Redheads, increased pain sensitivity, and dental anxiety: What you need to know

Many believe that people with red hair experience pain differently compared to the rest of the population. It has been reported that redheads have higher sensitivity thresholds, respond more effectively to opioid medications, and may require higher doses of anesthesia.¹

But is any of this true? And if so, what does this mean when it comes to dental pain?

Origins of red hair

Redheads have a variant of the melanocortin-1 receptor (MC1R) gene, which controls the production of melanin-thus leading to lighter hair, skin, and eye color.¹ Originally, humans had black-brown hair and brown eyes, with the MC1R variant showing up only 5,000 to 20,000 years ago. This is relatively recent if one considers the span of human existence.²

Furthermore, the "redheaded gene" is recessive, meaning a child will only be born with red hair if it inherits the MC1R gene from both parents. If they inherit the gene from only one parent, the more dominant gene will prevail, leading to darker hair. Although this gene has been linked to a higher risk of sunburn, skin cancer, and various immune system defects for both men and women, its connection to pain sensitivity is significantly higher in females.²

Redheads and pain processing

Although there is scientific evidence to support the differences in pain processing for redheaded women, the underlying reasons aren't well understood.

A 2021 study published in Science Advances used a strain of red-haired mice with the MC1R variant found in people with red hair. Researchers found that the number of melanocytes (melanin-producing cells) directly affected pain thresholds, revealing that increased pain tolerance "was caused by loss of MC1R function in melanocytes rather than other cell types."¹

The melanocytes in red-haired mice secreted lower levels of a protein which is cut into different hormones, including one that enhances pain perception and another that blocks the pain. These hormones "affect the balance between opioid receptors that inhibit pain (OPRM1) and melanocortin 4 receptors (MC4R) that increase pain sensitivity."¹

Redheads and dental anxiety

If redheads, specifically women, are more sensitive to pain and have specialized needs when it comes to anesthesia and pain medication, should dentists alter their approaches for redheaded patients? The answer is not so simple.

Despite differences in pain tolerance/sensitivity, one study found that the recovery time after surgery for redheaded patients was comparable to those with black or brown hair. There was also no difference in pain scores or the quality of recovery.³

However, another study found that redheads are more sensitive to thermal pain and were also more resistant to the analgesic effects of topical and subcutaneous lidocaine than women with darker hair.⁴

Although there has not been a significant amount of research on the relationship between redheads and dental anxiety, one report co-authored by UC Denver assistant psychology professor Abbie Beacham studied just that. Beacham and his team collected blood samples of 144 study participants ranging in hair color to determine whether those with the MC1R variant had higher dental anxiety.

According to Dr. Daniel Sessler, an outcomes research department chair at The Cleveland Clinic, in Cleveland, Ohio: "They [redheads] require more generalized anesthesia, localized anesthesia. The conventional doses fail. They have bad experiences at the dentist and because of the bad experiences, they could avoid dental care."⁵

Beacham's study found that patients with red hair were more than twice as likely to avoid dental care than others-even after the researchers factored in gender and general anxiety traits. Beacham and his team recommend that dentists keep this in mind when treating patients with red hair-and to help manage dental anxiety.⁶

If you encounter a patient with red hair in the op or dental chair, Dr. Christine Binkley of Northwestern Medicine encourages dentists to "pay more attention, evaluate everyone for dental anxiety, and ask them about previous experiences." She says, "If you know someone's anxious, do different things. Make sure they're numb before you start working on them."⁵

References

Study finds link between red hair and pain threshold. National Institute of Health. April 20, 2021. https://www.nih.gov/news-events/nih-research-matters/study-finds-link-between-red-hair-pain-threshold
Frost P, Kleisner K, Flegr J. Health status by gender, hair color, and eye color: red-haired women are the most divergent. PLoS One. 2017;12(12):e0190238. doi:10.1371/journal.pone.0190238
Myles PS, Buchanan FF, Bain CR. The effect of hair colour on anaesthetic requirements and recovery time after surgery. Anaesth Intensive Care. 2012;40(4):683-689. doi:10.1177/0310057X1204000415
Liem EB, Joiner TV, Tsueda K, Sessler DI. Increased sensitivity to thermal pain and reduced subcutaneous lidocaine efficacy in redheads. Anesthesiology. 2005;102(3):509-514. doi:10.1097/00000542-200503000-00006
Redheads have greater fear of dentists. Outcomes Research Consortium. August 29, 2009. https://or.org/what_we_have_done/redheads-have-greater-fear-of-dentists/
Study: Redheads more likely to fear dental pain. University of Colorado. August 19, 2009. https://connections.cu.edu/stories/study-redheads-more-likely-fear-dental-pain#:~:text=Redheaded%20patients%20have%20a%20genetic,the%20University%20of%20Colorado%20Denver