[6] 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.

[18] 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.

"[30] 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.

[39] Any benefit of treatment must be balanced against side effects, which include psychiatric symptoms and increased rates of vomiting.

There was also evidence that suggested that oseltamivir prevented some people from producing sufficient numbers of their own antibodies to fight infection.

The authors recommended that guidance should be revised to take account of the evidence of small benefit and increased risk of harms.

[6][7][9][28][29][31] As of 2017[update], the CDC does not recommend to use oseltamivir generally for prevention due to concerns that widespread use will encourage resistance development.

[27] As of 2011[update], reviews concluded that when oseltamivir is used preventatively it decreases the risk of exposed people developing symptomatic disease.

[citation needed] Oseltamivir's effect on the heart is unclear: it may reduce cardiac symptoms, but may also induce serious arrhythmias.

[43][44] Neuropsychiatric symptoms and body pain, followed by skin problems, were identified as the side effects most significantly reducing patient satisfaction on a drug review platform.

[46] It is pregnancy category B in Australia, meaning that it has been taken by a small number of women without signs of problems and in animal studies it looks safe.

[25] The vast majority of mutations conferring resistance are single amino acid residue substitutions (His274Tyr in N1) in the neuraminidase enzyme.

[50] In severely immunocompromised patients there were reports of prolonged shedding of oseltamivir- (or zanamivir)-resistant virus, even after oseltamivir treatment was stopped.

[6] As of December 15, 2010[update], the World Health Organization (WHO) reported 314 samples of the prevalent 2009 pandemic H1N1 flu tested worldwide showed resistance to oseltamivir.

[52] During 2011, a new influenza A(H1N1)2009 variant with mildly reduced oseltamivir (and zanamivir) sensitivity was detected in more than 10% of community specimens in Singapore and more than 30% of samples from northern Australia.

[57] In January 2012, the US and European CDCs reported all seasonal flu samples tested since October 2011 to be oseltamivir susceptible.

[50] In the study with the 18% resistance rate, the subjects were children, many of whom had not been previously exposed to influenza virus and therefore had a weakened immune response; the results suggest that higher and earlier dosing may be necessary in such populations.

[68] In 1999, the FDA approved oseltamivir phosphate for the treatment of influenza in adults[69] based on two double-blind, randomized, placebo-controlled clinical trials.

[70] In June 2002, the European Medicines Agency (EMA) approved oseltamivir phosphate for prophylaxis and treatment of influenza.

In 2003, a pooled analysis of ten randomised clinical trials concluded that oseltamivir reduced the risk of lower respiratory tract infections resulting in antibiotic use and hospital admissions in adults.

Defense Secretary Donald Rumsfeld, who was a past chairman of Gilead Sciences, recused himself from all government decisions regarding the drug.

[73] In 2006, a Cochrane Review (since withdrawn) raised controversy by concluding that oseltamivir should not be used during routine seasonal influenza because of its low effectiveness.

[74] In December 2008, the Indian drug company Cipla won a case in India's court system allowing it to manufacture a cheaper generic version of Tamiflu, called Antiflu.

[76] The National Institute for Health and Care Excellence (NICE), the CDC, the WHO, and the ECDC maintained their recommendation to use oseltamivir.

[78] In 2011, a freedom of information request to the European Medicines Agency (EMA) provided Cochrane with reports from 16 Roche oseltamivir trials.

[79] In 2014, Cochrane published an updated review based solely on full clinical study reports and regulatory documents.

[80] The drug may limit the ability of the virus to invade the crypt cells of the small intestine and decrease gastrointestinal bacterial colonization and toxin production.