Individuals with red hair often have a genetic variation in the melanocortin-1 receptor (MC1R) gene, which is responsible for producing the pigment that gives hair its red color. This genetic variation can also affect how the body responds to certain types of anesthesia and pain medications. There is a study which shows on average those with red hair may require around 20 percent more anesthesia. Of course an individual's response to anesthesia is also influenced by many factors including geneti