Trifexis vs spinosad + milbemycin for Dogs
Trifexis is the brand name for spinosad + milbemycin, prescribed for fleas + heartworm + intestinal worms in dogs. Generic spinosad + milbemycin typically costs ~$36 at Script Unlock pharmacies vs $92 for brand at the vet — savings of ~$56 per fill.
Brand vs Generic — real pricing
Typical monthly pricing for a 30-day supply.
Prices are averages from recent Script Unlock pharmacy bids. Actual bid ranges vary by pharmacy, location, and quantity. Upload your vet's Rx to see live bids for your ZIP.
Are generics safe for dogs?
Yes. FDA-approved generic pet medications must demonstrate bioequivalence to the brand — meaning the same active ingredient reaches the same blood concentration in the same time frame. Clinical effect is expected to be identical.
The only differences between brand Trifexis and generic spinosad + milbemycin are:
- Manufacturer — different companies produce brand vs generic
- Packaging + inactive ingredients — different fillers, dyes, coatings (all FDA-approved)
- Price — typically 30-60% lower for the generic
A very small percentage of individual pets respond differently to generic vs brand — usually because of inactive ingredient sensitivity, not the active drug. If you notice any change in your dog's response after switching, consult your vet.
How to get generic spinosad + milbemycin for your dog
Ask your vet at the next visit
Say: "Please write my dog's Trifexis prescription so it allows generic substitution." Most vets do this by default; a small number specifically write brand-only for clinical reasons.
Upload the Rx to Script Unlock
Photo or PDF at /upload-prescription. Note in the details field: "Generic acceptable" — pharmacies will bid on the generic if the Rx allows substitution.
Compare bids in 1-4 hours
Verified pharmacies submit competitive cash prices. Some bid brand, some bid generic — you see both and choose. Winning bids typically save 45-65% vs vet office.
Monitor closely on the first switch
Watch for any change in response for 2 weeks after switching from brand to generic. Rare individual pets are sensitive to inactive ingredients — contact your vet immediately if you notice anything unusual.
Frequently asked questions
Is spinosad + milbemycin the same as Trifexis?↓
spinosad + milbemycin is the FDA-approved generic version of Trifexis. Same active ingredient, same clinical effect, same dosing. The difference is manufacturer, packaging, and price. Generic versions of pet medications are FDA-regulated to be bioequivalent to the brand.
How much cheaper is generic spinosad + milbemycin vs brand Trifexis?↓
Generic spinosad + milbemycin typically costs ~$36 at Script Unlock pharmacies vs $65 for brand Trifexis — savings around $29 per fill (~45%). For chronic prescriptions that's hundreds of dollars per year.
Will my vet write a prescription for generic spinosad + milbemycin?↓
Yes — most vets will write a prescription that allows generic substitution. Ask specifically: "Please write this for generic spinosad + milbemycin so I can compare pharmacy prices." Some vets specifically write brand-only prescriptions if there's a clinical reason.
Is generic spinosad + milbemycin as effective as brand Trifexis for dogs?↓
FDA-approved generics for pet medications must demonstrate bioequivalence — the active ingredient reaches the same concentration in the same time as brand. Clinical effect is expected to be identical. Rare individual pets may respond differently — discuss with your vet before switching.
Find the lowest your pet's trifexis cash price
Upload your your pet's trifexis prescription and verified pharmacies bid for your fill. 100% free for patients. No insurance, no membership, no sign-up.
Free for patients. No insurance, no membership, no sign-up required.