Pet Safety / Compounds / Lambda-cyhalothrin

Is Lambda-cyhalothrin safe for dogs and cats?

Extreme risk for cats · Low risk for dogs

Not veterinary or professional safety advice, and not a substitute for a veterinarian — consult one about your animal. Full disclaimer →

Lambda-cyhalothrin is a potent type II alpha-cyano pyrethroid with extreme cat toxicity consistent with the pyrethroid class; accidental exposure via household aerosol sprays, foggers, or contact with recently treated surfaces causes rapid-onset tremors, hypersalivation, seizure, and respiratory distress in cats. The alpha-cyano group confers the most severe neurological signs (CS syndrome) in cats. Prompt decontamination (bathing) and emergency veterinary care are critical; prognosis is guarded with intensive care but good if treated before severe hyperthermia develops.

What is lambda-cyhalothrin?

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

Also known as: trans-[(R)-cyano-(3-phenoxyphenyl)methyl] (1S,3S)-3-[(Z)-2-chloro-3,3,3-trifluoroprop-1-enyl]-2,2-dimethylcyclopropane-1-carboxylate, Karate, Icon, Warrior.

IUPAC name
trans-[(R)-cyano-(3-phenoxyphenyl)methyl] (1S,3S)-3-[(Z)-2-chloro-3,3,3-trifluoroprop-1-enyl]-2,2-dimethylcyclopropane-1-carboxylate
CAS number
91465-08-6
Molecular formula
C23H19ClF3NO3
Molecular weight
449.8 g/mol
SMILES
CC1(C(C1C(=O)OC(C#N)C2=CC(=CC=C2)OC3=CC=CC=C3)C=C(C(F)(F)F)Cl)C
PubChem CID
6440557

Risk for dogs

Low risk

Lambda-cyhalothrin is used in livestock ectoparasiticide formulations and as a grain protectant; dogs are relatively tolerant at typical exposure concentrations. Accidental high-dose ingestion (e.g., licking treated surfaces) may cause mild GI signs and transient tremors; formulation solvents (petroleum distillates in some sprays) can contribute to toxicity via aspiration or GI irritation. No veterinary-approved lambda-cyhalothrin formulations for dogs/cats exist.

Risk for cats

Extreme risk

Lambda-cyhalothrin is a potent type II alpha-cyano pyrethroid with extreme cat toxicity consistent with the pyrethroid class; accidental exposure via household aerosol sprays, foggers, or contact with recently treated surfaces causes rapid-onset tremors, hypersalivation, seizure, and respiratory distress in cats. The alpha-cyano group confers the most severe neurological signs (CS syndrome) in cats. Prompt decontamination (bathing) and emergency veterinary care are critical; prognosis is guarded with intensive care but good if treated before severe hyperthermia develops.

Regulatory consensus

2 regulatory and scientific bodies have classified Lambda-cyhalothrin. The classifications differ — that's the data.

AgencyYearClassificationNotes
EPA CTX / EPA OPP—Group D Not Classifiable as to Human Carcinogenicity
US_EPA2024registered_restrictedEPA restricted-use pyrethroid.

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 lambda-cyhalothrin

  • 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 Lambda-cyhalothrin:

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

Frequently asked questions

Is lambda-cyhalothrin safe for pets?

Lambda-cyhalothrin is a potent type II alpha-cyano pyrethroid with extreme cat toxicity consistent with the pyrethroid class; accidental exposure via household aerosol sprays, foggers, or contact with recently treated surfaces causes rapid-onset tremors, hypersalivation, seizure, and respiratory distress in cats. The alpha-cyano group confers the most severe neurological signs (CS syndrome) in cats. Prompt decontamination (bathing) and emergency veterinary care are critical; prognosis is guarded with intensive care but good if treated before severe hyperthermia develops.

What products contain lambda-cyhalothrin?

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

Why do regulators disagree about lambda-cyhalothrin?

Lambda-cyhalothrin has been classified by 2 agencies including EPA CTX / EPA OPP, US_EPA, 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 Lambda-cyhalothrin in the pets app

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

Open in pets View raw API data

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 →