The trial will recruit 400 eligible patients over 1 year (200 Penthrox and 200 tramadol). 200 samples of Penthrox will be provided free of charge by Medical Developments International (MDI), an Australian company, for evaluation during the trial. Patients managed by SCDF EAS for treatment of acute pain and who meet the eligibility criteria will be recruited into the study. Intramuscular tramadol will be purchased by SCDF for this implementation trial.