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Drugs Used to Treat Common Gastrointestinal Parasites in Backyard Poultry

Active Ingredient / ProductCategoryDrug / Chemical ClassPrimary Parasite TargetsRoute(s) of AdministrationEgg Withdrawal Risk (qual.)Meat Withdrawal Risk (qual.)Use in Layers?U.S. Regulatory Status (summary)Dosage Recommendations Cited in Peer Reviewed Literature or Product LabelsCompliance notes
Fenbendazole (SAFE-GUARD® AquaSol®)AnthelminticBenzimidazoleRoundworms (Ascaridia), cecal worms (Heterakis) (label-dependent); some other nematodesOral (drinking water)0-day egg withdrawal when used according to the label0-day meat withdrawal when used according to the labelYes (per label when used as directed)FDA-approved for chickens (label-specific indications); follow labelDose: 1 mg/kg body weight (0.454 mg/lb) daily - 0.0023 ml/lb. Schedule: Administered via drinking water for 5 consecutive days.Extra-label dosing: Capillaria worms - 2X dose; tapeworms - 20 mg/kg for 3 consecutive days. 14-day withdrawal. Flocks under 22 lbs - create a 1:10 dilution (1 part AquaSol, 9 parts water) dose at 0.023 ml/lb. Toxic in pigeons.
Albendazole (Valbazen®; other)AnthelminticBenzimidazoleNematodes; some cestodes (tapeworms) (variable efficacy)Oral14-day withdrawal for eggs14-day withdrawal for meatNo / Extra-labelNot labeled for U.S. poultry; extra-label use in food birds creates residue risk10 mg/kg of body weight administered as a single oral dose.Administration during molt or in young birds causes feather deformities and toxicity, particularly in pigeons, which are highly sensitive to benzimidazoles. Toxic in pigeons.
Flubendazole (EU/UK poultry dewormer; jurisdiction dependent)AnthelminticBenzimidazoleNematodes (Ascaridia; Capillaria spp. depending on label)Oral (feed/water depending on product)0-day egg withdrawal when used according to the EU label7-day meat withdrawal when used according to the EU labelYes where labeled (follow withdrawal)Not a standard U.S. labeled poultry product; common in EU/UKDose in Feed: 30 ppm (30 mg active ingredient per kg of feed) for chickens and geese. 7 Consecutive Days.Flubendazole is almost exclusively administered via feed (medicated feed) for 7 consecutive days. The European Union (EU) Maximum Residue Limit (MRL) for flubendazole in eggs is 400 µg/kg. All info related to EU label
Levamisole (Levamed®, Prohibit®)AnthelminticImidazothiazoleNematodes (roundworms; variable across species)Oral21 days18 days for meat.No / Extra-labelNot approved for poultry use in the U.S.; residue limits/egg tolerances not establishedChickens: 18–36 mg/kg PO, administered as a single dose in drinking water.Because Levamisole is not FDA-approved for use in poultry in the United States, there is no official label withdrawal period. Its use is considered "extra-label" (ELDU), and withdrawal times are based on pharmacokinetic studies and expert recommendations rather than regulatory approval.
Ivermectin (Ivomec® Pour-On, Noromectin® Pour-On)Endectocide (worms + mites) (off-label in poultry)Macrocyclic lactoneSome nematodes; some external parasites (mites/lice) (variable)Oral / topical / injectable (species products; poultry use off-label)12-week egg withdrawal (no U.S. poultry tolerance; residues a major concern)12-week meat withdrawalNo (U.S. food birds)Not approved for any poultry species in the U.S.; no tolerance for egg/meat residues0.2 mg/kg - 0.4 mg/kg (0.02 ml/lb - 0.04 ml/lb) Topical formulation, two doses 10-14 days apart applied to the skin at the base of the neck. One drop equals approximately 0.05 mlHighly liphylic (concentrates in fat tissue/egg yolk). Seek alternatives if possible.
Moxidectin (Cydectin® Pour-On 0.5% [5 mg/ml])Endectocide (off-label in poultry)Macrocyclic lactoneNematodes; some ectoparasites (variable)Oral / topical (product dependent)12-week egg withdrawal (no U.S. poultry tolerance; residues a major concern)12-week meat withdrawal (no U.S. poultry tolerance; residues a major concern)No (food birds) / uncertainNot a standard labeled poultry product in the U.S.; treat as high residue risk0.2 mg/kg to 0.5 mg/kg of body weight.Highly liphylic (concentrates in fat tissue/egg yolk). Seek alternatives if possible.
Praziquantel (Droncet®, Drontal®)AnthelminticIsoquinoline-pyrazineTapeworms (cestodes); some flukes (trematodes) (species-dependent)Oral21-day withdrawal for eggs28-day withdrawal for meatNo (U.S. food birds)Not approved for U.S. poultry; considered experimental/off-label in food birdsPraziquantel: 10-20 mg/kg orally for tapeworms (off-label).If using a combination product (e.g., Equimax), you must calculate the dose based on the praziquantel component and ensure the ivermectin dose remains safe (avoiding overdose in sensitive waterfowl).
Piperazine (Wazine)AnthelminticPiperazine derivativeLarge roundworms (ascarids) primarilyOral (water/feed; product dependent)14-day withdrawal for eggs14-day withdrawal for meatYes where labeled (follow withdrawal)Regulatory status depends on specific product and bird class; verify label for egg birds1 oz (30 mL) per 1 gallon of water.Piperazine products labeled for poultry (like Wazine) were voluntarily withdrawn from the US market by manufacturers or are currently unavailable/discontinued for poultry use.
Pyrantel pamoate (Nemex-2 )AnthelminticTetrahydropyrimidineAscarids and some nematodes (varies)Oral8-week withdrawal for eggs28-day withdrawal for eggsNo (U.S. food birds)Not a labeled poultry product in U.S.; residue guidance limited4.5 mg/kg – 10 mg/kgPyrantel Pamoate is a common dewormer for dogs and cats that is occasionally used extra-label in poultry. It is considered safe but has a limited spectrum of activity in birds.

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Dr. Blayne Mozisek

CEO & Founder of Poultry Doc, Inc