What is the recommended dose of ivermectin for treating parasitic infections?

Recommended Dosage of Ivermectin for Parasitic Infections

The recommended dosage of ivermectin for treating parasitic infections is 200 μg/kg as a single oral dose for most parasitic infections, with specific dosing adjustments based on the type of infection.

Standard Dosing Guidelines

Strongyloidiasis

• Dosage: 200 μg/kg as a single oral dose 1
• Take tablets on an empty stomach with water
• Follow-up stool examinations should be performed to verify eradication 1
• Dosing based on weight:
  • 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: Calculate at 200 μg/kg 1

Onchocerciasis

• Dosage: 150 μg/kg as a single oral dose 1
• Take tablets on an empty stomach with water
• Retreatment may be considered at intervals as short as 3 months for individual patients
• In mass distribution campaigns, the most common dose interval is 12 months 1
• Alternative regimen for severe cases: Doxycycline 200 mg once daily for 6 weeks plus ivermectin 200 μg/kg monthly for 3 months 2

Cutaneous Larva Migrans

• Dosage: 200 μg/kg as a single oral dose 2
• Alternative: Albendazole 400 mg once daily for 3 days

Special Parasitic Infections

Pediculosis Pubis (Pubic Lice)

• Dosage: 250 μg/kg repeated in 2 weeks 2
• Take with food to increase bioavailability and penetration into the epidermis
• No dosage adjustment required for renal impairment
• Safety of multiple doses in severe liver disease is not established 2

Scabies

• Dosage: 200 μg/kg as a single oral dose, repeated after 14 days 3, 4
• Ivermectin has limited ovicidal activity, necessitating the second dose 3
• Take with food to increase bioavailability 3

Important Considerations

Efficacy by Parasite Type

• Highly effective (>80% cure rate) for:
  • Strongyloidiasis (83% cure rate) 5
  • Ascaris lumbricoides 5
  • Scabies (91-100% cure rate) 4
• Less effective for:
  • Trichuris trichiura (11% cure rate) 5
  • Hookworm infections (ineffective) 5

Safety Considerations

• Generally well-tolerated with minimal side effects
• Avoid in children under 15 kg (though emerging evidence supports safety) 3
• Do not apply to eyes; use ophthalmic ointment for eyelash infestations 2
• Exclude Loa loa infection before treatment in patients who have traveled to endemic regions 3
• Side effects correlate with pretreatment microfilarial counts in onchocerciasis 6

Follow-up Recommendations

• Evaluate after 1-2 weeks if symptoms persist
• Repeat treatment may be necessary if parasites are still detected
• For scabies, pruritus may persist for several weeks despite successful treatment 3

Treatment Algorithm

1. Identify specific parasitic infection through appropriate diagnostic tests
2. Select appropriate dose based on infection type:
   • Most infections: 200 μg/kg single dose
   • Onchocerciasis: 150 μg/kg single dose
   • Pediculosis pubis: 250 μg/kg repeated in 2 weeks
3. Calculate dose based on patient weight using FDA-approved weight bands
4. Administer with appropriate instructions (with/without food)
5. Schedule follow-up to confirm eradication
6. Consider repeat dosing for infections with limited ovicidal activity

Ivermectin remains one of the most effective antiparasitic medications available, with specific dosing regimens established for different parasitic infections to maximize efficacy while minimizing adverse effects.