5 Best Heartworm Prevention Medications for Dogs in 2026, Recommended by Vets
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Heartworm disease is caused by a parasite spread by mosquito bites that travels through the bloodstream and settles in a dog’s heart and lungs. As the worms grow, they can damage these organs and cause coughing, trouble breathing, fatigue, and, in severe cases, heart failure. The dangers of heartworm disease, the lengthy and complex treatment process, and the high cost of care make heartworm prevention for dogs the safest and most effective defense.
The best heartworm prevention medications for dogs are not only effective but also easy to administer on schedule and appropriate for your pup’s age, weight, and health considerations.
Because heartworm medicine for dogs comes in several forms and contains different active ingredients, our panel of veterinarians selected their choices for the best heartworm prevention for dogs to help simplify your shopping process. Don’t forget to speak with your vet before choosing one—heartworm prevention medication for dogs is available by prescription only, and your vet can help you determine the best option for your pet’s individual needs.
What To Consider When Buying Heartworm Medication for Dogs
When looking at various heartworm preventions for dogs, think about the following factors.
Scope of Coverage
Consider whether you want broad parasite protection or just heartworm prevention. Talk to your veterinarian about which parasites pose the biggest risk to your dog depending on where you live and your dog’s lifestyle. Taking one pill that protects against heartworm disease, fleas, ticks, as well as intestinal parasites may be the right choice for your dog.
Form of Treatment
Heartworm preventives come in several forms, including tablets or chews, and topical treatments. Most are administered monthly. Annual or biannual injectable heartworm medication also exists for dogs. Choose the right one for you and your dog depending on lifestyle and ease of administration.
If your dog doesn’t like tablets or chews or is sensitive to particular flavors or proteins found in some products, then a topical solution may be best. If your dog needs frequent baths, an oral medication may be a better choice, since frequent bathing may reduce the effectiveness of certain topical medications.
Your Dog’s Age, Size, and Health
Dog heartworm medications are safe and effective at the correct dosage, which is determined by your dog’s age and weight. Some drugs, such as those in the isoxazoline class, may not be suitable for dogs with certain health issues, like seizures or neurological disorders.
Your Vet’s Input
Heartworm preventives require a prescription from your vet. Your pup may also need heartworm testing as recommended by your veterinarian; testing requirements and timing depend, in part, on the dog’s age and prevention history.
Aside from these necessary steps, it’s always helpful to discuss with your vet which heartworm medication is appropriate for your individual dog’s unique needs, especially if your pup has a history of seizures, the MDR1 mutation, or sensitivities to certain flavors or proteins.
Honorable Mentions: Best All-in-One Heartworm Prevention for Dogs
Though not included among our panel’s top picks for heartworm prevention for dogs, the experts would also like to recognize two additional all-in-one heartworm medications: Credelio Quattro/Credelio Quattro-CA1 Chewable Tablets for Dogs and NexGard PLUS Chewables for Dogs.
Credelio Quattro Chewable Tablets protect against ticks, fleas, heartworm disease, tapeworms, roundworms, hookworms, and the New World screwworm. Just one monthly chewable kills most fleas within eight hours of administration. The tablet is safe for dogs 8 weeks of age and older, weighing as little as 3.3 pounds or up to 100 pounds. As a member of the isoxazoline class of drugs, it may not be suitable for dogs who have a history of seizures, so be sure to discuss it with your veterinarian.
NexGard PLUS Chewables come in soft, beef-flavored chews given monthly to protect against fleas, ticks, heartworm disease, roundworms, and hookworms. It’s safe for dogs 8 weeks of age and older, weighing as little as 4 pounds or up to 132 pounds. As a member of the isoxazoline class of drugs, it may not be suitable for dogs who have a history of seizures, so be sure to discuss it with your veterinarian.
If you’re looking for an affordable option, our veterinary panel also likes Iverhart Max Chew for Dogs. The bacon-flavored monthly chew prevents heartworm disease and treats and controls roundworms, hookworms, and tapeworms.
How We Selected the Best Heartworm Prevention Medication for Dogs
This list of the best heartworm medications for dogs in 2026 was meticulously curated by a panel of veterinarians who are employed by Chewy, the publisher of PetMD. They were asked to choose the best heartworm medications for dogs in their honest opinion, across multiple categories, based on the following:
- Efficacy
- Ease of administration
- Spectrum of protection
- Cost and availability
Opinions and product recommendations in this article belong solely to the review panel of vets. Manufacturers and vendors cannot buy placement in Vet Verified content or exert influence on our panelists as they evaluate products.
Our sole goal with this program is to provide pet parents with the information they need to make the best decision for their pets.
Heartworm Prevention Medication for Dogs FAQs
Do dogs really need heartworm prevention?
Yes. Giving your dog a heartworm prevention year-round is important because heartworm disease is a serious mosquito-borne disease, and transmission can be difficult to predict. Heartworm disease has been diagnosed in dogs in every U.S. state, and the American Heartworm Society recommends year-round prevention.
Can I buy heartworm prevention over the counter?
No, heartworm prevention medicine can’t be bought over the counter; it is available by prescription from a veterinarian. Your veterinarian will consider your dog’s age, weight, health, and needs when recommending a preventive. Depending on your dog’s age and history with heartworm preventives, testing for active heartworm disease is also often recommended before treatment, but your vet will advise what’s best for your pup.
What is the safest heartworm prevention for dogs?
The safest heartworm prevention for your dog depends on factors such as their weight, age, health history, and individual needs. FDA-approved heartworm preventives are available by prescription from a veterinarian. Popular vet-recommended options include Interceptor Plus Chew, Advantage Multi Topical Solution, and Heartgard Plus Chew. Your veterinarian can recommend the most appropriate option for your particular dog.