An experiment was carried out to determine whether caffeinated and decaffeinated coffee removed the malaise (reduced alertness, slower psychomotor performance) associated with having a common cold. One hundred volunteers were tested when healthy and 46 returned to the laboratory when they developed colds. Those subjects who remained healthy were then recalled as a control group. On the second visit subjects carried out two sessions, one pre-drink and another an hour after the drink. Subjects were randomly assigned to one of the following three conditions, caffeinated coffee (1.5 mg/kg caffeine/body weight), decaffeinated coffee or fruit juice. Subjects with colds reported decreased alertness and were slower at performing psychomotor tasks. Caffeine increased the alertness and performance of the colds subjects to the same level as the healthy group and decaffeinated coffee also led to an improvement. These results suggest that drugs which increase alertness can remove the malaise associated with the common cold, and that increased stimulation of the sensory afferent nerves may also be beneficial.