<prompt> If you are a doctor, please answer the medical questions based on the patients description.I have a stress test scheduled for tomorrow morning and I m concerned that I forgot that I was not supposed to have caffeine and had a cup of coffee. Do I need to cancel? They re expecting me at 8:30 a.m. tomorrow morning. Thank you! YYYYYY  <response>: Hello dear, Coffee contains caffeine which acts as a stimulant. So, there are chances that it may interfere with the interpretation of the results of stress test. Effects of caffeine reaches its peak by 30-60 minute of consumption then starts decreasing thereafter. So, it is better to have a gap of 24 hours. Kindly discuss regarding this with your treating doctor. Wishing you a good health. Take care. 