What are the approved human dosing regimens of ivermectin for specific parasitic diseases (mg/kg) and how are they determined?
Executive summary
Ivermectin dosing in humans is disease-specific and weight‑based: standard microgram-per-kilogram regimens range from about 150–200 µg/kg for onchocerciasis, strongyloidiasis and enterobiasis, to 400 µg/kg (0.4 mg/kg) used in lymphatic filariasis programs, with scabies typically treated with 200 µg/kg repeated as needed [1] [2] [3] [4]. Those regimens rest on decades of clinical trials, mass‑drug administration experience, pharmacokinetic modeling and regulatory labeling rather than a single universal rule, and important caveats apply for children under 15 kg, pregnant women, and settings with Loa loa risk [5] [6] [7].
1. Approved regimens by disease — the headline numbers
For FDA- and guideline-recognized human indications, the commonly cited single‑dose regimens are approximately 150–200 µg/kg for onchocerciasis, strongyloidiasis and enterobiasis, with regulatory labels and reviews commonly referencing 200 µg/kg as an effective single dose for many intestinal helminths [1] [5] [2]. Lymphatic filariasis programs use higher annual doses—0.4 mg/kg (400 µg/kg) in combination strategies or alongside other drugs in mass campaigns—derived from large field studies [1] [3]. Scabies therapy is not FDA‑approved for oral ivermectin but clinical guidance recommends 200 µg/kg per dose, typically given as two doses 7–14 days apart or multi‑dose schedules for crusted or severe disease [4].
2. How those numbers were derived — trials, programs and pharmacology
Dosing recommendations emerged from a mix of randomized and open‑label clinical trials, large population mass‑drug administration campaigns, and pharmacokinetic/pharmacodynamic analyses; for example, onchocerciasis and intestinal helminth dosing comes from comparative clinical studies showing cure rates with single 150–200 µg/kg doses and from post‑marketing data summarized in regulatory labels [5] [1]. For public‑health uses like lymphatic filariasis, regimen selection reflected large field trials and operational studies (including combinations with diethylcarbamazine or albendazole) that balanced efficacy against community safety and logistics, producing annual 0.4 mg/kg schedules used in endemic regions [3] [8]. Contemporary dose‑finding and transmission‑reduction work also uses pharmacokinetic modeling and Monte Carlo simulation to refine regimens for novel goals such as vector mortality or malaria control [9].
3. Practical administration — frequency, formulation and program context
Ivermectin is given orally, weight‑based, usually as a single dose on an empty stomach for many helminth infections, but repeat dosing is common: scabies guidance recommends repeated 200 µg/kg doses and mass campaigns repeat ivermectin at 3–12 month intervals depending on program goals [2] [4]. New fixed‑dose combinations (ivermectin plus albendazole in orodispersible tablets) were approved based on trials showing improved efficacy for soil‑transmitted helminths, offering standardized tablet strengths (e.g., 9 mg or 18 mg ivermectin with 400 mg albendazole) to simplify dosing in endemic populations [8].
4. Safety, special populations and monitoring
Safety data support ivermectin’s favorable profile at standard doses, but limitations exist: pediatric safety is not established for children under 15 kg, elderly or liver‑impaired patients require caution, and adverse inflammatory reactions can result from parasite kill (Mazzotti reactions) or interactions with other drugs via P‑glycoprotein pathways [6] [3] [10]. Programs in Loa loa–endemic areas must screen carefully because high microfilarial loads can produce severe adverse events when microfilaricidal drugs are given [7].
5. Uncertainties, off‑label uses and contested claims
Evidence is robust for parasitic indications but not for many high‑profile off‑label claims: regulatory and clinical sources emphasize that ivermectin is approved for specific parasitic diseases (and for topical rosacea in some jurisdictions) and that it is not approved for COVID‑19 or other unproven indications—warnings reiterated by drug information and public‑health authorities [11] [2]. Dose escalation studies and experimental regimens (e.g., high‑dose or prolonged schedules) are ongoing for special aims such as reducing malaria transmission, but those are research protocols rather than standard care and require careful safety monitoring [9].
6. Bottom line — tailored, evidence‑based, weight‑based
The approved human dosing landscape for ivermectin is not a single mg/kg figure but a set of weight‑based regimens chosen to balance parasite susceptibility, host safety and public‑health practicality: roughly 150–200 µg/kg for many individual helminth infections, 200 µg/kg repeated for scabies, and 400 µg/kg used in mass filariasis programs—each derived from clinical trials, large field studies and pharmacokinetic modeling and subject to contraindications and programmatic caveats in certain populations [1] [2] [3] [4].