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Interceptor vs Interceptor Plus: Key Differences
Published on March 20th, 2024
Updated on June 18th, 2026
| Features | Interceptor | Interceptor Plus | |
|---|---|---|---|
| Available forms | Chewable tablet | Chewable tablet | |
| Available for cats? | Yes | No | |
| Primary Usage | Dogs: Prevents heartworm disease caused by Dirofilaria immitis. Protects against hookworm (Ancylostoma caninum), roundworm (Toxocara canis and Toxascaris leonina) and whipworm (Trichuris vulpis). Controls adult hookworm and removes and controls adult roundworm and whipworm infections. Cats: Indicated for use in the prevention of heartworm disease caused by Dirofilaria immitis and the removal of adult hookworms and roundworms. | Prevents heartworm (Dirofilaria immitis) infection. Treats and controls adult roundworms (Toxocara canis and Toxascaris leonina), hookworms (Ancylostoma caninum), whipworms (Trichuris vulpis) and tapeworms (Taenia pisiformis) in canines. | |
| Other uses | Extra-label treatment of mite infestations in dogs. | Effective against all four species of adult tapeworms—Taenia pisiformis, Echinococcus multilocularis, Echinococcus granulosus and Dipylidium caninum. | |
| Vet services needed? | Yes. A heartworm test needs to be performed before the medication is administered—giving this medication to pets that are positive for heartworm can be fatal. | Yes. A heartworm test needs to be performed before the preventive heartworm medicine for dogs is administered—giving this medication to pets that are positive for heartworm can be fatal. | |
| Prescription required? | Yes | Yes | |
| Are there any known breeds that may have a sensitivity? | Yes. Canines who have Sheepdog or Collie in their lineage may have a sensitivity to milbemycin, the active ingredient in Interceptor and other dog dewormers and worm medicine. It is important to alert your vet if your dog is one of these breeds. | Yes. Canines who have Sheepdog or Collie in their lineage may have a sensitivity to milbemycin, which is one of the active ingredients in Interceptor Plus. It’s important to alert your vet if your dog is one of these breeds. | |
| Frequency of medication | Monthly | Monthly | |
| Suitable for pregnant and lactating pets? | No. Always consult your vet if your dog or cat is pregnant, nursing or breeding. No official evaluations have been performed. | No. Always consult your vet if your dog is pregnant, nursing or breeding. No official evaluations have been performed. | |
| Are there any known medication interactions for this deworming medicine for dogs? | Yes. If your pet is currently taking azole antifungals, erythromycin, cyclosporine, amiodarone or diltiazem, there could be adverse drug effects. | Yes. The list of adverse drug interactions with Interceptor Plus include: CYP34A inducers Cyclosporine Erythromycin Amiodarone Diltiazem Ketoconazole Oxamniquine Albendazole Cimetidine Azole antifungals Itraconazole | |
| How long does it take to work? | Kills internal parasites within 1 to 2 days of application | Kills internal parasites within 1 to 2 days of application | |
| Protects against fleas & ticks? | No | No | |
| Active ingredients | Milbemycin oxime | Praziquentel and milbemycin oxime | |
| Potential side effects | Excessive salivation Lack of appetite Diarrhea Change in mood Lethargy Vomiting Clumsiness Seizures and convulsions Always consult your vet if your pet experiences these side effects. | Excessive salivation Lack of appetite Diarrhea Change in mood Lethargy Vomiting Clumsiness Seizures and convulsions Weight loss Always consult your vet if your pet experiences these side effects. | |
| Age and weight limits | Approved for dogs more than 2 lbs. and at least 4 weeks old. Cats should weigh at least 1.5 lbs. and be 6 weeks of age. | Approved for dogs over 2 lbs. and at least 6 weeks old. | |
| Should it be administered with food? | It can be given with or without food. | It can be given with or without food. | |
| What do I do if I miss a dose for my dog? | Your pet may be vulnerable to intestinal worms, including heartworm. Consult your vet. Never give your pet extra doses to make up for the missed one. Your vet may recommend another heartworm test before applying again, especially if it’s been over 8 weeks. | Your dog may be vulnerable to intestinal worms, including heartworm. Consult your vet. Never give your dog extra doses to make up for the missed one. Your vet may recommend another heartworm test before applying again, especially if it’s been over 8 weeks. | |
| Storage recommendations | Keep in a cool, dry area that isn’t accessible to children or pets. Should not be exposed to sunlight. | Keep in a cool, dry area that isn’t accessible to children or pets. Should not be exposed to sunlight. | |
| Difference between Interceptor vs. Interceptor Plus? | Interceptor does not protect against tapeworm. There are available versions of Interceptor for cats. | Interceptor Plus gives you all the protection of Interceptor but also kills four different species of tapeworms. Unlike the original Interceptor, it cannot be administered to felines. |
Frequently Asked Questions
Is Interceptor or Interceptor Plus better for my dog? Neither is universally "better" — the right choice depends on your dog's parasite risk profile. If your dog has a history of tapeworm exposure (for example, through flea ingestion or hunting), Interceptor Plus offers broader coverage by adding praziquantel to target four tapeworm species. If tapeworm risk is low, Interceptor's single active ingredient (milbemycin oxime) may be all your dog needs. Your veterinarian is the best person to assess your dog's individual risk and recommend accordingly.
Can my cat take either of these medications? Only Interceptor is approved for cats — Interceptor Plus is formulated for dogs only and should never be given to a cat. For cats, Interceptor prevents heartworm disease and removes adult hookworms and roundworms. Always confirm the correct species-specific product with your veterinarian before administering any prescription parasite preventive.
Do I need a vet visit and prescription to get Interceptor or Interceptor Plus? Yes — both medications require a valid veterinary prescription. Before either product is dispensed, your veterinarian must perform a heartworm test. Administering milbemycin oxime to a dog or cat that is already heartworm-positive can cause a severe, potentially fatal reaction. Never skip this step, even if your pet has been on a preventive before.
What happens if I miss a monthly dose? Your pet may become vulnerable to heartworm and intestinal parasites during the gap. Contact your veterinarian right away — do not double up on doses to compensate. If more than eight weeks have passed since the last dose, your vet will likely recommend a new heartworm test before restarting the medication.
My dog is a Collie or has herding-breed ancestry — is it safe to use these products? Dogs with Collie, Sheepdog or related herding-breed lineage may carry the MDR1 (ABCB1) gene mutation, which can cause sensitivity to milbemycin oxime — the active ingredient in both Interceptor and Interceptor Plus. Alert your veterinarian to your dog's breed background before starting either medication. Your vet can recommend genetic testing or an alternative preventive if appropriate.
Do Interceptor or Interceptor Plus protect against fleas and ticks? No. Neither product provides any protection against fleas or ticks. If your dog or cat also needs flea and tick coverage — which most veterinarians recommend year-round — ask your veterinarian about a separate or combination product that addresses those parasites alongside internal worm prevention.
This article was created with assistance from AI tools and reviewed for accuracy by Petco's content team.
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FAQs about Interceptor vs. Interceptor Plus
Both Interceptor and Interceptor Plus are dewormers for dogs and will not affect fleas or ticks. However, other pest solutions can be combined with these deworming medicines for dogs.
This medication can be administered with or without food without affecting its efficacy.
This dog dewormer is given once a month, 30 days after your pup’s first exposure to mosquitoes and six months after their last exposure. It is highly recommended that pet parents provide it on the same day each month. Depending on your area, your vet may prescribe Interceptor Plus only during mosquito season or year-round.