AbstractObjective:Co-Phenylcaine Forte is a nasal spray routinely prescribed by otolaryngologists in Australia. The taste of Co-Phenylcaine Forte is typically described as unpleasant. This study sought to improve the overall patient experience associated with Co-Phenylcaine Forte by generating a Co-Phenylcaine Forte formulation, referred to as Co-Phenylcaine Zest, which contains an added vanilla flavour and masking agent.Methods:Participants were randomised to receive two actuations of Co-Phenylcaine Forte in each nostril followed by two actuations of Co-Phenylcaine Zest, or vice versa. There was a 6–36-hour washout period between each treatment. After the administration of each spray, participants completed a questionnaire to rate various sensory attributes of each formulation on seven-point ordinal scales. Patients reported their overall formulation preference after receiving both treatments.Results:A total of 86 participants completed the trial. Seventy-four per cent of patients preferred Co-Phenylcaine Zest, 21 per cent preferred Co-Phenylcaine Forte and 5 per cent had no preference (p < 0.001). The satisfaction score associated with Co-Phenylcaine Zest was 1.22 points greater than with Co-Phenylcaine Forte (p < 0.001).Conclusion:A novel formulation of Co-Phenylcaine Forte was created by adding a flavour and a masking agent; this formulation was preferred by most patients.