Background Non-steroidal Anti-Inflammatories (NSAID) used during exercise are associated with medical risks. Such risks include gastric side effects and renal side effects (Kuster et al, 2013). More specifically NSAIDs are implicated in the development of exercise-associated hyponatremia (Hew-Butler et al, 2015)).

Objective To identify the incidence of NSAID use in runners at the 2016 London Marathon.

Design This study will take the form of a prospective observational study.

Setting The 2016 London Marathon.

Participants Participants were recruited during the marathon registration. 109 runners completed the questionnaire. In addition, a subset of 41 runners completed an immediate pre-race questionnaire on the morning of the race, of which 28 were followed up after crossing the finish line.

Independent Variables Online and printed medical advice was available to all race participants. This included advice to refrain from using NSAIDs before and during the race was provided.

Main Outcome Measures Planned NSAID use, actual NSAID use and awareness of safe doses and NSAID risks.

Results 50 (45.9%) of the registration cohort planned to take an NSAID during the marathon. Of the athletes returning for data collection at the start line, 14 (34.1%) had already consumed an NSAID on the morning of the marathon. At the finish line, 16 of the 28 (57.1%) of athletes completing the study had consumed an NSAID. Seven runners had taken over the recommended dose of NSAID during the marathon. 13 (46%) correctly stated the risks of taking an NSAIDs, whilst only 10 (35%) were aware of the correct safe dose.

Conclusions NSAID use by runners during the marathon remains high despite published medical guidance advising against its use. Overdose of NSAIDs is a concern as it carries increased risks. A lack of awareness of the risks of taking NSAIDs may contribute towards these findings.