Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
IVERMECTIN vs ERGAMISOL
Clinician-reviewed, head-to-head comparison of mechanism, dosing, pharmacokinetics, and safety profiles.
Last clinically reviewed: July 2026 · OpiCalc Medical Review Team
Ivermectin is a macrocyclic lactone that binds selectively and with high affinity to glutamate-gated chloride ion channels in invertebrate nerve and muscle cells, leading to increased chloride ion influx, hyperpolarization, and paralysis of the parasite. It also interacts with other ligand-gated chloride channels, such as those gated by gamma-aminobutyric acid (GABA). In mammals, these channels are largely confined to the central nervous system, but ivermectin does not readily cross the blood-brain barrier, providing a safety margin.
Levamisole is an anthelmintic and immunomodulator. It acts as a nicotinic acetylcholine receptor agonist at the neuromuscular junction in nematodes, causing spastic paralysis. Its immunomodulatory effects are thought to involve stimulation of T-cell activation and phagocytosis.
FDA-approved: Treatment of onchocerciasis (river blindness), strongyloidiasis, and intestinal infections caused by Strongyloides stercoralis.,FDA-approved: Scabies (topical formulation).,Off-label: Treatment of other parasitic infections including ascariasis, trichuriasis, enterobiasis, filariasis, loiasis, and cutaneous larva migrans.,Off-label: Treatment of severe, refractory, or crusted scabies (oral).,Off-label: Used in combination with albendazole for lymphatic filariasis.,Investigational: Used for scabies in institutional settings and for rosacea (topical).
Adjuvant therapy in combination with fluorouracil for the treatment of Dukes' C colon cancer (FDA-approved, now discontinued),Off-label: treatment of steroid-resistant nephrotic syndrome in children, and as an adjuvant in melanoma and other cancers
150–200 mcg/kg orally once, with repeat dose in 2 weeks for strongyloidiasis; for scabies, 200 mcg/kg orally once, repeat in 2 weeks if needed.
150 mg orally once daily
Terminal elimination half-life is approximately 18 hours (range 12-24 hours) in healthy adults; prolonged in hepatic impairment.
2-4 hours (terminal); prolonged in hepatic impairment (up to 8-12 hours) and renal impairment (increase by 1.5- to 2-fold).
Ivermectin is primarily metabolized in the liver by the cytochrome P450 enzyme CYP3A4. It is also a substrate of P-glycoprotein (P-gp).
Hepatic metabolism primarily via CYP450 enzymes (CYP2B6 and CYP3A4) to active metabolites. Levamisole undergoes extensive biotransformation to its major metabolites, p-hydroxy-levamisole and levamisole sulfoxide.
Primarily fecal (≥90% as unchanged drug and metabolites); renal excretion is minimal (<1% of dose). Biliary excretion contributes to fecal elimination.
Renal (parent drug and metabolites): ~70% in urine; Fecal: ~25% primarily as metabolites; <5% unchanged in urine.
Approximately 93% bound to plasma proteins, primarily albumin and possibly alpha-1-acid glycoprotein.
20-30%, primarily to albumin.
Apparent volume of distribution is 3.1-3.5 L/kg (large, indicating extensive tissue distribution including fat and skin).
1.0-1.5 L/kg; indicates extensive tissue distribution, including penetration into liver and kidneys.
Oral bioavailability is approximately 60-80% (due to extensive first-pass metabolism). Topical bioavailability is negligible (<1% systemic absorption).
Oral: 40-60% (extensive first-pass metabolism).
No dose adjustment required for any degree of renal impairment.
GFR 30-60 m L/min: no adjustment; GFR <30 m L/min: not recommended
Use with caution in severe hepatic impairment; specific Child-Pugh-based dosing not established.
Child-Pugh A: no adjustment; Child-Pugh B or C: avoid use
Weight-based: 150–200 mcg/kg orally once, same as adult; safety for children weighing less than 15 kg not established.
2.5 mg/kg orally once daily; maximum 150 mg daily
No specific dose adjustment; monitor for adverse effects due to potential age-related organ dysfunction.
No specific adjustment; monitor for renal function and potential QT prolongation
No FDA black box warnings.
None specifically required for ergamisol (levamisole). However, use of levamisole as an immunomodulator has been associated with agranulocytosis and other severe hematologic reactions.
