Redheads Only Become Numb Emotionally Never Physically

   Being a redhead is fun until you find out anesthesia works on you about as well as a motivational poster. 

 

The amount of times that I have been asked "is that your real hair color" while in the doctor's office is honestly impressive. I thought that redheads needing greater amounts of anesthesia was a myth until I needed my wisdom teeth taken out. Not only did I wake up twice, but when I woke up I could feel most of what was happening because the topical novocaine did not work. Just a delightful experience all around 10/10! As I have continued to have procedures that require any kind of anesthetic I have continued to have issues with pain management but... Why? The answer lies in the MC1R gene. MC1R is responsible for determining pigmentation in skin, hair, and eye color (melanocytes); the variant present in people with red hair, fair skin, and blue/green eyes is either suppressed or has loss of function (Sessler., 2015). This loss of function negatively impacts all functions of melanocytic cells, not just pigmentation. 

Research has found that a defective MC1R gene leads to a decrease in systemic melanocyte-stimulating hormone (MHS) in blood plasma in a mouse model. But what does this mean? Decreased MHS affects the baseline activity of the brain's internal opioid system- increasing the activity of the body's pain management system and thereby raising baseline pain thresholds (Robinson et al., 2021). Anesthetics must overcome the now changed baseline threshold equilibrium in order to begin taking effect.  

A study was performed by exposing 30 women with natural red hair who presented with the MC1R variant to pain stimulation compared to 30 women with darker hair without the variant. They collected baseline pain assessments for the women in each group in order to test the efficacy of local lidocaine injections & topical lidocaine cream. The results showed that the subcutaneous lidocaine injections were substantially less effective in women with red hair compared to the women with darker hair; to emphasize the degree of significance, the women with red hair were able to provide a maximum pain threshold while being exposed to the pain stimulus, whereas,  in the women with darker hair the lidocaine was so effective that researchers could not find their pain limit before the machine maxed out (Liem et al., 2005). Turns out my pain system is immune to optimism, which is honestly very on-brand. Yes, the hair is natural—the anesthesia isn’t.

     

Liem, E. B., Joiner, T. V., Tsueda, K., & Sessler, D. I. (2005). Increased sensitivity to thermal pain and reduced subcutaneous lidocaine efficacy in redheads. Anesthesiology, 102(3), 509–514. https://doi.org/10.1097/00000542-200503000-00006

Robinson, K. C., Kemény, L. V., Fell, G. L., Hermann, A. L., Allouche, J., Ding, W., Yekkirala, A., Hsiao, J. J., Su, M. Y., Theodosakis, N., Kozak, G., Takeuchi, Y., Shen, S., Berenyi, A., Mao, J., Woolf, C. J., & Fisher, D. E. (2021). Reduced MC4R signaling alters nociceptive thresholds associated with red hair. Science advances, 7(14), eabd1310. https://doi.org/10.1126/sciadv.abd1310

Sessler D. I. (2015). Red hair and anesthetic requirement. Canadian journal of anaesthesia = Journal canadien d'anesthesie, 62(4), 333–337. https://doi.org/10.1007/s12630-015-0325-z