Levamisole
Also known as: Levasole, Tramisol, Amtech, Ascaridil, Decaris, Ergamisol, Immunol, Ketrax, Meglum, Prohibit, Solaskil, Vermisol, Vizole
* **Strict Dosing:** Give this medication exactly as prescribed by your veterinarian. Levamisole has a narrow margin of safety, meaning the difference between an effective dose and a toxic dose is small. * **Adverse Effects:** Watch your pet closely for signs of toxicity such as excessive drooling, shaking, panting, vomiting, diarrhea, or unusual behavior. Contact your veterinarian immediately if these occur. * **Administration:** Do not give on an empty stomach or immediately after your pet drinks water if using orally for certain conditions (follow specific vet instructions). * **Food Animals:** Levamisole is not FDA-approved for use in dairy animals of breeding age. Adhere strictly to slaughter withdrawal times (e.g., 48 hours for cattle, 72 hours for sheep/swine). * **Retreatment:** Animals in heavily parasitized environments may need retreatment 2-4 weeks after the initial dose.
Dosage must be set by your veterinarian for your specific pet. Never give human medication or another pet’s prescription without veterinary guidance.
Veterinary professional? See the full dosing-by-species reference on VetSheet →
What it is used for
- For removal of mature and immature Dictyocaulus vivapurus
- For treatment of susceptible nematodes
- For removal of mature and immature Dictyocaulus vivapurus
- For treatment of susceptible nematodes
- For the treatment of lungworms
- For Aelurostrongylus abstrusus (lungworms)
- For Capillaria aerophilia (lungworms)
- For the treatment of lungworms
- For Capillaria aerophilia (lungworms)
- For treatment of Ollulanus tricuspis
- As a microfilaricide
- For adjunctive therapy of feline plasma-cell gingivitis/pharyngitis (immune-stimulant)
- For removal of mature and immature Dictyocaulus vivapurus
- For treatment of susceptible nematodes
- As an immunostimulant
- As adjunctive therapy for EPM
- For intestinal nematodes
- For gavage in Australian Parakeets (or desert species that refuse to drink water)
- For parenteral use
- For immunostimulation
- As a parenteral immunostimulant
- As a nebulized immunostimulant
- For Capillaria infections
- Poultry nematodes
- For Libyastrongylus douglassi in Ratites
- For removal of mature and immature Metastrongylus
- For nematodes in Rabbits
- For recurrent cutaneous infections (immune stimulant)
- As an immune stimulant
- For adjunctive therapy in dogs with chronic pyoderma
- For adjunctive therapy in dogs with chronic pyoderma
- As an alternative treatment for SLE
- As a microfilaricide
- For treatment of Angiostrongylus vasorum
- For Crenosoma vulpis (lungworms)
- For Capillaria (lungworms)
- For Filaroides osleri (lungworms)
- For Filaroides osleri (lungworms)
- For Capillaria aerophilia (lungworms)
- As an anthelmintic (Nematodes, Acanthocephalans, or Pentastomes)
How it is given
Possible side effects
- Cattle: Muzzle foaming, hypersalivation, excitement, trembling, lip-licking, head shaking, injection site swelling
- Sheep/Goats: Transient excitability, depression, hyperesthesia, salivation, stinging upon SC injection
- Swine: Salivation, muzzle foaming, coughing/vomiting (especially if infected with lungworms)
- Dogs: GI disturbances (vomiting, diarrhea), neurotoxicity (panting, shaking, agitation), immune-mediated anemia, agranulocytosis, dyspnea, pulmonary edema, immune-mediated skin eruptions (erythema multiforme, toxic epidermal necrolysis), lethargy
- Cats: Hypersalivation, excitement, mydriasis, vomiting
Cautions & contraindications
- Lactating dairy animals (not approved)
- Severely debilitated animals
- Patients with significant renal or hepatic impairment
- Cats with FIV or FIP (and likely ineffective in FeLV)
- Use as a dirofilarial adulticide
- Intravenous (IV) administration (never recommended)
- Intramuscular (IM) administration in birds (avoid if possible)
- > **Narrow Margin of Safety:** Levamisole has a narrow therapeutic index, especially in small animals and birds. Accurate dosing is critical. * **Stress:** Use cautiously or delay use in cattle that are stressed due to vaccination, dehorning, or castration. * **Pregnancy:** FDA Category C / Papich Class C. Has been implicated in causing abortion in goats. Use only if potential benefits outweigh risks. * **Nursing:** Excreted in cows' milk; use with caution in nursing dams.
Drug interactions
- Aspirin: Levamisole may increase salicylate levels
- Chloramphenicol: Fatalities have been reported after concomitant administration; avoid using these agents together
- Cholinesterase-inhibiting drugs (e.g., organophosphates, neostigmine): Could theoretically enhance the toxic effects of levamisole; use together with caution
- Nicotine-like compounds (e.g., pyrantel, morantel, diethylcarbamazine): Could theoretically enhance the toxic effects of levamisole; use together with caution
- Warfarin: Increased risk for bleeding
Frequently asked questions
What is Levamisole used for in pets?
• Strict Dosing: Give this medication exactly as prescribed by your veterinarian. Levamisole has a narrow margin of safety, meaning the difference between an effective dose and a toxic dose is small. • Adverse Effects: Watch your pet closely for signs of toxicity such as excessive drooling, shaking, panting, vomiting, diarrhea, or unusual behavior. Contact your veterinarian immediately if these occur. • Administration: Do not give on an empty stomach or immediately after your pet drinks water if using orally for certain conditions (follow specific vet instructions). • Food Animals: Levamisole is not FDA-approved for use in dairy animals of breeding age. Adhere strictly to slaughter withdrawal times (e.g., 48 hours for cattle, 72 hours for sheep/swine). • Retreatment: Animals in heavily parasitized environments may need retreatment 2-4 weeks after the initial dose.
Is Levamisole safe for my pet?
Dosage must be set by your veterinarian for your specific pet. Never give human medication or another pet’s prescription without veterinary guidance.
This article is for general education and is not a substitute for professional veterinary advice. If your pet is unwell, please consult a veterinarian.
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