Pet Safety / Compounds / Allethrin

Is Allethrin safe for dogs and cats?

Low risk for pets

Dogs are tolerant of allethrin at typical mosquito coil and vaporizer use concentrations; the main precaution is ensuring adequate room ventilation when using coil products overnight. Direct ingestion of a mosquito coil (a dog chewing on an unlit coil) may cause mild GI signs from the allethrin and inert ingredients (corn starch binder) but systemic pyrethroid toxicity is unlikely at the small amount in one coil.

What is allethrin?

The IUPAC name is (2-methyl-4-oxo-3-prop-2-enylcyclopent-2-en-1-yl) 2,2-dimethyl-3-(2-methylprop-1-enyl)cyclopropane-1-carboxylate.

Also known as: (2-methyl-4-oxo-3-prop-2-enylcyclopent-2-en-1-yl) 2,2-dimethyl-3-(2-methylprop-1-enyl)cyclopropane-1-carboxylate, Allethrins, D-trans Allethrin, d-cis,trans-Allethrin.

IUPAC name
(2-methyl-4-oxo-3-prop-2-enylcyclopent-2-en-1-yl) 2,2-dimethyl-3-(2-methylprop-1-enyl)cyclopropane-1-carboxylate
CAS number
584-79-2
Molecular formula
C19H26O3
Molecular weight
302.4 g/mol
SMILES
CC1=C(C(=O)CC1OC(=O)C2C(C2(C)C)C=C(C)C)CC=C
PubChem CID
11442

Risk for dogs

Low risk

Dogs are tolerant of allethrin at typical mosquito coil and vaporizer use concentrations; the main precaution is ensuring adequate room ventilation when using coil products overnight. Direct ingestion of a mosquito coil (a dog chewing on an unlit coil) may cause mild GI signs from the allethrin and inert ingredients (corn starch binder) but systemic pyrethroid toxicity is unlikely at the small amount in one coil.

Risk for cats

High risk

Allethrin is a type I pyrethroid — cats are sensitive with T-syndrome risk (tremors, ataxia, hypersalivation). Mosquito coils and plug-in vaporizer mats used indoors are a significant chronic low-level inhalation exposure route for indoor cats, particularly in regions where allethrin-based mosquito control products are primary household use items (Japan, Southeast Asia, South Asia, tropical regions globally). Cats may also groom pyrethroid residue deposited on their fur from smoke or aerosol products. Treatment: remove from exposure source, bathing if dermal/coat contamination, methocarbamol for tremors, supportive care. The long duration of coil use (4–8 hours overnight) creates prolonged exposure that may exceed shorter aerosol spray scenarios.

Regulatory consensus

3 regulatory and scientific bodies have classified Allethrin. The classifications differ — that's the data.

AgencyYearClassificationNotes
EPA CTX / EPA OPP—Suggestive Evidence of Carcinogenicity but Not Sufficient to Assess Human Carcinogenic Potential
EPA CTX / Genetox—Genotoxicity: negative (Ames: None, 0 positive / 2 negative reports)
EPA CTX / Genetox—Genotoxicity: negative (Ames: None, 0 positive / 2 negative reports)

Regulators apply different standards of evidence — animal-data weighting, exposure-pattern assumptions, epidemiological power thresholds — which is why two scientific bodies can review the same data and reach different conclusions. The disagreement is the data.

Where pets encounter allethrin

  • Industrial Facilities — Manufacturing plants, Chemical storage areas, Waste treatment sites
  • Occupational Environments — Factories, Warehouses, Transportation vehicles

Safer alternatives

Lower-risk approaches that achieve a similar outcome to Allethrin:

  • Physical/mechanical pest control (IPM)
    Trade-offs: More labor-intensive. May not be sufficient for severe infestations.
    Relative cost: 1.2-2×

Frequently asked questions

Is allethrin safe for pets?

Dogs are tolerant of allethrin at typical mosquito coil and vaporizer use concentrations; the main precaution is ensuring adequate room ventilation when using coil products overnight. Direct ingestion of a mosquito coil (a dog chewing on an unlit coil) may cause mild GI signs from the allethrin and inert ingredients (corn starch binder) but systemic pyrethroid toxicity is unlikely at the small amount in one coil.

What products contain allethrin?

Allethrin appears in: Manufacturing plants (Industrial facilities); Chemical storage areas (Industrial facilities); Factories (Occupational environments); Warehouses (Occupational environments).

Why do regulators disagree about allethrin?

Allethrin has been classified by 3 agencies including EPA CTX / EPA OPP, EPA CTX / Genetox, EPA CTX / Genetox, with differing conclusions. Regulators apply different standards of evidence (animal data weighting, exposure-pattern assumptions, epidemiological power thresholds), which is why two scientific bodies can review the same data and reach different conclusions. See the regulatory consensus table on this page for the full picture.

See Allethrin in the pets app

Look up products containing allethrin, compare to alternatives, and explore the full data record.

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Sources (3)
  1. US EPA Pyrethroid Reregistration Eligibility Decision — cypermethrin/deltamethrin/lambda-cyhalothrin/bifenthrin/cyfluthrin/fenvalerate/tau-fluvalinate/fenpropathrin; type I/II classification; aquatic toxicity; cat sensitivity; sodium channel mechanism; human paresthesia; buffer zones (2011) (2011) — regulatory
  2. ASPCA Animal Poison Control Center: Pyrethroid Toxicosis in Cats and Dogs — type I vs type II CS/T syndromes; extreme cat sensitivity (sodium channel/UGT deficiency); bathing decontamination; methocarbamol tremor control; cyproheptadine; lipid emulsion severe cases (2023) (2023) — veterinary
  3. WHO: Mosquito Coil Emissions and Health Implications — pyrethroid composition; inhalation exposure estimates; allethrin, transfluthrin, metofluthrin; ventilation recommendations; human health risk assessment; bystander exposure in endemic regions (2011) (2011) — regulatory

Reference data, not professional advice. Aggregates publicly available regulatory and scientific data; not a substitute for veterinary, medical, legal, or regulatory advice. Why we built ALETHEIA →