Yes, red-haired people have been reported to need more anesthesia in some studies. One source says volunteers with red hair needed higher doses of desflurane than people with dark hair, and another says red-haired individuals have a higher MAC requirement. MAC means the amount of inhaled anesthetic needed to keep someone from moving.

The sources also say this finding is not fully settled, and more research is needed. So it is best to think of red hair as a possible clue, not a rule for every person. Verify the exact plan with your surgical or anesthesia team in case they want something different for you.