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Rodenticides

Rodenticides compared

Rodenticides fall into two groups: anticoagulants, which stop blood clotting, and non-anticoagulants such as bromethalin, cholecalciferol and zinc phosphide, which work in different ways.[1]

The short answer

  • Stores may sell homeowners only ready-to-use bait stations holding block or paste bait. Second-generation anticoagulants such as brodifacoum are kept to professional and farm products. EPA's restrictions page lists bromethalin, chlorophacinone and diphacinone in the consumer stations now registered; its safe-use page also allows cholecalciferol, warfarin and zinc phosphide.[2][5][3]
  • Anticoagulant poisoning is treated with vitamin K1. Bromethalin, cholecalciferol and zinc phosphide are not anticoagulants, so that antidote doesn't apply: the bromethalin and cholecalciferol labels give doctors and vets other treatments, and bromethalin has no specific antidote.[4][2][8][9][18]
  • Pets are most often poisoned by eating the bait itself; dogs account for most pet deaths. Dead rodents can also carry enough poison to harm a pet.[3]
  • Snap traps placed along walls and rodent runways are an effective alternative around homes and avoid poisoning risks; set them inside boxes where pets or children could reach them.[3]
  • Limits on anticoagulants have pushed more use toward bromethalin and cholecalciferol. Bromethalin cases in pets have risen, and both poisons now turn up in wildlife.[13][19][14][20]

The main types

  • First-generation (multiple-feeding) anticoagulants: warfarin, chlorophacinone and diphacinone. Rodents usually need to feed over several days.[1]
  • Second-generation (single-dose) anticoagulants: brodifacoum, bromadiolone and difethialone. More toxic, stored in the liver, and one feeding can be lethal; restricted to professionals since 2011.[1][3]
  • Bromethalin: stops nerve cells in the brain from producing energy, causing swelling and paralysis; a single-dose rodenticide.[1]
  • Cholecalciferol (vitamin D3): raises blood calcium to toxic levels; rodents must eat several doses. It is not an anticoagulant, and the treatment notes on its label deal with the high calcium: calcitonin for people; fluids, furosemide, corticosteroids and phosphate binders for pets.[1][2][9]
  • Zinc phosphide: turns into toxic phosphine gas in the stomach and kills within several hours of a lethal dose.[1][3]
  • Sources disagree on how bromethalin is eaten. NPIC calls it a single-dose rodenticide, while UC IPM says bromethalin and cholecalciferol baits are made to work as chronic poisons that rats feed on one or more times over one to several days.[1][3]
  • Difenacoum is a fourth second-generation anticoagulant registered in the United States, alongside brodifacoum, bromadiolone and difethialone.[2][6]
  • Strychnine is also registered but can be used only below ground, and products with more than 0.5% strychnine are sold only to certified applicators.[1][6]

How fast each one works

Anticoagulants are slow on purpose. EPA says deaths typically come four days to two weeks after rodents start feeding on the bait. Because the body has a stored supply of clotting factors that has to run out first, signs in a poisoned animal may not show for up to five days.[2][1]

Second-generation anticoagulants kill over a similar stretch of time, so a rat keeps eating after it has taken a lethal dose. Its carcass can end up holding several times the lethal amount, which is what makes these baits dangerous to predators and scavengers.[2][6][1]

Zinc phosphide is the fast one: death within several hours of a lethal dose. Rats are wary of it, so it often needs pre-baiting with untreated bait first, which is one reason it's seldom used on rats and is typically unavailable to homeowners.[3]

Signs of poisoning and what vets do

Anticoagulants: bleeding anywhere in the body, often not visible. Poisoned animals may have trouble breathing, weakness and lethargy; less common signs include bleeding gums, bruising, black tarry stools, vomiting and coughing. Children usually eat small amounts and may never show signs. Some baits contain blue or green dye that helps show whether a child or pet has handled or eaten them.[1]

For pets that ate anticoagulant bait, the label tells vets to give vitamin K1 and, if needed, to recheck clotting times every 3 days until they return to normal, for up to 30 days. Severe cases may need blood transfusions.[4]

Bromethalin: tremors, seizures, loss of control of the hind legs, vomiting and coma. Signs can start 8 to 12 hours or several days after a lethal dose. A veterinary review puts toxic doses as low as 0.3 mg/kg in cats and 2.5 mg/kg in dogs, says there is no specific antidote, and relies on early vomiting and repeated activated charcoal.[1][18]