Severe skin reactions (Mazzotti reaction) when treating onchocerciasis, including pruritus, urticaria, fever, arthralgias, syncope, and lymphadenitis.,Neurological toxicity in high doses or with compromised blood-brain barrier (e.g., due to meningitis, African trypanosomiasis, or Loa loa infection with high microfilarial loads).,Ocular reactions in onchocerciasis: exacerbation of eye lesions, including optic neuritis and chorioretinitis.,Potential for drug interactions with CYP3A4 inhibitors (e.g., ketoconazole, erythromycin) or P-gp inhibitors (e.g., verapamil, cyclosporine), leading to increased ivermectin exposure.,Hypersensitivity reactions.,Use in pregnancy only if clearly needed (data limited).,Not recommended in children under 5 years of age or weighing less than 15 kg.
Agranulocytosis (may occur weeks after initiation and is reversible upon discontinuation), hemolytic anemia (especially in patients with G6PD deficiency), neurologic effects (seizures, dizziness, headache), hepatotoxicity, and hypersensitivity reactions.
Hypersensitivity to ivermectin or any component of the formulation.,Concurrent use with drugs that inhibit CYP3A4 or P-gp may require caution, but absolute contraindication is rare.,Loa loa infection with high microfilarial loads (risk of severe encephalopathy).
Known hypersensitivity to levamisole; patients with a history of agranulocytosis induced by levamisole; concomitant use with alcohol (disulfiram-like reaction); caution in patients with hepatic or renal impairment.
Ivermectin should be taken on an empty stomach with water. Administration with food, particularly high-fat meals, can significantly increase absorption (up to 2.5-fold), potentially increasing the risk of adverse effects. Therefore, avoid food for at least 2 hours before and 1 hour after dosing. Grapefruit juice may inhibit CYP3A4 and could theoretically increase ivermectin levels; caution is advised.
Avoid alcohol during therapy due to potential disulfiram-like reaction (nausea, vomiting, flushing). No specific food restrictions; maintain adequate hydration. Grapefruit juice may inhibit CYP2C19 metabolism, potentially increasing levamisole levels; consider avoidance.
FDA Category C. Animal studies show teratogenicity at high doses. Human data limited; avoid in first trimester unless benefit outweighs risk. No increased malformation risk in second/third trimester from observational studies.
Ergamisole (levamisole) is classified as FDA Pregnancy Category C. Animal studies have shown embryotoxicity and teratogenicity at doses comparable to human doses. There are no adequate and well-controlled studies in pregnant women. Use only if potential benefit justifies potential risk to fetus. In first trimester, avoid use; second and third trimester, use with caution if indicated.
Ivermectin is excreted into breast milk; M/P ratio unknown. Limited human data suggests low levels. Caution in infants weighing <15 kg due to potential CNS effects. Consider temporary cessation of breastfeeding during therapy.
Levamisole is excreted in human milk in low amounts; M/P ratio is not established. Because of potential for serious adverse reactions in nursing infants, a decision should be made whether to discontinue nursing or discontinue the drug, taking into account the importance of the drug to the mother.
Pharmacokinetics in pregnancy not well studied. No recommended dose adjustments. Use standard weight-based dosing (150–200 mcg/kg) but avoid in first trimester unless essential.
Pharmacokinetics in pregnancy are not well characterized. No specific dose adjustments are recommended; however, due to potential for altered metabolism, use lowest effective dose and monitor maternal toxicity closely.
Ivermectin is a broad-spectrum antiparasitic agent that causes parasite death by increasing chloride ion conductance in invertebrate nerve and muscle cells. It is the drug of choice for onchocerciasis and strongyloidiasis, and is also used for scabies and head lice. For onchocerciasis, it is given as a single dose of 150 mcg/kg, repeated every 6-12 months. For strongyloidiasis, the recommended dose is 200 mcg/kg daily for 2 days. For crusted scabies, multiple doses (e.g., on days 1, 2, 8, 9) may be required. Note: Ivermectin does not kill adult Onchocerca worms but reduces microfilarial load. Severe adverse effects (Mazzotti reaction) can occur in onchocerciasis due to rapid microfilarial killing. Avoid in patients with Loa loa co-infection due to risk of encephalopathy. Ivermectin is not recommended for children under 15 kg or pregnant women unless benefits outweigh risks. Drug interactions: caution with CYP3A4 inhibitors or inducers; consider dose adjustment with strong inhibitors like ketoconazole.
Levamisole (ERGAMISOL) is primarily used as an immunomodulator in adjuvant therapy for stage III colon cancer after surgical resection. It is often combined with fluorouracil. Monitor for agranulocytosis, especially in patients with poor metabolizer status of CYP2D6. Agranulocytosis can occur weeks to months after initiation; obtain baseline CBC and repeat periodically. Levamisole can cause a metallic taste and reversible ANCA-positive vasculitis. Avoid in patients with known hypersensitivity or bone marrow depression.
