Ivermectin: FDA-Approved Indications and Dosing
Ivermectin is FDA-approved exclusively for two parasitic infections: intestinal strongyloidiasis and onchocerciasis, with no proven therapeutic utility for other conditions including COVID-19 or cancer. 1
FDA-Approved Indications
Strongyloidiasis (Intestinal)
- Indication: Treatment of nondisseminated strongyloidiasis caused by Strongyloides stercoralis 1
- Efficacy: Clinical studies demonstrate 64-100% cure rates following a single dose 1
Onchocerciasis
- Indication: Treatment of onchocerciasis caused by Onchocerca volvulus 1
- Important limitation: Ivermectin has NO activity against adult Onchocerca volvulus parasites; it only targets microfilariae 1
- Surgical consideration: Nodulectomy may be considered to eliminate adult parasites producing microfilariae 1
Dosing Regimens
For Strongyloidiasis
- Dose: Single oral dose of 200 mcg/kg body weight 1
- Administration: Take on an empty stomach with water 1
- Follow-up: Perform stool examinations to verify eradication; additional doses generally not necessary 1
Weight-based dosing table: 1
- 15-24 kg: 1 tablet (3 mg)
- 25-35 kg: 2 tablets
- 36-50 kg: 3 tablets
- 51-65 kg: 4 tablets
- 66-79 kg: 5 tablets
- ≥80 kg: 200 mcg/kg
For Onchocerciasis
- Dose: Single oral dose of 150 mcg/kg body weight 1
- Administration: Take on an empty stomach with water 1
- Retreatment intervals: 1
- Mass distribution campaigns: 12-month intervals most common
- Individual patients: May consider retreatment as short as 3-month intervals
Weight-based dosing table: 1
- 15-25 kg: 1 tablet (3 mg)
- 26-44 kg: 2 tablets
- 45-64 kg: 3 tablets
- 65-84 kg: 4 tablets
- ≥85 kg: 150 mcg/kg
Off-Label Uses (With Evidence)
Cutaneous Larva Migrans
- Dose: 200 mcg/kg single dose OR albendazole 400 mg daily for 3 days 2
- Clinical presentation: Self-limiting itchy serpiginous rash migrating 1-2 cm per day 2
Onchocerciasis (Extended Regimen for Symptomatic Cases)
- Specialist consultation required 2
- Exclude loiasis before treatment (critical safety consideration) 2
- Regimen: 2
- Doxycycline 200 mg daily for 6 weeks (targets Wolbachia)
- Ivermectin 200 mcg/kg monthly for 3 months starting day 1 of doxycycline
- Repeat ivermectin every 3-6 months until asymptomatic, then annually if needed
Other Parasitic Infections
- Ivermectin is used off-label for lymphatic filariasis, scabies, pediculosis, gnathostomiasis, and crusted scabies 2, 3, 4
Critical Safety Considerations
Loiasis Co-infection
- Absolute requirement: Exclude loiasis before treating onchocerciasis 2
- Risk: High microfilarial load death can cause severe encephalopathy in loiasis or onchocerciasis patients 3
Formulation Differences
- Oral solution provides significantly higher systemic exposure (AUC: 1653 ng·h/mL) compared to tablets (1056 ng·h/mL) or capsules (996 ng·h/mL) 5
- This may be relevant for systemic parasitic infections requiring higher drug levels 5
What Ivermectin Should NOT Be Used For
COVID-19
- Strong recommendation AGAINST use in ambulatory patients (moderate certainty of evidence) 2
- Conditional recommendation AGAINST use in hospitalized patients (very low certainty of evidence) 2
- Rationale: In vitro activity requires concentrations considerably higher than achievable in human plasma and lung tissue; clinical trials showed no mortality benefit, no effect on mechanical ventilation need, symptom resolution, or viral clearance 2, 6
Cancer
- No proven therapeutic utility 7
- Safety concern: Higher doses potentially needed for anticancer effects may cause significant adverse effects 7
Common Pitfalls to Avoid
- Do not use ivermectin for COVID-19 despite its accessibility and low cost—evidence clearly demonstrates lack of benefit 2, 6
- Always screen for loiasis before treating onchocerciasis to prevent fatal encephalopathy 2, 3
- Remember ivermectin does not kill adult O. volvulus worms—only microfilariae are affected 1
- Administer on empty stomach to optimize absorption 1
- Verify eradication with follow-up testing in strongyloidiasis 1