The outlook for dogs depends on the dose. In 192 dogs seen after eating bromethalin bait, only 25 developed signs and 187 survived to go home; most had eaten far less than a dose expected to cause signs, but the five dogs that arrived with severe nerve signs were euthanized. The review above calls the prognosis guarded to poor once a dog or cat has true toxicosis.[12][18]

Cats appear to be more vulnerable. In California lab cases from 2010 to 2023, suspected bromethalin cases in dogs and cats rose 2.8-fold from the first seven years to the second, cats were more likely to have the poison confirmed, and brain lesions matching bromethalin were found at autopsy in 24 of 25 cats but only 2 of 8 dogs.[13]

Cholecalciferol: vomiting, diarrhea, loss of appetite and depression within 12 to 36 hours, then heavy thirst and urination; the kidneys may fail within one or two days. Signs can last for weeks because the body stores it, and survivors may have lasting kidney and muscle damage. One case report describes long-term treatment in a dog whose vitamin D levels stayed high after the acute phase.[1][19]

Zinc phosphide: vomiting within an hour, though signs may be delayed 4 hours or, in some cases, more than 18 hours. The vomit may smell like garlic. Of 362 dogs reported to an animal poison control center after eating zinc phosphide, more than half showed no signs, and 98.3% of those with known outcomes survived.[1][17]

If a pet eats any bait, call a veterinarian at once and have the EPA registration number from the label ready, since the active ingredient decides the treatment. For a person, call Poison Control at 1-800-222-1222, or 911 if the person is unconscious, having trouble breathing or having convulsions. The bait station guide covers the first steps in more detail.[4][8][9][7][1]

Secondary poisoning: risk to pets and wildlife that eat poisoned rodents

NPIC's ratings for mammals such as dogs and cats: high risk for chlorophacinone, diphacinone, bromadiolone, difethialone and brodifacoum; low risk for warfarin and zinc phosphide; low risk based on limited evidence for bromethalin and cholecalciferol.[1]

For birds such as hawks and owls: high risk for difethialone and brodifacoum; moderate for diphacinone and bromadiolone; low for warfarin, chlorophacinone and zinc phosphide.[1]

Lower secondary risk does not mean safe: any of these can poison a pet that eats the bait directly, and newer evidence suggests secondary exposure to bromethalin can occur.[3]

Single-dose anticoagulants carry more risk to predators because residues can stay in liver tissue for many weeks, so a predator that eats many poisoned rodents can build up a toxic dose over time. Even the multiple-dose anticoagulants can poison animals that eat poisoned rodents.[1]

Zinc phosphide breaks down quickly. It poses a secondary risk only when a rodent is just dying or very recently dead with intact bait still in its stomach.[1]

Field studies show how far the anticoagulants spread. Of 133 bald and golden eagles tested in the U.S., 82% carried anticoagulant residues and brodifacoum was found in 81%; anticoagulant poisoning killed 12 of the 303 eagles examined. Among 44 hawks and owls at a Massachusetts wildlife clinic in 2021 and 2022, 95.5% carried anticoagulants.[15][16]

Newer work has found bromethalin moving up the food chain, which NPIC's 'low risk' rating predates. The Massachusetts study found bromethalin's more toxic breakdown product in 29.5% of the hawks and owls. In California, bromethalin exposure was confirmed in 131 of 537 wild mammal carcasses tested from 2017 to 2024, and 33 of those animals, mostly raccoons, gray foxes and striped skunks, met the criteria for bromethalin poisoning.[16][14][1]

Restrictions do show up in wildlife. In barred owls from northwestern California forests, predicted anticoagulant exposure in young owls fell from about 50% in 2019 to about 20% in 2024 as state limits tightened, while cholecalciferol detections rose, which the authors read as possible product substitution.[20]

Federal rules

EPA's 2008 risk mitigation decision set the current consumer rules: packages of one pound or less, no second-generation anticoagulants in products for homeowners, and tamper- and weather-resistant stations for outdoor above-ground use where children, pets and wildlife may be present. UC IPM notes the changes took effect in mid-2011.[6][3]

Consumer stations are labeled either for indoor use only or for indoor use and outdoor use within 50 feet of buildings, depending on whether the station passed tests against tampering by young children and dogs and against weather. Read the label for where you plan to put it.[2]

