What clinical trials have tested ivermectin for parasitic infections beyond approved indications?
Executive summary
Clinical research has tested ivermectin beyond its core approvals (onchocerciasis, strongyloidiasis, and topical formulations for rosacea/head lice) in a range of parasitic contexts — notably scabies, cutaneous larva migrans, various soil‑transmitted helminths and as a mass‑drug‑administration tool aimed at reducing mosquito‑borne transmission — but the public record in the provided reporting names trial types and programmatic studies rather than a definitive catalogue of individually named randomized trials [1] [2] [3]. Major non‑antiparasitic trial efforts (for example COVID‑19) do not support efficacy and have distracted attention and supply away from parasitic indications [4] [5] [6].
1. Clinical work on ectoparasites: scabies, head lice and cutaneous larva migrans
Ivermectin has been widely studied and used off‑label for ectoparasitic conditions such as scabies, head lice (pediculosis) and cutaneous larva migrans; patient care guidelines and drug summaries reference its off‑label clinical use and trials comparing it to topical agents, and clinicians commonly rely on these trial data when prescribing oral ivermectin for such infestations [1] [3] [2]. The sources collectively describe ivermectin’s role as an alternative to topical therapies — for example single or repeated oral dosing for scabies with regimens spaced 7–14 days apart — reflecting randomized and observational studies in dermatology literature even though the provided reporting does not list each trial by registry identifier [1] [3].
2. Trials targeting a broader set of human helminths and filarial diseases
Beyond its FDA‑approved uses, ivermectin figures in clinical research against a broader suite of nematodes and filarial infections — authors and reviews list conditions under investigation or treated clinically with ivermectin including loiasis, trichuriasis, ascariasis, gnathostomiasis and lymphatic filariasis — and these efforts include both controlled trials and programmatic studies often embedded in mass‑drug‑administration (MDA) campaigns [2] [3]. The reporting indicates ivermectin’s inclusion in comparative studies and combination regimens (for example versus or alongside albendazole/mebendazole) but does not supply a comprehensive, sourced list of every randomized trial, so the exact scope and outcome set of those trials cannot be reconstructed from these documents alone [2] [3].
3. Large cluster and programmatic trials: ivermectin to reduce mosquito transmission
A prominent non‑traditional line of clinical research cited is the use of ivermectin in population‑level interventions to reduce mosquito survival after feeding on treated humans — investigations include cluster‑randomized and phase III programmatic trials testing safety and transmission‑reduction impact as a complementary malaria control strategy, with at least one phase III cluster‑randomized study listed in the literature summaries provided [2]. These trials are not seeking to treat human malaria parasites directly but to use ivermectin’s mosquitocidal effect in mass administration to interrupt vector transmission, and the reporting characterizes them as ongoing and under extensive study rather than as mature practice‑changing results [2].
4. How off‑label use and COVID‑era diversion shaped the research landscape
During the COVID‑19 pandemic many small trials and observational studies assessed ivermectin as an antiviral, but well‑conducted randomized trials and systematic reviews cited in the provided reporting found no convincing clinical benefit for COVID‑19, and professional bodies cautioned against off‑label prescribing outside trials because it diverts drug supply from parasitic control and complicates safety monitoring [4] [5] [6]. The surge in prescriptions and public attention — including telehealth prescribing and non‑human formulations being taken by mistake — is documented as having muddied the clinical research environment and raised toxicity concerns even as legitimate parasitology trials continued [7] [8] [6].
5. Limits of the available reporting and where to look next
The sources supplied sketch the landscape — off‑label clinical trials for scabies, cutaneous larva migrans and head lice; comparative helminth studies and MDA/cluster randomized trials for vector control — but do not enumerate or provide registry identifiers for each trial, so a precise, itemized list of all clinical trials testing ivermectin beyond its approved indications cannot be compiled from these documents alone [1] [2]. For a complete, verifiable catalogue, the clinicaltrial.gov registry, WHO ICTRP and recent systematic reviews in parasitology journals should be consulted to retrieve individual randomized‑trial IDs, protocols, and published outcomes.