Oseltamivir, sold under the brand name Tamiflu among others, is an antiviral medication used to treat and prevent influenza A and influenza B, viruses that cause the flu. Many medical organizations recommend it in people who have complications or are at high risk of complications within 48 hours of first symptoms of infection. They recommend it to prevent infection in those at high risk, but not the general population. The Centers for Disease Control and Prevention (CDC) recommends that clinicians use their discretion to treat those at lower risk who present within 48 hours of first symptoms of infection. It is taken by mouth, either as a pill or liquid. Recommendations regarding oseltamivir are controversial as are criticisms of the recommendations. A 2014 Cochrane Review concluded that oseltamivir does not reduce hospitalizations, and that there is no evidence of reduction in complications of influenza. Two meta-analyses have concluded that benefits in those who are otherwise healthy do not outweigh its risks. They also found little evidence regarding whether treatment changes the risk of hospitalization or death in high risk populations. However, another meta-analysis found that oseltamivir was effective for prevention of influenza at the individual and household levels. Common side effects include vomiting, diarrhea, headache, and trouble sleeping. Other side effects may include psychiatric symptoms and seizures. In the United States, it is recommended for influenza infections during pregnancy. It has been taken by a small number of pregnant women without signs of problems. Dose adjustment may be needed in those with kidney problems. Oseltamivir was approved for medical use in the US in 1999. It was the first neuraminidase inhibitor available by mouth. It is on the World Health Organization's List of Essential Medicines but was downgraded to "complementary" status in 2017. A generic version was approved in the US in 2016. In 2023, it was the 250th most commonly prescribed medication in the United States, with more than 1 million prescriptions.
Medical uses
Oseltamivir is used for the prevention and treatment of influenza caused by influenza A and B viruses. It is on the World Health Organization's List of Essential Medicines. The World Health Organization (WHO) supports its use for severe illness due to confirmed or suspected influenza virus infection in critically ill people who have been hospitalized. Oseltamivir's risk-benefit ratio is controversial. In 2017, it was moved from the core to the complementary list based on its lower cost-effectiveness. The Expert Committee did not recommend the deletion of oseltamivir from the EML and EMLc, recognizing that it is the only medicine included on the Model Lists for critically ill patients with influenza and for influenza pandemic preparedness. However, the Committee noted that, since the inclusion of oseltamivir on the Model List in 2009, new evidence in seasonal and pandemic influenza has lowered earlier estimates of the magnitude of effect of oseltamivir on relevant clinical outcomes. The Committee recommended that the listing of oseltamivir be amended, moving the medicine from the core to the Complementary List, and that its use be restricted to severe illness due to confirmed or suspected influenza virus infection in critically ill hospitalized patients. The Expert Committee noted that WHO guidelines for pharmacological management of pandemic and seasonal influenza would be updated in 2017: unless new information is provided to support the use of oseltamivir in seasonal and pandemic outbreaks, the next Expert Committee might consider oseltamivir for deletion.
High-risk people The US Centers for Disease Control and Prevention (CDC), European Centre for Disease Prevention and Control (ECDC), Public Health England, and the American Academy of Pediatrics (AAP) recommend the use of oseltamivir for people who have complications or are at high risk for complications. This includes those who are hospitalized, young children, those over the age of 65, people with other significant health problems, those who are pregnant, and Indigenous peoples of the Americas among others. The Infectious Disease Society of America takes the same position as the CDC. A systematic review of systematic reviews did not find evidence for benefits in people who are at risk, noting that "the trials were not designed or powered to give results regarding serious complications, hospitalization and mortality", as did a 2014 Cochrane Review. The Cochrane Review further recommended: "On the basis of the findings of this review, clinicians and healthcare policy-makers should urgently revise current recommendations for use of the neuraminidase inhibitors (NIs) for individuals with influenza." That is not utilizing NIs for prevention or treatment "Based on these findings there appears to be no evidence for patients, clinicians or policy-makers to use these drugs to prevent serious outcomes, both in annual influenza and pandemic influenza outbreaks." The CDC, ECDC, Public Health England, Infectious Disease Society of America, the AAP, and Roche (the originator) reject the conclusions of the Cochrane Review, arguing in part that the analysis inappropriately forms conclusions about outcomes in people who are seriously ill based on results obtained primarily in healthy populations, and that the analysis inappropriately included results from people not infected with influenza. The EMA did not change its labeling of the drug in response to the Cochrane study. A 2014 review recommended that all people admitted to intensive care units during influenza outbreaks with a diagnosis of community-acquired pneumonia receive oseltamivir until the absence of influenza infection is established by polymerase chain reaction (PCR) testing. A 2015 systematic review and meta-analysis found oseltamivir effective at treating the symptoms of influenza, reducing the length of hospitalization, and reducing the risk of otitis media. The same review found that oseltamivir did not significantly increase the risk of adverse events. A 2016 systematic review found that oseltamivir slightly reduced the time it takes for the symptoms of influenza to be alleviated, and that it also increased the risk of "nausea, vomiting, [and] psychiatric events in adults and vomiting in children." The decrease in duration of sickness was about 18 hours.
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