Selamectin

What is this medication for?

• Flea control, heartworm prevention, ear mites, sarcoptic mange, tick control (Dermacentor variabilis)
• Flea control, heartworm prevention, ear mites, hookworms (A. tubaeforme), roundworms (T. cati)

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.

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

• Transient localized alopecia at application site (~1% of cats)
• Diarrhea, vomiting, muscle tremors, loss of appetite, itching/hives, erythema, low energy/tiredness, salivation, tachypnea (≤0.5% incidence)

Worth a phone call to your veterinarian

• Any new symptom that worries you.

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

• Seizures, wobbliness/unsteadiness (very rare) (Rare)

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

• has or has had: Not recommended <6 weeks (dog) or <8 weeks (cat) of age
• has or has had: Use caution in sick/underweight/debilitated animals; ABCB1-mutant breeds should tolerate labeled dose but use cautiously — higher doses may cause neurotoxicity

• is pregnant, nursing, or used for breeding
• is taking any other medications, supplements, or flea/tick products, including:
  • P-glycoprotein inhibitors (azoles, cyclosporine, diltiazem, macrolide antibiotics, quinidine, spironolactone, amiodarone, tamoxifen, verapamil, carvedilol)

Storage and handling

Store below 30°C, protect from flame (contains flammable alcohol vehicle).

Good to know

• Not effective against adult heartworms or clearing circulating microfilaria — label explicitly states this; don't rely on it as sole therapy in a heartworm-positive patient.
• Application technique matters: do not massage into skin, do not apply to wet coat, avoid contact with treated area until dry, wait ≥2h before bathing/swimming.
• Not effective for generalized demodicosis — despite being in the same drug class as ivermectin/milbemycin, selamectin has not shown efficacy for this indication.