What Parasites Will Ivermectin Get Rid Of? A Comprehensive Guide

October 6, 2025 •

4 min read

Millions of people worldwide have benefited from ivermectin, a versatile pharmaceutical first introduced in the 1980s. This broad-spectrum antiparasitic has a profound impact on global public health and can treat a variety of parasitic diseases, but many wonder what parasites will ivermectin get rid of specifically.

Quick Summary

Ivermectin is an effective antiparasitic agent that eradicates a wide array of internal and external parasites, including nematodes (roundworms, threadworms) and ectoparasites like scabies mites and head lice. It works by paralyzing and killing parasites, and its targets include the causes of river blindness and lymphatic filariasis.

Key Points

Broad Spectrum Activity: Ivermectin is effective against a variety of internal and external parasites, including nematodes (worms) and ectoparasites (mites and lice).
Target Parasites: It is a core treatment for onchocerciasis (river blindness), lymphatic filariasis, strongyloidiasis, scabies, and lice infestations.
Invertebrate-Specific Mechanism: The drug works by binding to glutamate-gated chloride channels found in invertebrate parasites, paralyzing and killing them.
Human vs. Animal Formulations: Highly concentrated veterinary formulations are not safe for human use and can be toxic, emphasizing the need for a medical prescription and proper dosage.
Medical Supervision is Crucial: Use of ivermectin should only be under the guidance of a healthcare provider for FDA-approved indications due to potential side effects and risks associated with misuse.

Mechanism of Action

Ivermectin is derived from avermectin and works primarily by interfering with the nerve and muscle function of invertebrates. It binds selectively and with high affinity to glutamate-gated chloride ion channels found in the nerve and muscle cells of many parasites. This binding action increases the permeability of the parasite's cell membrane to chloride ions, causing hyperpolarization of the cell. The result is the paralysis and eventual death of the parasite.

Ivermectin is considered safe for humans and most mammals at therapeutic doses because the target glutamate-gated chloride channels are not found in the central nervous system of vertebrates. Additionally, a protective mechanism called the P-glycoprotein efflux pump further limits the drug's ability to cross the mammalian blood-brain barrier.

Parasites Eradicated by Ivermectin

Ivermectin's effectiveness spans a range of internal and external parasitic infections in both humans and animals. Its application is crucial in mass drug administration campaigns for diseases endemic to tropical regions.

Filarial Worms

Onchocerciasis (River Blindness): Caused by the worm Onchocerca volvulus and transmitted by blackflies, this disease leads to skin and eye damage from the migrating microfilariae. Ivermectin is highly effective against the microfilariae but does not kill the adult worms. Treatment is administered in single annual or semi-annual doses to control the microfilariae and prevent disease progression.
Lymphatic Filariasis (Elephantiasis): This disease is caused by filarial worms such as Wuchereria bancrofti and transmitted by mosquitoes. Ivermectin is an important component of mass drug administration programs, often in combination with other drugs, to clear circulating microfilariae.

Intestinal Worms (Nematodes)

Strongyloidiasis: Caused by the threadworm Strongyloides stercoralis, this infection is typically treated with a single dose of ivermectin, which is often more effective than other treatments like albendazole.
Ascariasis: Infections from the large roundworm Ascaris lumbricoides are responsive to ivermectin, which is sometimes used in combination therapy.
Trichuriasis: Caused by whipworms (Trichuris trichiura), this is another intestinal infection for which ivermectin is effective.
Cutaneous Larva Migrans: This skin condition caused by hookworm larvae is effectively treated with one to two doses of ivermectin.
Other Soil-Transmitted Helminths: Ivermectin has also demonstrated efficacy against other soil-transmitted helminths.

Ectoparasites

Scabies: Infestation with the mite Sarcoptes scabiei is treated with ivermectin, either orally or topically. For cases of crusted (Norwegian) scabies, oral ivermectin is particularly beneficial. While oral ivermectin may not be FDA-approved for scabies in the U.S., it is often used effectively off-label, especially in large outbreaks or when topical treatment is difficult.
Lice Infestations (Pediculosis): Ivermectin is effective against head lice (Pediculus humanus capitis), with both oral and topical formulations available.
Rosacea: Topical ivermectin cream is FDA-approved for treating the inflammatory lesions of rosacea, which can be linked to Demodex mites.
Myiasis: This is an infestation of fly larvae, and oral ivermectin has been used successfully in its treatment.

