What is the standard ivermectin dose (mg/kg) for parasitic infections in adults?
Executive summary
The standard, weight‑based oral ivermectin dose used for adult parasitic infections is generally between 150 and 200 micrograms per kilogram (0.15–0.20 mg/kg), most commonly cited as 200 mcg/kg for single‑dose therapy in conditions such as strongyloidiasis and many off‑label parasitic uses [1] [2] [3]. Dosing practices vary by indication—onchocerciasis, strongyloidiasis and scabies have slightly different regimens and repeat‑dose recommendations—so the precise mg/kg used clinically depends on the parasite targeted and product labeling [4] [1] [2].
1. The headline figure: 150–200 mcg/kg is the conventional range
Regulatory and clinical references converge on a narrow range: some sources report a standard single oral dose of about 150 mcg/kg while others and the manufacturer’s label are designed to provide approximately 200 mcg/kg (0.2 mg/kg) per dose, making 0.15–0.20 mg/kg the practical standard used in adults [4] [1] [2].
2. Indication matters: single‑dose for strongyloidiasis and repeated programs for onchocerciasis
For intestinal strongyloidiasis, a single dose of roughly 200 mcg/kg is commonly recommended and is FDA‑approved for adults and children ≥15 kg, though follow‑up stool exams are advised to document cure [5] [1]. For onchocerciasis (river blindness), ivermectin reduces microfilariae and programs commonly use single doses in the same 150–200 mcg/kg range, but repeated mass‑treatment or retreatment at intervals is required because the drug does not reliably kill adult worms [4] [1].
3. Scabies and dermatologic uses: timing and repeat dosing differ
Scabies regimens often use 200 mcg/kg as the oral dose and frequently call for repetition (commonly at 7–14 days) or multiple doses for crusted scabies; dermatology references also note ivermectin’s use for Demodex‑related conditions and rosacea in topical formulations, but systemic regimens for skin parasites typically center on 0.2 mg/kg with repeat dosing as needed [2] [6] [7].
4. Product strengths, administration and practical dosing
Commercial tablet packs (Stromectol) and dosing tables translate weight‑based mcg/kg dosing into 3 mg tablet counts by weight bands, and manufacturers instruct taking tablets on an empty stomach for some indications; the label is intended to provide approximately 200 mcg/kg and states additional doses are usually unnecessary for single‑episode intestinal infections [1] [8] [4].
5. Safety caveats and special‑population alerts
Higher ivermectin doses have been explored in trials and for vector control, but increased dose can correlate with more adverse events and rare serious reactions occur—especially in people co‑infected with Loa loa where rapid parasite kill can cause severe encephalopathy—so screening or geographic risk assessment is recommended before mass administration in endemic areas [3] [8] [9]. Liver metabolism and drug interactions can influence use in hepatic disease and the elderly, and product literature stresses clinician supervision and follow‑up testing [10] [8].
6. Where guidance diverges and why clinicians choose different numbers
Variability in the cited “standard” dose (150 mcg/kg vs 200 mcg/kg, and occasional broader ranges like 0.15–0.25 mg/kg) reflects differences in historical trial dosing, indication‑specific efficacy data, manufacturer labeling, and pragmatic public‑health dosing strategies; clinical guidance therefore balances efficacy data, safety concerns and operational simplicity when recommending 0.15–0.20 mg/kg for adults [1] [2] [3].
7. Bottom line for adult parasitic infections
The authoritative and practical answer: weight‑based oral ivermectin for most adult parasitic infections is dosed at about 150–200 micrograms per kilogram (0.15–0.20 mg/kg), with 200 mcg/kg frequently used as the standard single dose for strongyloidiasis and many scabies regimens, while programmatic onchocerciasis treatment uses the same range but requires repeat treatments because adult worms persist [1] [2] [4].