Professional and farm baits may not be sold in drug, grocery, hardware or club stores. Second-generation products come in containers of at least 16 pounds (professional) or 8 pounds (agricultural); first-generation, bromethalin, cholecalciferol and zinc phosphide products come in at least 4 pounds.[2]

In November 2022 EPA proposed further changes for 11 rodenticides: making all second-generation anticoagulants, strychnine and zinc phosphide restricted-use (certified applicators only); making first-generation, bromethalin and cholecalciferol products over one pound restricted-use; banning refillable consumer stations and consumer zinc phosphide products; and requiring users to search for and dispose of dead rodents. EPA's review page still lists these as proposals, with an interim decision as the next step.[6]

Reducing the risk

  • Keep all rodenticides, in use or in storage, out of reach of children and pets. Flavored baits attract dogs, which may dig them up.[1]
  • Choose a bait station rated for your situation; some resist only children, others resist children, pets and weather.[1]
  • Search for, collect and dispose of dead rodents with gloves, and keep trash lids secured.[1]
  • Tamper-resistant stations are required outdoors above ground and wherever children, pets or other animals could reach the bait.[4]

State rules can be stricter

California currently prohibits most uses of first- and second-generation anticoagulant rodenticides; old products should go to a household hazardous waste facility.[3]

California's law has two steps. Since January 1, 2021, AB 1788 has barred use of brodifacoum, bromadiolone, difenacoum and difethialone, including residential and home uses, with exemptions for uses such as farms, water-supply facilities and vector control. Since January 1, 2025, AB 2552 has extended the ban to most uses of chlorophacinone and warfarin.[10][11]

Common questions

Which rat poison is safest around dogs?
None is safe if a dog eats the bait; most pet deaths involve dogs eating bait directly. Anticoagulant poisoning can be treated with vitamin K1 if caught early. Traps and tamper-resistant stations reduce the risk.[3][4]
Why can't I buy brodifacoum?
EPA restricted second-generation anticoagulants to agricultural and professional users in 2011 because of risks to children, pets and wildlife.[3][2]
Is there an antidote for bromethalin?
No. Its label says it is not an anticoagulant and directs doctors and vets to limit absorption and treat brain swelling; a veterinary review confirms there is no specific antidote. Get a pet that ate bromethalin bait to a vet quickly, since early decontamination is the main treatment.[8][18]
Which rat poison is most dangerous to owls and hawks?
Brodifacoum and difethialone rate high risk for birds that eat poisoned rodents, and brodifacoum was found in 81% of eagles tested in a U.S. study. NPIC rates bromethalin low risk on limited evidence, but its more toxic breakdown product has since been found in hawks and owls.[1][15][16]

