Pet Safety / Compounds / Alpha-cypermethrin

Is Alpha-cypermethrin safe for dogs and cats?

Low risk for pets

Dogs metabolize alpha-cypermethrin efficiently via esterases; at label use concentrations for livestock ectoparasite control, dogs are not expected to be significantly harmed; direct accidental high-dose ingestion warrants supportive care.

What is alpha-cypermethrin?

The IUPAC name is trans-[(S)-cyano-(3-phenoxyphenyl)methyl] (1R,3R)-3-(2,2-dichloroethenyl)-2,2-dimethylcyclopropane-1-carboxylate.

Also known as: trans-[(S)-cyano-(3-phenoxyphenyl)methyl] (1R,3R)-3-(2,2-dichloroethenyl)-2,2-dimethylcyclopropane-1-carboxylate, Aeralfam, Alfoxylate, Ultimate.

IUPAC name
trans-[(S)-cyano-(3-phenoxyphenyl)methyl] (1R,3R)-3-(2,2-dichloroethenyl)-2,2-dimethylcyclopropane-1-carboxylate
CAS number
67375-30-8
Molecular formula
C22H19Cl2NO3
Molecular weight
416.3 g/mol
SMILES
CC1(C(C1C(=O)OC(C#N)C2=CC(=CC=C2)OC3=CC=CC=C3)C=C(Cl)Cl)C
PubChem CID
93357

Risk for dogs

Low risk

Dogs metabolize alpha-cypermethrin efficiently via esterases; at label use concentrations for livestock ectoparasite control, dogs are not expected to be significantly harmed; direct accidental high-dose ingestion warrants supportive care.

Risk for cats

Extreme risk

Alpha-cypermethrin is the active isomer pair of racemic cypermethrin — purified to the high-potency (1R,alpha-S) and (1S,alpha-R) enantiomers; feline toxicity is identical in mechanism and severity to cypermethrin but requires lower mass exposure due to higher per-molecule insecticidal activity. The feline safety concern is amplified because alpha-cypermethrin products used in public health malaria control (IRS) can be misused in household settings. Emergency treatment same as cypermethrin: bathing, methocarbamol, cyproheptadine.

Regulatory consensus

1 regulatory bodyhas classified Alpha-cypermethrin.

AgencyYearClassificationNotes
WHO—Class IItoxicity classification

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 alpha-cypermethrin

  • 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 Alpha-cypermethrin:

  • 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 alpha-cypermethrin safe for pets?

Dogs metabolize alpha-cypermethrin efficiently via esterases; at label use concentrations for livestock ectoparasite control, dogs are not expected to be significantly harmed; direct accidental high-dose ingestion warrants supportive care.

What products contain alpha-cypermethrin?

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

See Alpha-cypermethrin in the pets app

Look up products containing alpha-cypermethrin, compare to alternatives, and explore the full data record.

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Sources (2)
  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

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 →