Ivermectin Dosing for Parasitic Infections
The recommended dosing regimen for ivermectin is 200 mcg/kg orally as a single dose for strongyloidiasis, and 150 mcg/kg orally as a single dose for onchocerciasis, with specific repeat dosing schedules based on the parasitic infection being treated. 1
Standard Dosing by Indication
Strongyloidiasis
- Dose: 200 mcg/kg orally as a single dose 1
- Administration: Take tablets on an empty stomach with water
- Follow-up: Stool examinations should be performed to verify eradication
- Alternative regimen: For chronic uncomplicated strongyloidiasis, 200 mcg/kg for 2 consecutive days has shown 100% cure rate with minimal side effects 2
Onchocerciasis
- Dose: 150 mcg/kg orally as a single dose 1
- Administration: Take tablets on an empty stomach with water
- Retreatment intervals:
- Additional therapy: For onchocerciasis, doxycycline 200 mg daily for 6 weeks is recommended to target symbiotic Wolbachia bacteria 3
Scabies
- Standard scabies: 200 mcg/kg orally as a single dose, repeated in 2 weeks 3
- Crusted scabies: Combination treatment with topical scabicide (5% permethrin cream applied daily for 7 days then twice weekly) plus oral ivermectin 200 mcg/kg on days 1,2,8,9, and 15 3
Cutaneous Larva Migrans
Weight-Based Dosing Table for Strongyloidiasis (3 mg tablets)
| Body Weight (kg) | Number of 3-mg Tablets |
|---|---|
| 15-24 | 1 tablet |
| 25-35 | 2 tablets |
| 36-50 | 3 tablets |
| 51-65 | 4 tablets |
| 66-79 | 5 tablets |
| ≥80 | Calculate 200 mcg/kg |
Weight-Based Dosing Table for Onchocerciasis (3 mg tablets)
| Body Weight (kg) | Number of 3-mg Tablets |
|---|---|
| 15-25 | 1 tablet |
| 26-44 | 2 tablets |
| 45-64 | 3 tablets |
| 65-84 | 4 tablets |
| ≥85 | Calculate 150 mcg/kg |
Special Considerations
Administration Recommendations
- Take on an empty stomach with water to increase bioavailability 3
- For scabies treatment, ivermectin should be taken with food to increase bioavailability and penetration into the epidermis 3
Renal Impairment
- No dosage adjustments required in patients with renal impairment 3
Hepatic Impairment
- Safety of multiple doses in patients with severe liver disease is not known 3
Pregnancy
- Classified as "human data suggest low risk" in pregnancy and probably compatible with breastfeeding 3
- Permethrin or pyrethrins with piperonyl butoxide may be preferred first-line treatments during pregnancy 3
Clinical Pearls and Pitfalls
Efficacy Considerations
- Ivermectin has limited ovicidal activity for scabies, necessitating a second dose after 2 weeks 3
- For strongyloidiasis, persistent eosinophilia after treatment is associated with a high treatment failure rate (77%) 2
- For scabies, a single dose of ivermectin has shown efficacy in otherwise healthy patients and many HIV-infected patients 4
Safety Considerations
- Generally well-tolerated with fewer side effects compared to alternatives like thiabendazole 2
- One study showed increased mortality among elderly, debilitated persons, but this has not been confirmed in subsequent reports 3
- Avoid in children weighing <15 kg due to limited safety data 1
COVID-19 Warning
- Despite in vitro activity against SARS-CoV-2, ivermectin is not recommended for treatment of COVID-19 in either hospitalized or ambulatory patients 3
By following these evidence-based dosing guidelines and considering the specific parasitic infection being treated, clinicians can optimize the therapeutic efficacy of ivermectin while minimizing potential adverse effects.