The purpose of this study was to examine nurses' use and knowledge of caffeine and high energy drinks (HED) in three countries. Nurses in each country completed a survey on caffeine and HED use and knowledge. In a sample of 182 nurses, caffeine use was high with 92% of nurses in Korea, 90.8% in Italy and 88.1% in the United States (US) having at least one cup of coffee a day while 64% of Koreans and 11.9% of those in the US had at least one HED per day. In Korea 68% of nurses (Italy 63.1% and 35.8% US) had at least one cup of caffeinated tea per day. Most agreed there is a need to educate nurses about HED, which contain high amounts of caffeine. Over half of nurses in Korea (58%) and the US (56.7%) said their colleagues consume HED at work. Findings of this study indicate many nurses are consuming caffeine at work and there is a need for education. It is unclear how caffeine affects nurses' clinical performance, which raises the issue of patient safety. Further research is needed regarding safe amounts of caffeine while nurses are on the job as well as an understanding of how HED additives may affect the well-being and clinical care of nurses. •Caffeine is a frequently consumed stimulant.•High energy drinks (HED) contain large amounts of caffeine and their use is rising.•Nurses in the study and their colleagues are consuming caffeine and HED at work.•Findings indicated there is a need to educate nurses about HED.•Future studies should assess the effects of caffeine on nurses' clinical care.