What are the standard FDA-recommended dosages of ivermectin for onchocerciasis and strongyloidiasis?
Executive summary
The FDA-approved Stromectol (ivermectin) dosing for both intestinal strongyloidiasis and onchocerciasis is centered on a 200 micrograms per kilogram (200 mcg/kg) single oral dose; clinical studies reported cure rates of 64–100% with that single 200‑mcg/kg dose for strongyloidiasis (and the label cites the same 200‑mcg/kg dose for onchocerciasis treatment regimens) [1] [2]. Public guidance notes that onchocerciasis often requires repeated dosing at intervals (3, 6, or 12 months) whereas strongyloidiasis typically uses a single dose with stool follow-up [3] [4].
1. Standard dosages from the FDA label: one weight‑based dose is central
The FDA Stromectol label and subsequent label updates state that a single oral dose providing approximately 200 mcg of ivermectin per kg of body weight was the regimen used in the clinical studies that established the drug’s efficacy for intestinal strongyloidiasis and is the basis for treatment recommendations cited for onchocerciasis [1] [2]. Those label documents explicitly report cure rates of 64–100% following a single 200‑mcg/kg dose in the trials referenced by the manufacturer and FDA [1] [2].
2. Practical differences between indications: single dose vs. repeats
While the dose per administration is the same (200 mcg/kg), guidance for use differs by disease. For uncomplicated intestinal strongyloidiasis, typical practice reflected in drug information is a single 200‑mcg/kg oral dose, with stool exams recommended afterwards to confirm eradication [4] [3]. For onchocerciasis (river blindness), ivermectin targets microfilariae rather than adult worms, so treatment often must be repeated; patient information notes additional doses at 3, 6 or 12 months may be necessary to control the infection [3].
3. How that translates to tablets and patients
Medical‑lay summaries and dosing guides translate the weight‑based dose into tablet counts (for example, 3‑mg tablets) and reiterate the 200‑mcg/kg rule of thumb used for adults and children above weight thresholds; Medical News Today and other summaries repeat that the typical dose for both children and adults is 200 mcg/kg and note a single dose is usually sufficient for strongyloidiasis while onchocerciasis may need repeat dosing [4]. Specific tablet counts for a given weight are calculated from the 200‑mcg/kg figure [4].
4. Safety and follow‑up considerations highlighted in official materials
The Stromectol label warns that ivermectin kills developing microfilariae but not adult Onchocerca volvulus, so adverse reactions (Mazzotti‑type and ocular reactions) associated with onchocerciasis treatment or the disease itself are possible; it also recommends monitoring for treatment effectiveness in strongyloidiasis via repeated stool exams because a single dose may not always clear infection in immunosuppressed patients [1] [2] [4]. Patient information explicitly cautions about dizziness and potential serious reactions in persons with prior or possible loiasis exposure [3].
5. Where sources agree and where nuance remains
All provided sources converge on the same numeric standard: 200 mcg/kg as the key per‑dose figure for both indications [1] [2] [4]. They differ in operational advice: FDA labeling and patient guides emphasize that onchocerciasis may require scheduled repeat doses (3, 6, or 12 months), whereas clinical summaries treat strongyloidiasis as typically a single‑dose illness with follow‑up testing [3] [4]. Available sources do not mention differing FDA‑recommended higher single doses or routine multi‑dose regimens for strongyloidiasis beyond follow‑up and special‑population adjustments (not found in current reporting).
6. Bottom line for clinicians and patients
Use weight to calculate 200 mcg/kg for the initial oral ivermectin dose; for uncomplicated strongyloidiasis that is typically a single administration with post‑treatment stool surveillance, and for onchocerciasis repeat dosing at 3–12 month intervals is commonly needed to control microfilariae—both recommendations are grounded in the FDA label and clinician guidance summarized in the provided sources [1] [2] [3] [4].