Fever is a frequent response to infection. The inflammatory response to invading organisms often leads to a febrile reaction, which many have suggested is an adaptive response, that might actually have an evolutionary advantage, and improve survival from serious infections. Of course it is also possible that it is an epiphenomenon, without survival impacts, or that it had a minor effect in the past, but not compared to ICU and antibiotics.
In countries with high resources, death from sepsis is rare, outside of intensive care units. So this study (Young P, et al. Acetaminophen for Fever in Critically Ill Patients with Suspected Infection. The New England journal of medicine. 2015.) recruited the kind of patients where an effect of fever, and any potential adverse effect of using antipyretics, would be evident.
Basically they found nothing.
There was no adverse or beneficial effect of treating fever with acetaminophen (paracetamol for the europeans) on any of the outcomes in this large multi-center trial of 700 critically ill adults in Australian and new Zealand ICUs. Either the primary outcome “ICU-free days” or the secondary outcomes.
Like anything else it might be different in children or newborns, but there wasn’t even the hint of an effect. Which means, I think that we don’t need to worry too much about giving acetaminophen to febrile babies or our own children. If it makes them feel better, then go ahead.