What are the recommended therapeutic doses of ivermectin for approved indications and how are they determined?
Executive summary
Approved human doses of oral ivermectin for parasitic diseases are weight‑based and generally center on about 200 micrograms/kg as a single dose (e.g., 200 mcg/kg) for strongyloidiasis and onchocerciasis; topical formulations (0.5–1%) are approved for lice and rosacea [1] [2]. Dose selection historically relies on randomized clinical trials, pharmacokinetics, efficacy against parasite stages and safety margins established in labels and reviews [3] [4].
1. What “approved” ivermectin dosing looks like in practice
For systemic human indications the commonly cited regimen is a single, body‑weight–based oral dose of about 200 micrograms per kilogram (200 mcg/kg), with tablet strengths of 3 mg used to achieve that target [1] [3]. Topical products include ivermectin 0.5% lotion for head lice and 1% cream for rosacea; those concentrations are the approved, marketed strengths [2]. Authoritative drug monographs and prescribing labels list these indications and dose schemes [1] [3].
2. How regulators and clinicians determine those doses
Regulatory labels and clinical dosing arise from clinical trials showing cure or suppression of parasitic infections, supported by pharmacokinetic (PK) and toxicology data that establish achievable plasma exposures and safety margins. The Stromectol (ivermectin) label states the 200 mcg/kg regimen and notes animal toxicology and human clinical cure rates as part of its approval rationale [3]. Reviews of ivermectin’s pharmacology and decades of clinical experience in dermatology and tropical medicine summarize how PK, efficacy against parasite life stages and tolerability inform dosing [4].
3. Why some groups propose much higher “therapeutic” doses (and the limits of that evidence)
Since 2020 and into 2025, off‑label and experimental uses — notably for COVID‑19 and more recently cancer in social‑media and small case‑report compilations — have pushed much higher or prolonged ivermectin regimens, sometimes measured in mg/kg rather than mcg/kg (examples include suggested doses up to 1 mg/kg/day or other high regimens in non‑peer venues) [5] [6]. These proposals are usually grounded in in vitro activity, preclinical cancer models or patient testimonials rather than large, randomized human trials; pharmacokinetic analyses show concentrations effective in cell culture often exceed those safely achieved in humans at approved doses [7] [8]. Systematic, regulatory endorsement of high‑dose use is absent in the sources provided [9].
4. Safety and monitoring concerns when doses exceed approved ranges
Regulatory and clinical reviews warn that high or prolonged dosing raises risk: ivermectin interacts with other drugs via P‑glycoprotein transport, can potentiate drug interactions (notably with agents affecting P‑gp), and in high doses has been associated with central‑nervous‑system toxicity such as confusion, visual disturbance, seizures and in worst cases coma reported by regulators [10] [4] [11]. The FDA and treatment‑guideline sources note hospitalizations and poisonings after inappropriate use of veterinary products or self‑medication and explicitly state ivermectin is not FDA‑authorized for conditions like COVID‑19 [9] [7].
5. Where evidence is evolving — cancer and repurposing claims
Multiple 2024–2025 preclinical studies and early phase trials are reported or compiled in advocacy and specialty sites suggesting anticancer mechanisms and early human case reports, and at least one phase I/II trial pairing ivermectin with an immunotherapy was presented at ASCO 2025 per these compilations [5] [12]. However, much of the cancer advocacy material is case‑report compilations, preprints or non–peer‑reviewed summaries; independent reviews caution about misinformation and call for rigorous trials before clinical adoption [13] [5]. Available sources do not mention regulatory approval of ivermectin for cancer or detailed, consensus high‑dose safety data from large trials.
6. Practical takeaways and reporting caveats
If you need dosing for approved indications, use established, weight‑based regimens (≈200 mcg/kg oral single dose) and approved topical concentrations for dermatologic uses; those are documented in label information and clinical monographs [1] [2] [3]. Claims for much higher “therapeutic” doses for cancer or viral disease are largely supported by preclinical work, anecdote, or non‑peer sources and lack regulatory endorsement; experts and regulators warn about toxicity and drug interactions with unsupervised higher dosing [5] [6] [11] [9]. My reporting is limited to the sources you provided; wider regulatory documents or later peer‑reviewed trials might change this picture but are not contained in the supplied material.