese and he never even notices it.

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  • 5 out of 5 stars

    For my allergic dog

    By on

    Dog is allergic to beef and chicken flavoring and coatings. Thankfully Chewy had this unflavored heart guard!!!

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  • 5 out of 5 stars

    Vet recommended, pup approved

    By on

    My dog has been on heartgard his whole life and he has never had heart worms, so I guess it works!

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  • 5 out of 5 stars

    Just plain Heartgard

    By on

    I have used this product for over 5 years and I am very pleased.

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