What is the recommended dose of lysine (L-lysine) to prevent influenza (flu)?

Lysine is NOT Recommended for Influenza Prevention

Lysine supplementation has no established role in preventing influenza, and current evidence-based guidelines exclusively recommend vaccination and antiviral medications (oseltamivir, zanamivir, baloxavir) for influenza prevention. There is no guideline-supported dosing regimen for lysine in flu prevention because it is not a recognized preventive intervention.

Why Lysine is Not Recommended

Lack of Evidence for Influenza

• No major influenza prevention guidelines from the Advisory Committee on Immunization Practices (ACIP), American Academy of Pediatrics, or Infectious Diseases Society of America mention lysine as a preventive or therapeutic agent for influenza 1.
• While one in vitro study suggested lysine may block influenza A virus infection in cell culture 2, this has never been validated in human clinical trials or translated into clinical recommendations.
• The mechanism proposed (arginine antagonism) has not been demonstrated to be clinically relevant for influenza prevention in humans 2, 3.

Evidence Against Lysine for Viral Infections

• A systematic review of lysine for herpesvirus (a different viral family) found no antiviral properties and recommended immediate cessation of lysine supplementation due to complete lack of efficacy 4.
• Lysine does not antagonize arginine effectively in all species, and lowering arginine levels could be harmful since it is an essential amino acid 4.
• The theoretical basis for lysine's antiviral activity remains unproven in clinical settings 5, 3.

Evidence-Based Influenza Prevention

Vaccination (Primary Prevention)

• Annual influenza vaccination is the cornerstone of prevention, with inactivated influenza vaccines (IIV) and live attenuated influenza vaccines (LAIV) recommended for all persons ≥6 months of age 1.
• Standard-dose vaccines contain 15 μg of hemagglutinin per vaccine virus in a 0.5-mL dose 1.
• High-dose (60 μg per virus) and adjuvanted vaccines are available for adults ≥65 years 1.

Antiviral Chemoprophylaxis (When Indicated)

• Oseltamivir is FDA-approved for prophylaxis and recommended at 75 mg once daily for adults, with weight-based dosing for children 1.
• Zanamivir 10 mg (two 5-mg inhalations) once daily is approved for prophylaxis in persons ≥5 years 1.
• Baloxavir is approved for treatment but not prophylaxis 1.
• Chemoprophylaxis duration is typically 7-10 days for outbreak control or throughout the influenza season for high-risk individuals 1.

Common Pitfalls to Avoid

• Do not recommend lysine for influenza prevention as it lacks any evidence base and may give patients false reassurance, delaying proven interventions 1.
• Do not confuse lysine's theoretical role in herpesvirus (which itself is unproven) with influenza, as these are entirely different viral families with different replication mechanisms 4, 2.
• Prioritize vaccination over all other interventions as it is the only intervention proven to reduce influenza-related morbidity and mortality 1.
• Reserve antiviral chemoprophylaxis for specific high-risk situations (institutional outbreaks, immunocompromised patients, vaccine contraindications) rather than routine use 1.