Prevalence of exceeding maximum daily dose of paracetamol, and seasonal variations in cold-flu season.

Aims: To estimate prevalence of excess intake of paracetamol and investigate seasonal variations therein.

Methods: Between 2011 and 2016, 14 481 US adults who used paracetamol in the preceding 30 days were sampled from national online panels and completed a detailed online daily diary of paracetamol medication use for 7 days. Respondents were not told that the study concerned paracetamol. Cold/flu season (CFS), identified using Google Trends data, was contrasted to off-season in symptoms, use of paracetamol medications, and consumption exceeding 4 g (the recommended daily maximum).

Results: Overall, 6.3% [95% confidence interval: 5.9-6.7%] of users exceeded 4 g on at least one day; 3.7% [3.5-3.8%] of usage days exceeded 4 g. Cold/flu symptoms were more likely to be experienced and treated with paracetamol in CFS than off-season. Paracetamol users were more likely to exceed 4 g during CFS (6.5% vs. 5.3%; odds ratio = 1.24, 1.04-1.48); days exceeding 4 g also increased (3.9% vs. 2.8%; odds ratio = 1.37, 1.11-1.69). This was not due to differences in characteristics of individuals using paracetamol in CFS, but primarily to increased use of over-the-counter combination medications designed to treat upper respiratory cold/flu symptoms (33.2% of usage days in CFS vs. 24.8% in off-season; odds ratio = 1.58, 1.46-1.72). When such medications were omitted, there was no statistically significant seasonal variation in exceeding 4 g.

Conclusions: Paracetamol use and over-dosing increases in CFS, primarily due to increased use of over-the-counter combinations treating upper respiratory cold/flu symptoms. Pharmacists should warn users to follow labelled dosing directions, especially during CFS.