Sources

  1. National Pesticide Information Center, “Rodenticides Topic Fact Sheet.” npic.orst.edu/factsheets/rodenticides.html (accessed 2026-11-10)
  2. U.S. Environmental Protection Agency, “Restrictions on Rodenticide Products.” www.epa.gov/rodenticides/restrictions-rodenticide-products (accessed 2026-11-10)
  3. University of California Statewide IPM Program, “Pest Notes: Rats, Publication 74106 (revised June 2024).” ipm.ucanr.edu/legacy_assets/PDF/PESTNOTES/pnrats.pdf (accessed 2026-11-10)
  4. U.S. EPA Pesticide Product Label System, “Brodifacoum rodenticide pellets label, EPA Reg. No. 61282-109 (EPA-stamped, Oct. 15, 2026).” www3.epa.gov/pesticides/chem_search/ppls/061282-00109-20261015.pdf (accessed 2026-11-10)
  5. U.S. Environmental Protection Agency, “Safely Use Rodent Bait Products.” www.epa.gov/rodenticides/safely-use-rodent-bait-products (accessed 2026-11-10)
  6. U.S. Environmental Protection Agency, “Rodent Control Pesticide Safety Review.” www.epa.gov/rodenticides/rodent-control-pesticide-safety-review (accessed 2026-11-10)
  7. U.S. Environmental Protection Agency, “In Case of Pesticide Emergency.” www.epa.gov/rodenticides/case-pesticide-emergency (accessed 2026-11-10)
  8. U.S. EPA Pesticide Product Label System, “Bromethalin rodenticide bait label, EPA Reg. No. 12455-140 (EPA-stamped, Sept. 8, 2020).” www3.epa.gov/pesticides/chem_search/ppls/012455-00140-20200908.pdf (accessed 2026-11-10)
  9. U.S. EPA Pesticide Product Label System, “Cholecalciferol rodenticide bait label, EPA Reg. No. 12455-106 (EPA-stamped, Apr. 30, 2021).” www3.epa.gov/pesticides/chem_search/ppls/012455-00106-20210430.pdf (accessed 2026-11-10)
  10. California Department of Pesticide Regulation, “New Second Generation Anticoagulant Rodenticide Prohibitions and Allowed Uses: Questions and Answers (ENF 20-20).” www.cdpr.ca.gov/cac-letter/new-second-generation-anticoagulant-rodenticide-prohibitions-and-allowed-uses-questions-and-answers/ (accessed 2026-11-10)
  11. California Department of Pesticide Regulation, “Chlorophacinone and Warfarin: Restricted Material Status, Prohibitions, Allowed Uses, and Questions and Answers (ENF 24-20).” www.cdpr.ca.gov/cac-letter/chlorophacinone-and-warfarin-restricted-material-status-prohibitions-allowed-uses-and-questions-and-answers/ (accessed 2026-11-10)
  12. Journal of Veterinary Emergency and Critical Care, abstract via PubMed, “Scotti KM et al. 2021. Retrospective evaluation of the effects and outcome of bromethalin ingestion: 192 dogs (2010-2016). J Vet Emerg Crit Care 31(1):94-98.” pubmed.ncbi.nlm.nih.gov/33142049/ (accessed 2026-11-10)
  13. Journal of Veterinary Internal Medicine, abstract via PubMed, “Klainbart S et al. 2025. Bromethalin exposure in dogs and cats: a 14-year retrospective study (2010-2023) from the California Animal Health and Food Safety Laboratory System. J Vet Intern Med 39(3):e70057.” pubmed.ncbi.nlm.nih.gov/40135768/ (accessed 2026-11-10)
  14. Environmental Pollution, abstract via PubMed, “Bourbour RP et al. 2026. Patterns of bromethalin exposure and toxicosis in California mammals across a shifting rodenticide use landscape. Environ Pollut 411:129245.” pubmed.ncbi.nlm.nih.gov/42790577/ (accessed 2026-11-10)
  15. PLoS One, abstract via PubMed, “Niedringhaus KD et al. 2021. Anticoagulant rodenticide exposure and toxicosis in bald eagles and golden eagles in the United States. PLoS One 16(4):e0246134.” pubmed.ncbi.nlm.nih.gov/33826627/ (accessed 2026-11-10)
  16. Environmental Pollution, abstract via PubMed, “Murray M, Cox EC. 2023. Active metabolite of the neurotoxic rodenticide bromethalin along with anticoagulant rodenticides detected in birds of prey in the northeastern United States. Environ Pollut.” pubmed.ncbi.nlm.nih.gov/37336352/ (accessed 2026-11-10)
  17. Journal of the American Veterinary Medical Association, abstract via PubMed, “Gray SL et al. 2011. Potential zinc phosphide rodenticide toxicosis in dogs: 362 cases (2004-2009). J Am Vet Med Assoc.” pubmed.ncbi.nlm.nih.gov/21879965/ (accessed 2026-11-10)
  18. Topics in Companion Animal Medicine, abstract via PubMed, “Peterson ME. 2013. Bromethalin. Top Companion Anim Med.” pubmed.ncbi.nlm.nih.gov/23796484/ (accessed 2026-11-10)
  19. Frontiers in Veterinary Science, abstract via PubMed, “Gerhard C, Jaffey JA. 2019. Persistent increase in serum 25-hydroxyvitamin D concentration in a dog following cholecalciferol intoxication. Front Vet Sci.” pubmed.ncbi.nlm.nih.gov/31998760/ (accessed 2026-11-10)
  20. Environmental Pollution, abstract via PubMed, “Jirinec V et al. 2026. Forest food web contamination by rodenticides is pervasive but responsive to regulation: insights from Barred Owl biomonitoring. Environ Pollut.” pubmed.ncbi.nlm.nih.gov/42772436/ (accessed 2026-11-10)

Updated 2026-11-10. Built from sourced records. Spot an error? Tell us.