What are typical ivermectin concentrations in human oral tablets compared to veterinary formulations?
Executive summary
Human oral ivermectin tablets approved for parasitic infections are dosed by body weight and typically use single doses of about 0.15–0.20 mg/kg (FDA‑approved ranges are cited in aggregated review) for specific indications; by contrast, veterinary products—especially large‑animal pastes, injectables and drenches—are manufactured at much higher concentrations and are intended to deliver total milligram amounts many times higher for livestock, which has driven toxic exposures when people used animal formulations [1] [2] [3].
1. Human tablets: low milligram-per-kilogram, prescription‑level dosing
Approved human oral ivermectin products are manufactured for weight‑based dosing: the commonly referenced therapeutic single dose for some human parasitic infections is roughly 0.15–0.20 mg per kilogram of body weight, given as a tablet formulation under medical supervision [1] [4]. Medical and drug information guides warn that human formulations are intended for specific parasitic diseases and that there is no FDA approval for use against COVID‑19 [4] [2].
2. Veterinary formulations: concentrated, species‑and‑route specific
Veterinary ivermectin exists as pastes, injectables, pour‑ons, drenches and chewables formulated for animals ranging from small pets to horses and cattle. These products are manufactured to deliver much larger absolute doses appropriate for large animals; for example, equine pastes commonly list concentrations (e.g., 1.87% paste) and are designed to give tens to hundreds of milligrams to horses—amounts that far exceed human tablet doses on a per‑dose basis [5] [3]. Regulatory and veterinary sources document that livestock doses can be many times the dosage used in humans [3].
3. Why concentration and intended dose differ: species, weight and route
Ivermectin dose decisions reflect the treated species’ body mass, parasite targets, and administration route. Human tablets are calibrated for human pharmacology and safety margins at therapeutic mg/kg ranges; veterinary formulations are optimized to treat much heavier animals or to use different delivery methods (topical, injectable, oral pastes) and so contain higher concentrations or different presentations to achieve the necessary mg/kg for that species [6] [5].
4. Real‑world harm when people use animal products
Public health reporting and poison‑control data show overdoses and toxicity occurred when people took veterinary ivermectin meant for livestock. During the COVID‑19 period, poison centers reported neurological and gastrointestinal adverse events after ingestion of veterinary products; the FDA and media urged against using animal ivermectin in humans because the concentrations and dosing regimens differ and can cause harm [3] [2]. Veterinary literature also records overdose cases when large‑animal formulations were given to species for which they were not approved [7].
5. Pharmacology and toxicity context: how big is the gap?
Pharmacological reviews and summaries place approved human single‑dose ranges (≈0.15–0.20 mg/kg) well below doses estimated to cause serious effects: one review noted that in vitro antiviral effects required very high equivalent oral doses (an estimate cited at ~7.0 mg/kg for 50% SARS‑CoV‑2 inhibition) and that experimental LD50 estimates in animals translate to human‑equivalent ranges far above routine human dosing [1]. Those comparisons underline why large‑animal products—which deliver much higher total milligrams—can produce toxic exposures in people [1].
6. What the sources do and do not say (limitations and disagreements)
Sources consistently state human tablets are prescribed by weight and that animal products can be many times higher in dose than human regimens; they uniformly advise against using veterinary ivermectin for people [4] [3] [2]. Available sources do not provide a single tabulated comparison of tablet milligram strengths versus every veterinary product’s concentration in this set of documents; they do, however, give examples (e.g., 1.87% horse paste) and general warnings about higher livestock dosing [5] [3]. Some review pieces quantify human approved single‑dose ranges versus experimental toxic thresholds [1], but detailed mg-per‑tablet inventories across brands are not provided in the available reporting.
7. Practical takeaway: don’t substitute animal formulations for human tablets
Regulatory and clinical sources agree: human ivermectin tablets are formulated and dosed for people and should be used only as prescribed; veterinary formulations are concentrated for animals and have caused overdoses when misused by people [2] [3] [7]. If you are comparing products, consult a clinician or pharmacist rather than extrapolating from a livestock paste label—the risks of neurological or systemic toxicity are documented when the wrong formulation is taken by humans [3] [2].