What is the recommended dose of aspirin (acetylsalicylic acid) for Kawasaki disease?

Aspirin Dosing in Kawasaki Disease

The recommended aspirin dose for Kawasaki disease is 80-100 mg/kg/day divided into 4 doses during the acute phase, continued until the patient is afebrile for 48-72 hours, then reduced to 3-5 mg/kg/day as a single daily dose. 1, 2

Acute Phase Dosing (High-Dose)

• Administer 80-100 mg/kg/day divided into 4 doses during the acute inflammatory phase, given concurrently with IVIG (2 g/kg as a single infusion). 1, 2

• Continue this high-dose regimen until the patient has been afebrile for 48-72 hours. 1, 2

• Some institutions continue high-dose aspirin until day 14 of illness AND 48-72 hours after fever cessation, though practices vary. 1

• The primary purpose of high-dose aspirin is anti-inflammatory and antipyretic effects, not prevention of coronary abnormalities (aspirin does not reduce coronary artery aneurysm formation). 1, 3

Transition to Low-Dose (Antiplatelet Phase)

• Reduce to 3-5 mg/kg/day as a single daily dose once fever resolves and high-dose therapy is discontinued. 1, 2

• Continue low-dose aspirin until 6-8 weeks after disease onset if no coronary abnormalities are detected on echocardiography. 1, 2

• For patients who develop coronary abnormalities, continue low-dose aspirin indefinitely for its antiplatelet effects. 1, 2

Important Clinical Considerations

Drug Interactions

• Avoid ibuprofen in patients taking aspirin for antiplatelet effects, as ibuprofen antagonizes aspirin-induced irreversible platelet inhibition. 1

Reye Syndrome Risk

• Reye syndrome is a risk in children taking salicylates during active varicella or influenza infection. 1

• Discontinue aspirin during influenza or chickenpox infections and substitute with clopidogrel or low-molecular-weight heparin to maintain antithrombotic coverage. 1

• Administer annual influenza vaccine to all children on long-term aspirin therapy. 1, 2

Vaccination Timing

• Defer varicella vaccine for 6 weeks after aspirin administration per vaccine manufacturer recommendations. 1

Evidence Regarding Aspirin Dose Controversy

While the American Heart Association recommends 80-100 mg/kg/day, emerging evidence suggests lower doses may be equally effective:

• A 2020 retrospective study of 2,369 patients found that 20-29 mg/kg/day did not increase the risk of coronary artery aneurysms compared to 30-50 mg/kg/day, and may have lower risk for liver function effects. 4

• A 2021 randomized trial demonstrated that eliminating high-dose aspirin entirely (using only IVIG) did not significantly increase coronary abnormalities. 5

However, current guideline recommendations from the American Heart Association remain 80-100 mg/kg/day and should be followed in clinical practice until guidelines are formally updated. 1, 2

Escalation for Coronary Involvement

For patients with documented coronary abnormalities:

• Small aneurysms: Continue low-dose aspirin indefinitely. 1, 2

• Moderate aneurysms (4-6 mm): Add a second antiplatelet agent such as clopidogrel. 3, 2

• Giant aneurysms (≥8 mm): Add anticoagulation with warfarin (target INR 2.0-3.0) or therapeutic low-molecular-weight heparin. 2, 6