What is the recommended dose of ivermectin for adults and children over 15 kilograms (kg) with conditions such as onchocerciasis, strongyloidiasis, or scabies?

Ivermectin Dosing Recommendations

For adults and children over 15 kg, ivermectin dosing is 200 mcg/kg as a single oral dose for strongyloidiasis and scabies, 150 mcg/kg for onchocerciasis, and 400 mcg/kg repeated in 7 days for head lice, with all doses taken with food except for strongyloidiasis and onchocerciasis which require an empty stomach. 1, 2, 3

FDA-Approved Indications and Dosing

Strongyloidiasis

• Single oral dose of 200 mcg/kg taken on an empty stomach with water 3
• For a 56-kg patient, this equals four 3-mg tablets (12 mg total) 1
• Additional doses generally not necessary, but follow-up stool examinations required to verify eradication 3

Onchocerciasis

• Single oral dose of 150 mcg/kg taken on an empty stomach with water 3
• Retreatment intervals: 12 months for mass distribution campaigns, or as short as 3 months for individual patients 3
• This dose produces marked reduction in skin microfilaria counts and ocular involvement with minimal side effects 4, 5

Off-Label Uses (Supported by CDC and AAP Guidelines)

Scabies

• 200 mcg/kg orally, repeated in 14 days (mandatory second dose) 1
• Must be taken WITH food to increase bioavailability and enhance drug penetration into the epidermis 1
• The second dose is critical because ivermectin has limited ovicidal activity—it kills adult mites but not all eggs 1
• For crusted (Norwegian) scabies in immunocompromised patients: intensive regimen of 200 mcg/kg on days 1,2,8,9, and 15, plus daily topical permethrin, requires specialist consultation 1

Head Lice (Pediculosis Capitis)

• 400 mcg/kg orally on day 1 and day 8 2
• Taken with food 2
• Neither oral nor topical ivermectin is FDA-approved for head lice, but the American Academy of Pediatrics recommends this regimen for treatment failures with topical agents 6, 2
• The day 7-8 repeat dose is mandatory to kill newly hatched nymphs from eggs present at initial treatment 2

Other Parasitic Infections

• Cutaneous larva migrans: 200 mcg/kg as a single dose 1
• Pediculosis pubis (pubic lice): 250 mcg/kg, repeated in 2 weeks 1
• Loeffler's syndrome (empirical): 200 mcg/kg once daily for 3 days 1
• Loiasis: 150-200 mcg/kg, most often as single dose but up to 10 days daily in endemic settings 6

Critical Safety Considerations

Absolute Contraindications

• Children weighing <15 kg or <10 years old: ivermectin may cross the blood-brain barrier and cause neurotoxicity 6, 1, 2
• Use permethrin 5% cream instead for this population 1, 2

Special Populations

• Pregnancy and breastfeeding: CDC and AAP classify as "human data suggest low risk" and probably compatible with breastfeeding 1
• Renal impairment: no dose adjustment required 1
• Hepatic impairment: use with extreme caution in severe liver disease 1, 2
• Elderly debilitated patients: one study showed increased mortality, though not confirmed in subsequent reports; use with caution 1

Common Pitfalls to Avoid

Forgetting the Second Dose

• For scabies and head lice, the repeat dose is mandatory due to limited ovicidal activity 1, 2
• Scabies: repeat at 14 days 1
• Head lice: repeat at 7-8 days 2

Incorrect Food Timing

• Strongyloidiasis and onchocerciasis: take on empty stomach 3
• Scabies, head lice, and most other indications: take WITH food 1, 2

Inadequate Contact Treatment

• For scabies, all household and sexual contacts within the previous month must be treated simultaneously 1

Misinterpreting Persistent Symptoms

• Itching may persist for up to 2 weeks after successful scabies treatment due to allergic dermatitis—this is not treatment failure 1
• Topical corticosteroids and oral antihistamines may help relieve these symptoms 6

Using in High Microfilarial Loads

• For loiasis, maintain microfilarial threshold below 8000 mf/ml when using ivermectin to reduce risk of severe adverse events 6
• Above 8000 mf/ml, consider albendazole or apheresis instead 6