Take ivermectin exactly as prescribed, usually on an empty stomach with water.,For strongyloidiasis or scabies, you may need a second dose; complete the full course.,Do not take with food, especially high-fat meals, as they may increase absorption and risk of side effects.,Common side effects include dizziness, pruritus, and gastrointestinal upset.,Report any severe skin rash, swelling, or difficulty breathing immediately.,If being treated for onchocerciasis, you may experience a reaction (fever, itching, joint pain) due to dying parasites; this is usually mild and treatable.,Avoid driving or operating machinery if you experience dizziness or drowsiness.,Inform your doctor if you are pregnant, breastfeeding, or taking other medications.,Do not use ivermectin for COVID-19; it is not approved for viral infections.
Take levamisole exactly as prescribed, usually for 3 days every 2 weeks for 1 year. Do not miss doses.,Report any signs of infection (fever, sore throat, mouth sores) immediately as it can lower white blood cell count.,You may experience a metallic taste; this is harmless and may resolve with time.,Avoid alcohol consumption as it may increase risk of adverse effects.,Inform your doctor if you are pregnant, planning to become pregnant, or breastfeeding.,Do not take any other medications or supplements without consulting your doctor.
"Coadministration of ivermectin, a known inhibitor of cytochrome P450 3A4 (CYP3A4), with netupitant, a CYP3A4 substrate, can result in increased systemic exposure to netupitant. This may potentiate netupitant-related adverse effects, such as nausea, fatigue, and QT prolongation, particularly in patients with underlying hepatic impairment or those receiving other QT-prolonging agents."
"Ivermectin is a substrate of CYP3A4 and P-glycoprotein (P-gp), while imatinib is primarily metabolized by CYP3A4 and is also a substrate of P-gp. Concomitant administration of ivermectin may competitively inhibit CYP3A4 and P-gp, reducing the clearance of imatinib and increasing its systemic exposure. This can potentiate imatinib's adverse effects, including hepatotoxicity, fluid retention, and myelosuppression, particularly at high doses."
"Ivermectin is a moderate inhibitor of CYP3A4, the primary enzyme responsible for simeprevir metabolism. Concomitant administration significantly reduces simeprevir clearance, leading to elevated plasma concentrations. This increases the risk of simeprevir-related adverse effects, including hepatotoxicity, QT prolongation, and rash."
No interactions on record
Explore head-to-head clinical comparisons of other medications in the same therapeutic classes.
Common clinical questions about IVERMECTIN vs ERGAMISOL, answered by our medical review team.
IVERMECTIN is a Anthelmintic that works by Ivermectin is a macrocyclic lactone that binds selectively and with high affinity to glutamate-gated chloride ion channels in invertebrate nerve and muscle cells, leading to increased chloride ion influx, hyperpolarization, and paralysis of the parasite. It also interacts with other ligand-gated chloride channels, such as those gated by gamma-aminobutyric acid (GABA). In mammals, these channels are largely confined to the central nervous system, but ivermectin does not readily cross the blood-brain barrier, providing a safety margin.. ERGAMISOL is a Anthelmintic Immunomodulator that works by Levamisole is an anthelmintic and immunomodulator. It acts as a nicotinic acetylcholine receptor agonist at the neuromuscular junction in nematodes, causing spastic paralysis. Its immunomodulatory effects are thought to involve stimulation of T-cell activation and phagocytosis.. They differ in pharmacokinetic profiles, FDA-approved indications, and side effect profiles.
Potency comparisons between IVERMECTIN and ERGAMISOL depend on the specific clinical indication. These are agents from distinct pharmacological classes and are not directly interchangeable by dose. A physician or clinical pharmacist should guide any therapeutic switching decisions.
The standard adult dose of IVERMECTIN is: 150–200 mcg/kg orally once, with repeat dose in 2 weeks for strongyloidiasis; for scabies, 200 mcg/kg orally once, repeat in 2 weeks if needed.. The standard adult dose of ERGAMISOL is: 150 mg orally once daily. Dosing should always be individualized based on indication, renal and hepatic function, age, and other patient factors.
No direct drug-drug interaction has been formally documented between IVERMECTIN and ERGAMISOL in current clinical databases. However, individual patient risk factors including other medications, organ function, and comorbidities should always be evaluated by a qualified healthcare provider.
The maternal-fetal safety profiles differ. IVERMECTIN is classified as Category A/B. FDA Category C. Animal studies show teratogenicity at high doses. Human data limited; avoid in first trimester unless benefit outweighs risk. No increased malformation risk in seco. ERGAMISOL is classified as Category C. Ergamisole (levamisole) is classified as FDA Pregnancy Category C. Animal studies have shown embryotoxicity and teratogenicity at doses comparable to human doses. There are no adeq. Always consult a maternal-fetal medicine specialist before taking either drug during pregnancy or lactation.