What are the approved human medical uses and recommended dosages of ivermectin?

1. What ivermectin is and the conditions it is approved to treat

Ivermectin is a broad‑spectrum antiparasitic (macrocyclic lactone) used in human medicine since the late 1980s to treat several worm infections and infestations; approved indications for oral ivermectin include onchocerciasis (river blindness), strongyloidiasis and other helminth infections, while topical formulations are approved for conditions such as rosacea and head lice ^{[1] [7] [5] [6] [3]}.

2. Standard recommended dosages for approved oral indications

For systemic parasitic infections the dose is weight‑based and determined by a clinician, with commonly used single doses around 150–200 micrograms per kilogram of body weight (often given as a single dose and in some programs repeated at intervals from months to a year depending on the disease) — this 0.15–0.20 mg/kg range is the conventional FDA‑referenced dosing for many indications ^{[2] [3] [1]}. Clinical trials and mass‑drug administration programs historically have used these weight‑based single doses for onchocerciasis and lymphatic filariasis control ^{[1] [8]}.

3. Topical products, formulations and routes of administration

Only oral and topical formulations are approved for human use; topical ivermectin creams are licensed for dermatologic uses such as rosacea and certain lice/scabies indications, while injectable and many parenteral formulations are intended for veterinary use and are not approved in people (oral administration is the only approved systemic route for humans) ^{[9] [5] [4]}.

4. Safety profile, adverse effects and important cautions

Ivermectin has a long safety record in humans with minimal side effects at approved doses and has been used safely in mass campaigns, but side effects and allergic reactions do occur and elderly patients or those with liver, kidney or interacting medications may need caution or dose adjustment ^{[8] [2]}. Higher‑dose human studies show tolerability up to much larger multiples of the standard dose, but that does not mean higher dosing is routinely recommended; moreover, taking veterinary products formulated for animals has caused serious toxicities and hospitalizations and is explicitly warned against by regulators ^{[1] [3] [4] [6] [5]}. Drug interactions that alter P‑glycoprotein transport or CYP3A4 metabolism can increase ivermectin exposure and merit monitoring or avoidance of combinations ^{[10] [7]}.

5. The COVID‑19 controversy and the evidence boundaries

Laboratory studies showed ivermectin can inhibit SARS‑CoV‑2 in vitro, but the concentrations required exceed those achievable with standard approved dosing, and regulators (including the FDA and major health agencies) have not authorized ivermectin for COVID‑19 because clinical evidence is inconsistent and insufficient; some small trials have reported possible signals but are limited and do not establish efficacy for prevention or treatment at approved doses ^{[3] [4] [11] [12]}. Major reviews and public health statements therefore recommend against routine use for COVID‑19 outside properly conducted clinical trials ^{[3] [4]}.

6. Practical bottom line for clinicians and public health

Prescribed ivermectin for approved human indications should follow weight‑based dosing (commonly 150–200 mcg/kg single dose for many parasitic infections) and use human‑approved oral or topical products under medical supervision; off‑label high‑dose use or self‑medication with animal formulations is unsafe and not supported by regulators or by the current clinical evidence base for non‑parasitic uses such as COVID‑19 ^{[2] [5] [4] [1]}.