effect of acetaminophen, although the subsequent results have shown that it does improve performance. Conse-quently, we would like to re-emphasise that we do not con-done the use of acetaminophen in sport as a performance aid, on both safety and ethical grounds.Although we have demonstrated that acetaminophen is capable of moderating the rise in core and skin temperature during exercise in the heat (which improved time to exhaus-tion) (Mauger and hopker 2014) and that it improves cor-ticospinal excitability in resting conditions (Mauger and hopker 2013), we believe that its primary mechanism of action is through analgesia. If this is the case, then any intervention (drug, dietary or otherwise) which can reduce the sensation of pain during moderate-long, dynamic rhyth-mical exercise has the potential to improve performance. Acetaminophen is globally available, has a very high inci-dence of use and is generally considered safe at therapeu-tic doses. Conversely, other analgesics such as tramadol, diclofenac, codeine and hydrocodone are not widely avail-able (but anecdotally are widely used by amateur athletes) and pose greater threats to health and/or are highly addic-tive. therefore, we suggest that there are other analgesics, which are currently being used to improve sporting perfor-mance, which should be addressed as a priority.Professors Lippi and Sanchis-Gom highlight the defini-tion of doping, according to the International Federation of Sports Medicine, as the deliberate or inadvertent use of sub-stances or methods to produce an unfair athletic advantage. Based on this (and the research evidence we present), they suggest that acetaminophen is included in the WADA list of banned substances (subject to therapeutic Use Exception). While we do not disagree that acetaminophen is likely a performance aid, the same definition would have to apply to wide variety of substances, which are routinely used in sport to aid performance yet not currently controlled