Does Oseltamivir (Tamiflu) help?

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Last updated: March 31, 2025View editorial policy

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From the Guidelines

Tamiflu (oseltamivir) can help reduce the duration and severity of flu symptoms when taken within 48 hours of symptom onset, as recommended by the most recent guidelines 1.

Key Points to Consider

  • For adults and children over 40kg, the typical dose is 75mg twice daily for 5 days.
  • For treatment of children, dosing is weight-based:
    • 30mg twice daily for those weighing less than 15kg
    • 45mg twice daily for 15-23kg
    • 60mg twice daily for 23-40kg
  • Tamiflu works by preventing the influenza virus from spreading inside your body, potentially shortening illness duration by 1-2 days and reducing complications.
  • Common side effects include nausea and vomiting, which can be minimized by taking with food.
  • Tamiflu is not effective against the common cold or other viral infections, only influenza viruses.
  • For maximum benefit, start treatment as soon as possible after symptoms begin, ideally within the first 24-48 hours.

Important Considerations

  • The American Academy of Pediatrics (AAP) and the Centers for Disease Control and Prevention (CDC) recommend oseltamivir as the preferred treatment for influenza in children 1.
  • Oseltamivir is available in capsule and oral suspension formulations, and the dose should be adjusted based on renal insufficiency.
  • The CDC recommends routine chemoprophylaxis with oseltamivir or zanamivir for 7 days after last known exposure, with a minimum of 14 days and continuing for 7 days after last known exposure if part of an institutional outbreak 1.

From the FDA Drug Label

The FDA drug label does not answer the question.

From the Research

Efficacy of Tamiflu

  • Tamiflu (oseltamivir) has been shown to reduce the duration of symptomatic illness and hasten the return to normal levels of activity when initiated promptly in patients with naturally acquired influenza 2.
  • Studies have demonstrated that oseltamivir reduces the duration of the disease by up to 1.5 days and the severity of illness by up to 38% compared with placebo when initiated within 36 hours of symptom onset 2.
  • Oseltamivir has also been shown to be effective in preventing the development of naturally acquired influenza by >70% compared with placebo in unvaccinated otherwise healthy adults 2.

Clinical Benefits

  • Oseltamivir has been found to reduce the time to alleviation of illness by 19% compared with placebo, and recipients returned to normal health status, regained ability to perform usual activities, and regained normal sleep patterns significantly faster than placebo recipients 3.
  • The median duration of troublesome influenza symptoms, such as fatigue and myalgia, was significantly reduced by oseltamivir treatment 3.
  • Oseltamivir was well tolerated, with transient gastrointestinal effects being the most commonly reported events 2, 3.

Use in Specific Populations

  • Oseltamivir has been shown to be effective in the treatment of children with influenza, and data suggest that the drug may also be of use in high-risk populations such as the elderly or those with chronic cardiac or respiratory disease 2.
  • Oseltamivir may increase survival when used within five days of symptom onset in influenza H1N1-infected patients who require ICU admission 4.
  • The clinical effectiveness of oseltamivir for children with influenza A and B has been investigated, and results suggest that the duration of fever after administration of the first dose of oseltamivir was shorter in older patients and in patients with influenza A infection than in patients with influenza B infection 5.

References

Guideline

Guideline Directed Topic Overview

Dr.Oracle Medical Advisory Board & Editors, 2025

Research

Influenza treatment with oseltamivir outside of labeled recommendations.

American journal of health-system pharmacy : AJHP : official journal of the American Society of Health-System Pharmacists, 2015

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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