From the Guidelines
Tamiflu (oseltamivir) is recommended for treating influenza within 48 hours of symptom onset, with a standard adult dosage of 75 mg twice daily for 5 days, and weight-based dosing for children. The treatment works best when started early, ideally within 24-48 hours of symptoms appearing, as it reduces symptom duration by about 1-2 days and may decrease complications, especially in high-risk patients 1.
Key Considerations
- The dosage for children is based on their weight, with the following recommendations:
- Less than 15 kg: 30 mg twice daily
- 15-23 kg: 45 mg twice daily
- 23-40 kg: 60 mg twice daily
- More than 40 kg: 75 mg twice daily
- For infants, the dosage is as follows:
- Term infants 0-8 months: 3 mg/kg per dose twice daily
- Term infants 9-11 months: 3.5 mg/kg per dose twice daily
- Preterm infants require a lower dose, based on their postmenstrual age, and should be consulted with a pediatric infectious disease physician for guidance 1.
Administration and Side Effects
- Oseltamivir can be administered orally without regard to meals, although taking it with food may improve gastrointestinal tolerability 1.
- Common side effects include nausea, vomiting, and headache, which can be minimized by taking the medication with food.
- Vomiting is the only oseltamivir-attributable adverse effect that was greater in children, occurring in approximately 5% of treated patients 1.
Importance of Early Treatment
- Early treatment provides the best outcomes, and antiviral treatment should be started as soon as possible after illness onset, without waiting for a definitive influenza test result 1.
- Treatment after 48 hours of symptoms in adults and children with moderate to severe disease or with progressive disease has been shown to provide some benefit and should be strongly considered 1.
From the FDA Drug Label
Oseltamivir phosphate for oral suspension is indicated for the treatment of acute, uncomplicated illness due to influenza A and B infection in patients 2 weeks of age and older who have been symptomatic for no more than 48 hours. In both trials, there was a 1.3-day reduction in the median time to improvement in influenza-infected subjects who received oseltamivir phosphate 75 mg twice a day for 5 days compared to subjects who received placebo. The treatment of influenza with oseltamivir is indicated for patients 2 weeks of age and older who have been symptomatic for no more than 48 hours.
- The dosage is 75 mg twice a day for 5 days for adults and adolescents.
- The effectiveness of oseltamivir in treating influenza has been demonstrated in clinical trials, with a reduction in the median time to improvement of 1.3 days compared to placebo 2.
- Important considerations include the fact that oseltamivir is not a substitute for early influenza vaccination and that prescribers should consider available information on influenza drug susceptibility patterns and treatment effects when deciding whether to use oseltamivir 2.
From the Research
Tamiflu Treatment Overview
- Tamiflu, also known as oseltamivir, is a neuraminidase inhibitor used to treat influenza A and B 3, 4, 5, 6, 7
- The efficacy of Tamiflu in treating influenza has been studied in various populations, including healthy adults and children, as well as critically ill patients 3, 4, 5, 7
Efficacy of Tamiflu
- A systematic review and network meta-analysis found that oseltamivir was associated with a shorter time to alleviation of influenza symptoms compared to placebo, but not as effective as zanamivir in shortening the time to alleviation of symptoms 3
- Another study found that oseltamivir was effective in reducing the duration of fever in children with influenza A and B, but the effectiveness varied depending on the age of the patient and the type of influenza virus 4
- In critically ill patients, the evidence for the efficacy of oseltamivir is limited, and further research is needed to determine its effectiveness in this population 5, 7
Safety of Tamiflu
- Oseltamivir has been associated with adverse events such as nausea and vomiting, particularly at higher doses 3
- A study found that baloxavir, another antiviral medication, was associated with a lower risk of total adverse events compared to oseltamivir 3
- The safety profile of oseltamivir in critically ill patients is not well established, and further research is needed to determine its safety in this population 5, 7
Alternative Treatment Options
- Other neuraminidase inhibitors, such as zanamivir and peramivir, may be effective alternatives to oseltamivir in certain situations, such as when resistance to oseltamivir is present 5, 7
- Intravenous zanamivir has been found to be a viable option for critically ill patients with influenza, particularly when oral antiviral therapy is not preferred or when oseltamivir resistance is increased 7