Comparison with Other Antiparasitic Drugs

When treating parasitic infections, medical professionals consider several factors, including the type of parasite, the patient's condition, and potential side effects. Here is a comparison of ivermectin with two other common antiparasitic agents, mebendazole and albendazole.


Feature	Ivermectin	Mebendazole	Albendazole
Mechanism of Action	Binds to glutamate-gated chloride channels in invertebrates, causing paralysis and death.	Inhibits microtubule formation and glucose uptake in worms, leading to energy depletion and death.	Inhibits tubulin polymerization and causes impaired glucose uptake in worms.
Primary Targets	Filarial worms, intestinal nematodes (Strongyloides), and ectoparasites (mites, lice).	Intestinal nematodes (pinworm, roundworm, whipworm).	Broad-spectrum, including intestinal nematodes and some cestode (tapeworm) infections.
Common Side Effects	Dizziness, nausea, itching, rash, abdominal pain.	Abdominal pain, nausea, vomiting, diarrhea.	Abdominal pain, nausea, headache, dizziness, increased liver enzymes.
Human Formulation	Oral tablets, topical cream, topical lotion.	Oral tablets.	Oral tablets, oral suspension.
FDA Approval	Approved for strongyloidiasis and onchocerciasis.	Approved for pinworm, whipworm, roundworm, and hookworm.	Approved for certain cestode and nematode infections.

Important Considerations for Safe Use

It is crucial to use ivermectin only as prescribed by a licensed healthcare provider. The drug is available in formulations specifically for humans and should not be confused with or substituted for veterinary-grade products. Animal formulations are often highly concentrated and can contain ingredients not safe for human consumption, leading to potential toxicity, seizures, or coma.

Additionally, high doses of ivermectin can cause side effects such as nausea, vomiting, dizziness, and nervous system problems. The American Medical Association and FDA strongly oppose the use of ivermectin for off-label purposes, such as treating or preventing COVID-19, due to a lack of evidence for efficacy and a significant risk of adverse events. Proper diagnosis is essential to ensure the correct parasitic infection is being treated.

Conclusion

Ivermectin is a powerful antiparasitic agent with a well-established history of treating numerous parasitic infections in humans and animals. Its ability to combat diseases like river blindness, strongyloidiasis, and scabies has had a significant global health impact. It works by targeting specific nerve and muscle channels unique to invertebrates, causing paralysis and death. Despite its broad-spectrum effectiveness, it is essential to use ivermectin under the strict guidance of a healthcare professional and only use products approved for human use. Improper use, particularly with high-concentration animal formulations, can pose serious health risks. Responsible prescribing and public health campaigns have ensured that ivermectin remains a critical tool for managing parasitic diseases worldwide.

For more information on ivermectin and its uses, consult authoritative medical resources such as the National Institutes of Health.

Frequently Asked Questions

Ivermectin treats a wide range of parasites, including internal ones like the threadworm Strongyloides stercoralis (which causes strongyloidiasis) and the microfilariae responsible for onchocerciasis (river blindness) and lymphatic filariasis. It also targets external parasites like scabies mites and head lice.

No, ivermectin is not effective against all worms. While it is highly effective against many nematodes, such as threadworms and microfilariae, it is not effective against parasites like tapeworms. Other medications, such as praziquantel, are needed for tapeworm infections.

Ivermectin kills parasites by binding to and activating their glutamate-gated chloride ion channels. This causes an influx of chloride ions, leading to hyperpolarization of the parasite's nerve and muscle cells, which results in paralysis and death.

No, you should never use ivermectin products intended for animals. Veterinary formulations are much more concentrated and contain ingredients that can be toxic to humans, potentially causing serious side effects, seizures, and even death.

Common side effects can include dizziness, nausea, abdominal pain, diarrhea, and itchy skin. Some side effects, like those associated with river blindness treatment, are actually a reaction to the death of the parasites, known as the Mazzotti reaction.

Yes, ivermectin tablets are FDA-approved for humans to treat intestinal strongyloidiasis and onchocerciasis. Topical versions are approved for treating external parasites like head lice and skin conditions such as rosacea.

For scabies, ivermectin is used in both oral and topical forms. For severe or crusted scabies, or institutional outbreaks, oral treatment may be preferred. While often effective, a single oral dose may be less potent than a topical treatment like permethrin, sometimes requiring repeated dosing.