Maximum Dose of Ivermectin
The standard maximum dose of ivermectin is 200 μg/kg per administration, with the FDA-approved label specifying this dose for strongyloidiasis and 150 μg/kg for onchocerciasis in patients weighing ≥15 kg. 1
Standard Dosing Parameters
For adults and children ≥15 kg: The routinely recommended dose is 200 μg/kg for most parasitic indications including strongyloidiasis, scabies, and most helminth infections 2, 3, 1
Weight-based tablet dosing (using 3 mg tablets) follows FDA guidelines: 1
- 15-24 kg: 1 tablet (3 mg)
- 25-35 kg: 2 tablets (6 mg)
- 36-50 kg: 3 tablets (9 mg)
- 51-65 kg: 4 tablets (12 mg)
- 66-79 kg: 5 tablets (15 mg)
- ≥80 kg: 200 μg/kg calculated dose
Higher Doses in Specific Clinical Contexts
While 200 μg/kg represents the standard maximum, certain conditions warrant higher or more frequent dosing:
Lymphatic Filariasis
- 400 μg/kg is the recommended dose, representing the highest single-dose indication 4
Crusted (Norwegian) Scabies
- Intensified regimen: 200 μg/kg on days 1,2,8,9, and 15 (not a higher single dose, but more frequent administration) 2, 5
- Additional doses on days 22 and 29 may be required for severe cases 2
- This represents multiple standard doses rather than exceeding 200 μg/kg per administration 5
Loiasis Treatment
- Some guidelines describe 200 μg/kg daily for up to 10 days in endemic settings, though this is controversial 6
- Most guidelines recommend single doses of 150-200 μg/kg with monthly, quarterly, or biannual repetition rather than higher single doses 6
Pediatric Considerations
- Children ≥15 kg: Standard 200 μg/kg dose applies 2, 1
- Children <15 kg: Not FDA-approved, but observational data supports safety at 200-300 μg/kg 7
- Pharmacokinetic modeling suggests children aged 2-5 years may require 300 μg/kg and those aged 6-12 years may need 250 μg/kg to achieve equivalent exposure to adults receiving 200 μg/kg, due to higher clearance rates 8
- For infants 3-24 months, weight-based tablet fractions (0.75-3 mg total) are being evaluated 9
Safety Thresholds
- Doses up to 300 μg/kg have been studied and appear safe in mass treatment campaigns, with the rationale that overdosing is safer than underdosing 10
- 400 μg/kg for lymphatic filariasis is the highest routinely recommended single dose, though it carries increased risk of ocular adverse events 4
- The FDA label notes that ivermectin has been tested at doses "well in excess of the standard dose" without prohibitive toxicity 1
Critical Caveats
- Loa loa co-infection: Patients with high Loa loa microfilaremia (>8,000-30,000 mf/mL) risk fatal encephalopathy with ivermectin; pretreatment assessment is mandatory for those with West/Central African exposure 6, 1
- Onchocerciasis co-infection: Diethylcarbamazine is contraindicated; ivermectin dosing must be carefully considered 6
- Pregnancy: Category C; not recommended as safety is not established, though limited data suggest low risk 1
- Children <15 kg: Off-label use; safety data are limited but accumulating 2, 7
Administration Requirements
- Take with food: Bioavailability increases approximately 2.5-fold when taken with a substantial meal (preferably high-fat); empty stomach reduces absorption by ~60% 5, 1
- No renal dose adjustment required regardless of creatinine clearance 5
- Caution in severe hepatic impairment: Safety of repeated dosing is uncertain 5
In summary, 200 μg/kg represents the standard maximum dose for routine indications in patients ≥15 kg, with 400 μg/kg reserved specifically for lymphatic filariasis. 1, 4 Higher doses (300 μg/kg) may be appropriate in children to achieve equivalent exposure, but this remains investigational. 8