Spinosad

What is this medication for?

• Flea (Ctenocephalides felis) treatment + 1-month prevention, dogs ≥14 weeks
• Not labeled/effective for ticks (pilot data at 1.7–3.3× doses only partial)

How is it given?

Give exactly as your veterinarian prescribed — never change the dose or stop on your own unless your veterinarian has told you to.

• Monthly WITH FOOD is the compliance script — empty-stomach dosing = vomiting = missed month.

What if I miss a dose?

• Give it as soon as you remember — unless it is almost time for the next dose (then skip the missed one; never double up).
• Call your clinic if you miss more than one dose in a row.

Side effects — what should I watch for?

Effects listed as common in this handout

• Vomiting (Most common — mitigated by giving with food)
• Lethargy, loss of appetite, diarrhea (Occasional label events)
• Ivermectin sensitivity note (MDR1) (Spinosad + high-dose ivermectin interaction caused tremors in some dogs — space spinosad and extra-label high-dose ivermectin apart; standard HW-preventive doses fine)

Worth a phone call to your veterinarian

• Any new symptom that worries you.

⚠️ Contact your veterinarian or an emergency clinic IMMEDIATELY if you notice

• Trouble breathing, collapse, seizures, severe vomiting or diarrhea, facial swelling, or pale gums

Before starting (or refilling), tell your veterinarian if your pet:

• has or has had: <14 weeks old; dogs on extra-label high-dose ivermectin (demodex protocols) — separate administrations

• is pregnant, nursing, or used for breeding
• is taking any other medications, supplements, or flea/tick products, including:
  • High-dose ivermectin (extra-label)
  • Milbemycin (Trifexis combo)

Storage and handling

Monthly chewable; beef-flavored. The +milbemycin combination (Trifexis) adds heartworm prevention — test HW-negative first.

Good to know

• The FDA-vs-EPA distinction matters in pharmacy law: Comfortis is a drug (FDA, oral, prescription), most topicals are pesticides (EPA) — different labeling, dispensing, and adverse-event reporting worlds.
• Monthly WITH FOOD is the compliance script — empty-stomach dosing = vomiting = missed month.
• Systemic oral = swims/baths don't dilute efficacy — the practical edge over fipronil/imidacloprid topicals.
• Kills adults before eggs → environmental decontamination still needed for established infestations (none of the adulticides fix the carpet).