What are the standard dosing regimens of ivermectin for common parasitic infections (strongyloidiasis, onchocerciasis, scabies) in adults and children?
Executive summary
Ivermectin dosing for parasitic infections is weight‑based: most authoritative sources report 200 micrograms per kilogram (mcg/kg, 0.2 mg/kg) as the standard single dose for strongyloidiasis and about 150 mcg/kg (0.15 mg/kg) used for onchocerciasis in mass campaigns; scabies regimens commonly use 200 mcg/kg with one or more repeat doses (references: FDA/Mayo Clinic, WHO/NTD guidance, scabies guideline reviews) [1] [2] [3]. Recommendations vary by indication, severity (crusted scabies), patient group, and programmatic use (mass drug administration vs individual therapy) so clinicians routinely adjust interval and repetition [3] [4].
1. How dosing is usually expressed — “mcg/kg” and single doses dominate
Most clinical and regulatory materials express ivermectin dosing as mcg/kg of body weight; for strongyloidiasis the commonly cited regimen is a single 200 mcg/kg oral dose, while onchocerciasis control programmes commonly use a single 150 mcg/kg dose given periodically in mass distribution [1] [2]. Drug information summaries and treatment guidelines therefore convert dosing to the nearest pill count for practical prescribing but always emphasize weight‑based calculation first [1] [5].
2. Strongyloidiasis — standard adult and pediatric dosing
Regulatory summaries and clinical references list single‑dose ivermectin 200 mcg/kg as the standard treatment for intestinal strongyloidiasis in both adults and children who meet weight thresholds (tablets are given to those ≥15 kg) [1] [6]. Immunocompromised patients or those with persistent infection may need repeated or prolonged therapy and specialist follow‑up; sources note monthly suppressive therapy may be considered in difficult cases [6] [7].
3. Onchocerciasis (river blindness) — community and individual use differ
For onchocerciasis, ivermectin is used at approximately 150 mcg/kg as a single dose; in mass drug administration (MDA) programmes that dose is typically given one to four times per year depending on the control/elimination strategy [2]. Clinical summaries and program guidance therefore treat onchocerciasis dosing as lower per dose than for strongyloidiasis but often repeated at community level to reduce transmission [2].
4. Scabies — repeated dosing and severity‑dependent regimens
Oral ivermectin for ordinary scabies is commonly given as 200 mcg/kg with a repeat dose after 7–14 days; several guidelines and reviews list two doses spaced one or two weeks apart as a standard regimen [3]. Crusted or severe scabies requires intensified schedules: published regimens include doses on days 1, 2 and 8, or more extended 3–5+ dose schedules combined with topical therapy [4] [3]. Sources emphasize combining oral ivermectin with topical scabicides when appropriate [3] [8].
5. Children, minimum weight and practical prescribing limits
Most authorities permit the same mcg/kg dosing in children as adults but set a practical lower weight limit (commonly ≥15 kg) for tablet formulations; for example, tablets are indicated for children weighing 15 kg or more and dose must be calculated by weight [1] [6]. Sources note that evidence on very young or low‑weight children is limited and dosing should be handled by pediatric specialists [1].
6. Where guidance diverges — frequency, food effects, and program vs clinic use
Differences across sources arise in repetition timing (7 vs 14 days), use with/without food (some texts advise empty stomach for systemic infections but with food to enhance skin penetration for scabies), and whether ivermectin is framed as the primary option or an alternative to topical agents [5] [3] [9]. WHO and programmatic sources frame onchocerciasis dosing in terms of MDA cycles, while clinical guidelines focus on individual patient regimens [2] [3].
7. Safety caveats, special populations and monitoring
Warnings in prescribing summaries include avoidance or caution in pregnancy and in children below the weight threshold, and attention to rare but serious reactions when treating filarial infections (Mazzotti reactions) and in persons coinfected with Loa loa [1] [7]. Immunocompromised patients with strongyloidiasis may require repeated courses and close monitoring [7] [6].
8. Bottom line for clinicians and patients
Use weight‑based dosing: strongyloidiasis — generally 200 mcg/kg once (repeat or suppressive therapy if needed) [1] [6]; onchocerciasis — typically 150 mcg/kg single dose in control programmes, repeated per MDA schedules [2]; scabies — commonly 200 mcg/kg with a second dose at 7–14 days, and multiple doses for crusted disease often combined with topical therapy [3] [4]. If you need a precise regimen for a specific patient (age, weight, pregnancy status, immunosuppression) consult local guidelines or an infectious‑disease/dermatology specialist because sources show real‑world variation and programmatic exceptions [3] [2].
Limitations: available sources in this set do not provide every country’s label language or all pediatric formulation specifics; for local legal approvals and product leaflets consult national regulators and the manufacturer (not found in current reporting).