What is the function of ivermectin injection?

October 9, 2025 •

3 min read

First developed in the 1970s, ivermectin became a cornerstone of parasite control in veterinary medicine. In this guide, we explore what is the function of ivermectin injection and its critical role in treating a variety of internal and external parasitic infestations in animals.

Quick Summary

Ivermectin injection is a potent broad-spectrum antiparasitic medication, primarily used in veterinary medicine, that paralyzes and kills internal and external parasites in livestock and pets.

Key Points

Broad-Spectrum Parasiticide: The primary function of ivermectin injection is to treat and control a wide range of internal and external parasites in animals.
Mechanism of Action: It works by binding to glutamate-gated chloride channels in invertebrate nerves and muscles, causing paralysis and death of the parasite.
Veterinary Application: The injectable form is used in livestock (cattle, swine) for gastrointestinal and lungworms, as well as external parasites like mites and lice.
Human vs. Animal Formulations: Ivermectin injections are strictly for animal use; human versions are typically oral or topical and dosed differently. Veterinary formulas can be toxic to humans.
Animal Safety: While generally safe, certain dog breeds with the MDR1 gene mutation can have severe reactions, and proper dosage from a veterinarian is critical.
Diverse Parasite Control: It effectively manages parasitic infections such as roundworms, lungworms, mange mites, and heartworm prevention in various species.

What is Ivermectin and How Does It Work?

Ivermectin is a macrocyclic lactone derived from Streptomyces avermitilis, used as an antiparasitic agent. It selectively targets the nervous system of invertebrates. The injectable form is popular in veterinary medicine for its broad effectiveness and ease of use.

The drug functions by activating glutamate-gated chloride ion channels in the nerve and muscle cells of many invertebrate parasites. This action increases chloride ion flow into cells, causing hyperpolarization. The resulting disruption of nerve impulses leads to parasite paralysis and death. Mammals are generally safe because they lack these specific channels in their central nervous system and ivermectin doesn't easily cross the blood-brain barrier at therapeutic doses.

The Function of Ivermectin Injection in Veterinary Practice

Ivermectin injection's main function is the control and treatment of various internal and external parasites in animals like cattle, swine, and pets.

Internal Parasites

Gastrointestinal Roundworms: Treats adult and larval forms of intestinal worms.
Lungworms: Used in animals like cattle and swine for respiratory health.
Threadworms: Effective against threadworms, particularly in sows to protect piglets.

External Parasites

Mange Mites: Highly effective against mites causing skin irritation.
Lice: Controls sucking lice in cattle and swine.
Cattle Grubs: Treats parasitic stages; timing is key to avoid issues.

Use in Companion Animals

Under veterinary guidance, ivermectin is used off-label in dogs and cats for:

Heartworm Prevention: Monthly administration.
Mites: Treatment of various mite infestations.
Internal Worms: Control of certain intestinal parasites.

Comparison of Ivermectin Injection Applications


Feature	Ivermectin Injection (Veterinary)	Ivermectin (Human)
Administration	Primarily subcutaneous injection.	Oral tablets or topical creams/lotions.
Primary Use	Broad-spectrum control of internal and external parasites in livestock (cattle, swine) and pets.	Treatment of specific parasitic infections like onchocerciasis (river blindness), strongyloidiasis, scabies, and lice.
Target Parasites	Gastrointestinal roundworms, lungworms, mange mites, and lice in animals.	Nematode and arthropod parasites in humans, but formulations differ.
Human Safety	Veterinary formulations are not for human use and can be toxic or lethal due to high concentration.	FDA-approved oral and topical formulations are dosed and formulated specifically for human safety.

Risks and Precautions

Ivermectin injections require careful use. Veterinary formulations are highly concentrated and dangerous for human use.

Certain dog breeds with the MDR1 gene mutation (e.g., collies, Australian shepherds) are sensitive to ivermectin and may experience neurological side effects at higher doses. Always follow veterinary instructions.

Overdose in humans can cause severe side effects, including neurological problems, nausea, coma, and death. The FDA advises against using ivermectin for unapproved uses, like treating COVID-19, due to potential dangers.

Conclusion

The main function of ivermectin injection is to effectively treat and control internal and external parasites in animals. Its specific action on invertebrate chloride channels has significantly advanced veterinary parasite management in livestock and pets. It's crucial to remember that the injectable form is strictly for veterinary use and requires species-specific dosing for safety. Human use involves different oral or topical formulations for specific infections, and veterinary products are toxic as a substitute. Safe and effective use depends on guidance from a qualified veterinarian or healthcare provider.

For additional information on the safety and administration of veterinary products, consulting resources like the FDA's Center for Veterinary Medicine is recommended.

Frequently Asked Questions

Ivermectin injection in livestock, such as cattle and swine, is used to treat internal parasites like gastrointestinal roundworms and lungworms, as well as external parasites like mange mites and sucking lice.

Ivermectin injections should only be administered to pets under the direct supervision and prescription of a veterinarian. They may be used off-label for conditions like heartworm prevention or certain mite infections in specific dosages.

Veterinary ivermectin injections are formulated and concentrated for animal use and can be highly toxic and dangerous if used by humans. In addition to dose size, different inactive ingredients are used.

Ivermectin binds to and opens glutamate-gated chloride channels on the nerve and muscle cells of parasites. This allows chloride ions to flood the cells, causing hyperpolarization and leading to paralysis and death.

Yes, some herding breeds like collies, Australian shepherds, and their crosses with the MDR1 gene mutation can be particularly sensitive to ivermectin at higher doses. A veterinarian can determine safe usage and testing may be an option.

While ivermectin was investigated for potential antiviral properties, major health organizations, including the FDA, have advised that it is not approved or recommended for the prevention or treatment of COVID-19.

No, ivermectin does not affect mammals in the same way because they lack the specific glutamate-gated chloride channels that the drug targets in invertebrates. The drug also does not readily cross the blood-brain barrier in mammals.