What is the recommended intravenous immunoglobulin (IVIG) regimen and adjunct therapy for Kawasaki disease?

IVIG for Kawasaki Disease

Administer IVIG 2 g/kg as a single infusion over 10–12 hours combined with high-dose aspirin 80–100 mg/kg/day divided into four doses, initiated as early as possible within the first 10 days of fever onset. 1

Initial Treatment Regimen

• IVIG 2 g/kg as a single infusion is the cornerstone of treatment, with the highest level of evidence (Grade 1A) supporting its use within 10 days of symptom onset. 1

• High-dose aspirin 80–100 mg/kg/day should be given in four divided doses during the acute phase, administered concurrently with IVIG. 1

• This combined regimen reduces coronary artery abnormality risk from 15–25% down to approximately 5% for any abnormality and 1% for giant aneurysms. 1

• The infusion rate should start at 0.01 mL/kg/min (0.5 mg/kg/min) and may be gradually increased to a maximum of 0.10 mL/kg/min (5 mg/kg/min) if well-tolerated during the first 30 minutes. 2

Evidence on Aspirin Necessity

While the 2017 American Heart Association guideline recommends combined IVIG plus aspirin 3, two recent high-quality studies challenge the necessity of aspirin:

• A 2025 randomized trial of 134 children demonstrated noninferiority of IVIG alone compared with IVIG plus aspirin, with CAL occurrence at 6 weeks of 1.5% (IVIG-only) versus 2.9% (IVIG plus aspirin), showing no statistically significant difference. 4

• A 2024 retrospective cohort of 735 patients found no increased complications when ASA was omitted during acute phase treatment. 5

Despite this emerging evidence, the current American Heart Association guideline recommendation remains IVIG plus aspirin, and this should guide practice until formal guideline revision. 3, 1

Aspirin Dosing Algorithm

• Continue high-dose aspirin until the patient has been afebrile for 48–72 hours. 1

• Then transition to low-dose aspirin 3–5 mg/kg/day as a single daily dose. 1

• Continue low-dose aspirin until 6–8 weeks after disease onset if no coronary abnormalities are present on serial echocardiography. 1

• For children who develop coronary abnormalities, aspirin may be continued indefinitely. 1

Management of IVIG-Resistant Disease

Definition

• IVIG resistance is defined as persistent or recrudescent fever lasting ≥36 hours after completion of the initial 2 g/kg IVIG infusion. 1, 6

• IVIG resistance occurs in 10–20% of patients. 1

• A new rash without accompanying fever does not meet criteria for IVIG resistance. 6

First-Line Rescue Therapy

• Administer a second dose of IVIG 2 g/kg as a single infusion for IVIG-resistant patients (Class IIa, Level B). 3, 1

Second-Line Options (After Two IVIG Doses)

• Methylprednisolone 20–30 mg/kg IV daily for 3 days, with or without a subsequent oral prednisone taper (Class IIb, Level B). 3, 1

• Infliximab 5 mg/kg IV over 2 hours as a single infusion (Class IIb, Level C). 3, 1

Third-Line Therapies (Highly Refractory Disease)

• Cyclosporine may be considered in patients refractory to second IVIG infusion, infliximab, or steroids (Class IIb, Level C). 3, 1

• Plasma exchange is reserved for exceptional cases when all reasonable medical therapies have failed. 3, 1

Long-Term Antiplatelet Management Based on Coronary Findings

• No coronary abnormalities: Discontinue low-dose aspirin at 6–8 weeks after disease onset if serial echocardiograms remain normal. 1

• Small coronary aneurysms: Continue low-dose aspirin 3–5 mg/kg/day indefinitely. 1

• Moderate aneurysms (4–6 mm): Low-dose aspirin 3–5 mg/kg/day plus clopidogrel 1 mg/kg/day (maximum 75 mg/day). 1

• Giant aneurysms (≥8 mm): Low-dose aspirin 3–5 mg/kg/day plus warfarin with target INR 2.0–3.0. 1

Monitoring and Follow-Up

• Perform echocardiography at diagnosis, 2 weeks, and 6–8 weeks after treatment initiation. 1

• Use C-reactive protein (CRP) rather than ESR to monitor inflammation after IVIG therapy, as IVIG artificially elevates ESR. 1

Critical Caveats and Common Pitfalls

• Infants <1 year are at highest risk for incomplete presentations and paradoxically have the highest rates of coronary aneurysms if untreated. 1

• Never use ibuprofen in children taking aspirin for antiplatelet effects, as it antagonizes the irreversible platelet inhibition induced by aspirin. 1

• Defer measles, mumps, rubella, and varicella immunizations for 11 months after high-dose IVIG administration due to interference with vaccine efficacy. 1

• Annual influenza vaccination is mandatory for children on long-term aspirin therapy due to Reye syndrome risk during influenza infection. 1

• If an IVIG infusion is interrupted, restart the full 2 g/kg dose rather than attempting to calculate a partial dose, as therapeutic effect requires achieving adequate peak serum IgG levels. 7

• Fever occurring during the IVIG infusion is an infusion reaction, not IVIG resistance—manage by slowing or stopping the infusion and providing symptomatic treatment with acetaminophen and antihistamines. 6

• Children presenting after day 10 of illness should still receive IVIG if they have ongoing systemic inflammation (CRP >3.0 mg/dL) together with either persistent fever or coronary artery aneurysms. 1