Researchers said that when treating childhood fever, parents should be warned to use drugs only in minimum dose necessary or as directed by a physician.
Combination or alternative use of anti-fever drugs frequently for treating fever in children may result in an unsafe state.
Fever is common in children and can often cause distress, parental anxiety, and - in some parents - 'fever phobia' (undue fear and overly aggressive treatment of fever).
But should these drugs be used together, or alternately, for which children, and at what dose and frequency? Advice is inconsistent, leading to confusion and frustration among parents, nurses, and doctors.
To try to answer these questions, researchers in Bristol searched the scientific literature, but found very little evidence to support prescribing paracetamol and ibuprofen in combination or alternately.
They also found other important gaps in the evidence, including limited safety data and no clear definition of what is a clinically important temperature difference after treatment.
Until such evidence is available, the role of combined anti-fever drugs is uncertain, they warn.
Given that the absence of evidence from trials is at odds with strongly held parental beliefs in many cases, and given the desire among parents and clinicians to do something when faced with febrile children, it seems churlish to conclude that combined treatment should be withheld from all children, say the authors.
But parents should be advised to use the minimum treatment necessary, they conclude.