Selamectin
Semi-synthetic avermectin
Also known as: Revolution · Selehold · Stronghold Plus · UK-124114 · Selamectina · Selamectinum
Reviewed by the VetSheet Veterinary TeamUpdated Apr 5, 2026Evidence-based veterinary reference
Audited v13 dosing evidence
Structured calculator evidenceBiting lice (extra-label)
Verified clinician required
- once
NA
Governing clinical context (1)
- The commercially available solution should be stored below 30°C (86°F). Keep away from flame or other igniters.
Doses are a clinical reference for licensed veterinary professionals. Always confirm against the current label and the individual patient.
Overview
Selamectin is a broad-spectrum, semi-synthetic avermectin topical parasiticide used extensively in veterinary medicine.
Key Clinical Features:
- Broad Spectrum: Effective against a wide range of internal and external parasites, including heartworm larvae, fleas, ear mites, sarcoptic mange, and certain ticks.
- Feline Intestinal Parasites: In cats, it is also effective against hookworms and roundworms.
- Safety Profile: Highly safe, even in avermectin-sensitive breeds (e.g., Collies with the MDR1 mutation) when used at the recommended topical label doses.
- Systemic Absorption: Unlike many topical flea/tick products that remain in the lipid layer of the skin, selamectin is absorbed systemically, which is necessary for its efficacy against heartworm and internal parasites.
Mechanism of action
Selamectin acts by binding to glutamate-gated chloride channels in the nervous system of invertebrates.
Binding → increased permeability of the cell membrane to chloride ions → hyperpolarization of the nerve or muscle cell → flaccid paralysis and death of the parasite.
Clinical Pearl: Mammals generally lack glutamate-gated chloride channels, and macrocyclic lactones do not readily cross the intact mammalian blood-brain barrier (mediated by P-glycoprotein), conferring a high margin of safety.
Safety & warnings
Contraindications
- Application to broken skin
- Application to wet hair coats
- Use in severely debilitated or underweight animals (relative)
- Puppies and kittens under 6 weeks of age
- Sick, debilitated, or severely underweight animals
- Known hypersensitivity to the active substance or excipients
Adverse effects
- Transient localized alopecia at application site (rare)
- Mild, transient gastrointestinal signs (vomiting, diarrhea) if ingested
- Transient local alopecia at the application site
- Application site irritation or pruritus
- Rarely: vomiting, diarrhea, lethargy, or anorexia
- Rarely: neurological signs (tremors, ataxia) in highly sensitive individuals
Precautions
Do not massage into skin. Do not apply if hair coat is wet. Because the product contains alcohol, do not apply to broken skin. The product is flammable; keep away from flame or other igniters.
Drug interactions
Potential for additive toxicity, though selamectin has a high margin of safety.
May theoretically increase systemic absorption and CNS penetration, increasing the risk of toxicity.
Monitoring
- Clinical efficacy
- Owner compliance with treatment regimen
- Efficacy of parasite control
- Application site for signs of irritation or alopecia
Pharmacokinetics
Half-life
Absorption
Absorbed systemically through the skin. Maximum plasma concentrations are reached in about 72 hours in dogs and 15 hours in cats.
Distribution
Distributes widely and concentrates in the sebaceous glands, which act as a reservoir for prolonged topical efficacy.
Metabolism
Undergoes some hepatic metabolism.
Elimination
Excreted primarily in the feces, with a small amount in the urine.
Overdose
Generally very safe. Overdoses up to 10 times the recommended dose typically do not produce clinical signs in dogs or cats. If massive accidental ingestion occurs, monitor for neurologic signs (ataxia, tremors, mydriasis) and provide supportive care.
Available products
Formulations
- Topical solution
- Topical spot-on solution (6% w/v)
- Topical spot-on solution (12% w/v)
- Topical spot-on solution combined with sarolaner (Stronghold Plus)
Veterinary
- Selamectin Topical Solution for Cats; Revolution (Pfizer): 15 mg/tube (mauve), 45 mg/tube (blue)
- Selamectin Topical Solution for Dogs; Revolution (Pfizer): 15 mg/tube (mauve), 30 mg/tube (purple), 60 mg/tube (brown), 120 mg/tube (red), 240 mg/tube (teal)
- Selehold spot-on solution (6%, 12%)
- Stronghold spot-on solution (6%, 12%)
- Stronghold Plus spot-on solution (selamectin + sarolaner)
Human-labeled
- None
Regulatory status
Classified as POM-V.
Classified as POM-V.
No regulatory data for: 🇺🇸 US · 🇭🇰 HK · 🇹🇼 TW · 🇯🇵 JP · 🇰🇷 KR · 🇦🇺 AU
Storage & stability
Store below 30°C (86°F). Keep away from flame or other igniters.
Client information
Important Application Instructions:
- Apply directly to the skin at the base of the neck in front of the shoulder blades.
- Do not massage the liquid into the skin.
- Do not apply if the pet's hair coat is wet.
- Wait at least two hours after applying before bathing your pet or allowing them to swim.
Safety Warnings:
- Avoid contact with the application site until it is completely dry.
- Avoid getting the product on your own skin; if contact occurs, wash off immediately with soap and water.
- Flammable: Keep the product away from open flames or heat sources.
VetSheet drug reference is intended for licensed veterinary professionals as a clinical decision-support aid, not a substitute for professional judgement or the manufacturer’s current label.