Interceptor vs ProHeart: what's the difference?
How Interceptor and ProHeart compare: what each is for, how it works, side effects and cost, side by side.
Last updated: October 2026 · 3 sources · see sources
Side by side
| Interceptor | ProHeart | |
|---|---|---|
| Generic name | Milbemycin oxime | Moxidectin (injectable) |
| Brand names | Interceptor, Sentinel, Trifexis | ProHeart 6, ProHeart 12 |
| For | Dogs and cats | Dogs |
| Prescription | Prescription | Prescription, given at the clinic |
| Used for | Prevents heartworm and treats hookworms and roundworms. Some combinations also control fleas. [1] | An injection that prevents heartworm for 6 or 12 months and treats hookworms. [2] |
| How it works | It kills heartworm larvae and some intestinal worms by acting on their nerves. [1] | It kills heartworm larvae, and the shot slowly releases the drug over months. [2] |
| Common side effects | Well tolerated at regular doses. Higher doses can cause weakness, wobbliness and drooling. [1] | Injection-site irritation, mild vomiting or diarrhea, drooling and low energy. Serious allergic reactions are rare. [2] |
| Use with care | Dogs need a negative heartworm test before starting. [1] | Not for sick, frail or underweight dogs. Age minimums differ for the 6- and 12-month versions. [2] |
| Typical price | Monthly heartworm preventive, as listed on owner bills: $6–$18 a dose [3] | No reliable published price |
| Full guide | Interceptor guide | ProHeart guide |
Key differences
- They aren't made for the same animals: Interceptor is for dogs and cats; ProHeart is for dogs.
- How you get them differs: Interceptor is prescription; ProHeart is prescription, given at the clinic.
- A clinic-given medicine means a trip to the vet each time, which adds visit fees but takes the daily pill off your plate.
Which one is right for my pet?
That is a call for your vet. They weigh your pet's age, weight, other health problems, other medicines and what you can realistically give at home.
Switching from Interceptor to ProHeart is common, but do it only with your vet's plan.
Common questions
What is the difference between Interceptor and ProHeart?
Interceptor is given at home and also treats hookworms and roundworms; ProHeart is a clinic injection that lasts 6 or 12 months.
Is Interceptor better than ProHeart?
Neither is better for every pet. Your vet chooses based on your pet's species, age, health history, other medicines and what you can manage at home.
Can my pet take Interceptor and ProHeart together?
Only if your vet says so. Some medicines in the same family should not be combined, and others are often used together. Always check before adding or switching.
Do Interceptor and ProHeart need a prescription?
Interceptor: Yes. It needs a prescription from a veterinarian. ProHeart: Yes. It's prescription-only and is usually given at the vet clinic.
How much do Interceptor and ProHeart cost?
Interceptor: Monthly heartworm preventive, as listed on owner bills $6–$18 a dose. ProHeart: no reliable published price. Prices vary by pet size, pharmacy and clinic.
Related
This page is general information for planning, not veterinary advice. Talk to your vet about your own pet.