Heartworm prevention is one of the most important medications for your dog. Heartworm disease is fatal if untreated, and treatment costs $600–$6,000 — while prevention costs just $30–$120/month. All heartworm medications require a veterinary prescription and a negative heartworm test before starting.
The average cost of dog heartworm medication is $60 per month, with most owners paying between $30 and $120 per month depending on the brand and whether it's combined with flea/tick prevention.
Heartworm Medication Cost by Brand
| Brand | Monthly Cost | Annual Cost | Covers |
|---|---|---|---|
| Heartgard Plus | $30–$50 | $360–$600 | Heartworm + roundworms + hookworms |
| Tri-Heart Plus | $25–$40 | $300–$480 | Heartworm + roundworms + hookworms (generic Heartgard) |
| Interceptor Plus | $35–$55 | $420–$660 | Heartworm + tapeworms + roundworms + hookworms + whipworms |
| Sentinel | $40–$60 | $480–$720 | Heartworm + fleas (prevents eggs, doesn't kill adults) |
| Trifexis | $50–$80 | $600–$960 | Heartworm + fleas + intestinal worms (combo) |
| Simparica Trio | $55–$90 | $660–$1,080 | Heartworm + fleas + ticks + intestinal worms (combo) |
| Revolution (topical) | $50–$75 | $600–$900 | Heartworm + fleas + ear mites + sarcoptic mange |
| Advantage Multi (topical) | $45–$70 | $540–$840 | Heartworm + fleas + intestinal worms |
Cost by Dog Weight
| Dog Weight | Heartgard Plus | Simparica Trio | Trifexis |
|---|---|---|---|
| Under 25 lbs | $35–$45/mo | $50–$65/mo | $50–$65/mo |
| 26–50 lbs | $40–$50/mo | $60–$75/mo | $55–$70/mo |
| 51–100 lbs | $45–$55/mo | $70–$85/mo | $65–$80/mo |
| Over 100 lbs | $50–$60/mo | $80–$100/mo | $75–$90/mo |
Heartworm Prevention vs. Treatment Cost
| Option | Cost | Duration | Outcome |
|---|---|---|---|
| Prevention (monthly medication) | $360–$1,080/year | Lifelong monthly | Prevents infection — 99% effective |
| Heartworm treatment (already infected) | $600–$6,000 | 3–6 months of treatment | Kills adult worms — painful, risky, expensive |
| 5-year cost comparison | $1,800–$5,400 (prevention) | vs. $600–$6,000 (one treatment) | Prevention is cheaper and safer |
Where to Buy Heartworm Medication
| Source | Price vs. Vet | Notes |
|---|---|---|
| Vet clinic | Baseline (most expensive) | Convenient but 50–100% more than online |
| Chewy.com | 30–40% cheaper | Auto-ship saves 35%; needs Rx from vet |
| 1-800-PetMeds | 25–35% cheaper | Price match guarantee; needs Rx |
| Petco/Petsmart | 20–30% cheaper | In-store pickup; needs Rx |
| Costco Pharmacy | Variable — check pricing | Some brands available; need Rx |
Frequently Asked Questions
How much does dog heartworm medication cost?
Dog heartworm medication costs $30 to $120 per month, with an average of $60. Heartgard Plus costs $30–$50/month. Simparica Trio (heartworm + flea + tick combo) costs $55–$90/month. Annual cost is $360–$1,080. Combo products that also cover fleas and ticks cost more but save money vs. buying separate medications.
Does pet insurance cover heartworm medication?
Most standard pet insurance doesn't cover preventive medications like heartworm prevention — these are considered routine care. However, wellness add-on plans or preventive care packages often cover heartworm medication. Treatment for heartworm disease (if your dog gets infected despite prevention) is covered under illness coverage.
Do I need a heartworm test before starting medication?
Yes. Your dog must test negative for heartworms before starting prevention medication. Giving heartworm prevention to an infected dog can cause a dangerous reaction. Annual heartworm testing ($25–$50) is required even if your dog is consistently on medication.
What's the cheapest heartworm medication for dogs?
Tri-Heart Plus ($25–$40/month) is the cheapest branded option — it's a generic equivalent of Heartgard Plus. For combo coverage (heartworm + fleas + ticks), Simparica Trio is popular but costs $55–$90/month. Buying online with auto-ship from Chewy saves 30–35% vs. buying at the vet.