A systematic review and meta-analysis of the use of antipyretic drugs during influenza on mortality. Randomized and placebo-controlled studies in humans have not been conducted, eight animal studies (mice and chickens) have been found.
Antipyretics (aspirin, paracetamol, diclofenac) taken during flu increased mortality by 34%.
Paracetamol and Ibuprofen are recommended for adults and children as antipyretics during flu, despite the absence of scientific evidence of their effectiveness and safety. Furthermore, there is evidence showing that fever occurring during a disease increases survival chances and that using antipyretics may result in an unfavorable outcome. In non-human mammals, antipyretic treatment increases the risk of mortality due to different bacterial, viral and parasitic infections. There is also evidence from animal models that antipyretics may impair the response in bacterial pneumonia which may complicate influenza illness.
Similar to influenza virus, many strains of pneumococcus are temperature-sensitive and die when the temperature is between 40–41°C. In mice, treatment with aspirin to treat pneumococcal infection increased mortality rates two to three-fold.