What is the maximum daily dose of ivermectin for an average adult?

Maximum Daily Dose of Ivermectin

For standard parasitic infections in adults, the maximum daily dose of ivermectin is 200 mcg/kg as a single dose, though higher doses up to 600 mcg/kg/day for 3 consecutive days have been studied and found safe in clinical trials. 1, 2, 3

Standard Maximum Dosing by Clinical Context

FDA-Approved Maximum Dose

• The FDA label documents that ivermectin has been studied at doses ranging from 30 to 120 mg (333 to 2000 mcg/kg) in healthy volunteers, demonstrating dose-proportional pharmacokinetics and tolerability. 2
• The standard therapeutic dose remains 200 mcg/kg as a single oral dose for most approved indications. 1, 4

Guideline-Recommended Maximum Doses by Indication

Single-Dose Regimens:

• For strongyloidiasis, cutaneous larva migrans, and most parasitic infections: 200 mcg/kg as a single dose 5, 1, 4
• For pediculosis pubis: 250 mcg/kg, repeated in 2 weeks 1
• For head lice (off-label): 400 mcg/kg on days 1 and 8 1

Multi-Day Regimens (Higher Total Exposure):

• For Loeffler's syndrome: 200 mcg/kg once daily for 3 consecutive days 1
• For immunocompromised patients with strongyloidiasis: 200 mcg/kg on days 1,2,15, and 16 1, 4
• For onchocerciasis: 200 mcg/kg monthly for 3 months (combined with doxycycline) 5, 4
• For crusted (Norwegian) scabies: 200 mcg/kg on days 1,2,8,9, and 15 (requires specialist consultation) 1

Research-Supported Higher Doses

Clinical Trial Evidence:

• Doses up to 600 mcg/kg/day for 3 consecutive days have been studied in malaria transmission reduction trials and found to be safe and well-tolerated. 3
• Single doses up to 800 mcg/kg have been used for onchocerciasis treatment. 3
• The FDA label confirms that doses up to 2000 mcg/kg have been administered in pharmacokinetic studies without significant safety concerns. 2

Critical Safety Considerations

Absolute Contraindications to Higher Doses

• Children under 10 years or weighing <15 kg: Ivermectin may cross the blood-brain barrier and cause neurotoxicity in young children; permethrin is recommended instead. 1, 4
• Loiasis co-infection: Always exclude Loa loa infection before treating with ivermectin in anyone who has traveled to endemic regions, as hypermicrofilaremic patients (>8,000 mf/mL) risk severe adverse events including encephalitis. 1, 4

Special Population Warnings

• Elderly and debilitated patients: One study demonstrated increased mortality in this population, though not confirmed in subsequent reports; use with caution. 4
• Severe hepatic impairment: Use with extreme caution, as safety of multiple doses is not established. 1
• Renal impairment: No dose adjustments required. 1, 4

Common Pitfalls to Avoid

• Forgetting repeat doses: For scabies, the 2-week repeat dose at 200 mcg/kg is mandatory due to limited ovicidal activity. 1
• Incorrect food timing: Standard dosing should be taken on an empty stomach with water for optimal bioavailability, though scabies treatment specifically requires administration with food to enhance epidermal penetration. 1, 4
• Inadequate screening: Always exclude loiasis before treating lymphatic filariasis or onchocerciasis, and exclude onchocerciasis before treating loiasis. 4
• Premature concern about treatment failure: Itching may persist for up to 2 weeks after successful treatment due to allergic dermatitis, not treatment failure. 1, 6