What is the recommended dose of ivermectin (antiparasitic medication) in tablets for adults?

Ivermectin Tablet Dosing for Adults

The standard dose of ivermectin tablets for adults is 200 mcg/kg (0.2 mg/kg) as a single oral dose, taken on an empty stomach with water. 1, 2

Standard Dosing by Body Weight

For practical administration, the FDA-approved dosing guidelines provide the following tablet counts (using 3 mg tablets) 2:

• 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: Calculate 200 mcg/kg

Administration Guidelines

Ivermectin must be taken on an empty stomach with water to optimize bioavailability. 1, 2 Taking the medication with food increases absorption and enhances drug penetration into the epidermis, which is beneficial for ectoparasitic infections like scabies. 1

Indication-Specific Dosing Variations

Strongyloidiasis (Intestinal Threadworm)

• Standard regimen: 200 mcg/kg single dose 1, 2
• Immunocompromised patients: 200 mcg/kg on days 1,2,15, and 16 1
• Hyperinfection syndrome: Requires prolonged treatment with specialist consultation 1

Scabies

• Standard regimen: 200 mcg/kg orally, repeated in 2 weeks 1
• The second dose is necessary because ivermectin has limited ovicidal activity and may not prevent hatching of eggs present at initial treatment 1

Onchocerciasis (River Blindness)

• Lower dose: 150 mcg/kg as a single dose 2
• Retreatment intervals typically 12 months in mass campaigns, but can be as short as 3 months for individual patients 2

Loiasis (African Eye Worm)

• Alternative dosing: 150-200 mcg/kg 1, 3
• May be given as single dose or repeated at monthly, quarterly, or biannual intervals depending on microfilarial load 1
• Critical caveat: Microfilarial threshold of <8000 mf/ml is generally recommended before ivermectin use to avoid severe adverse reactions 1

Important Clinical Considerations

Renal and Hepatic Impairment

No dose adjustments are required for renal impairment. 1 However, the safety of multiple doses in patients with severe liver disease is not established. 1

Pregnancy and Lactation

Ivermectin is classified as "human data suggest low risk" in pregnancy and is probably compatible with breastfeeding. 1 Permethrin is preferred as first-line for scabies in pregnant women when topical therapy is appropriate. 1

Pediatric Restrictions

Children under 10 years of age should not receive ivermectin for scabies. 1 Permethrin cream is the preferred treatment in this age group. 1

Critical Safety Warning

One study demonstrated increased mortality among elderly, debilitated persons who received ivermectin, though this has not been confirmed in subsequent reports. 1 Exercise caution when treating frail elderly patients and consider alternative therapies when appropriate.

Co-infection Screening

Always exclude co-existing onchocerciasis before treating loiasis, and exclude loiasis before treating lymphatic filariasis or onchocerciasis. 1 Co-infection can lead to severe Mazzotti reactions including encephalitis in hypermicrofilaremic patients. 1

Alternative Dosing in Literature

Some guidelines accept 150 mcg/kg as an alternative dose, particularly for onchocerciasis. 1, 3 However, the 200 mcg/kg dose is more widely recommended across multiple parasitic indications and represents the most current guideline consensus. 1, 2