Redheads have long been said to feel pain differently, and dentists have traditionally treated them with some caution.1Dental Update. Redheads: Detangling the Myths The evidence points in two directions at once: redheads seem more sensitive to some kinds of pain, yet more responsive to some painkillers. So “higher pain tolerance” is less accurate than “a different pain profile,” and it traces back to the same gene that makes hair red.
Which Kinds of Pain Redheads Feel More
Temperature pain shows the clearest difference. In a lab study, red-haired women felt cold as painful at about 23°C, near room temperature, versus about 13°C for dark-haired women.2PubMed Central. Increased sensitivity to thermal pain and reduced subcutaneous lidocaine efficacy in redheads They also gave up on cold sooner, and they felt heat as painful at about 46°C, roughly 1.5°C lower than dark-haired women.3PubMed Central. Increased sensitivity to thermal pain and reduced subcutaneous lidocaine efficacy in redheads
Threshold is when something first starts to hurt; tolerance is how long you can stand it. Redheads in that study scored worse on both for cold. These are group averages, so any individual redhead could land well above or below them.
Not every study agrees. Another study of red-haired women found no difference in heat or pressure pain tolerance.4PubMed. Pain sensitivity and experimentally induced sensitisation in red haired females A review of the research describes the findings as mixed, with results depending on the type of pain tested.5PubMed Central. Red-Haired People’s Altered Responsiveness to Pain, Analgesics, and Hypnotics: Myth or Fact?—A Narrative Review So the effect, if real, looks modest and specific to some kinds of pain; a redhead may notice cold or hot pain sooner without being more sensitive to everything.
The disagreement has several likely sources. Most studies tested small groups of women only, and small studies can swing either way by chance. Different machines and pain types give different answers, and moods and expectations shift pain reports. Hair color is also a rough stand-in for the actual gene, which varies between redheads. The best-supported signal is cold and heat sensitivity, while the evidence for pain in general is weaker.
Everyday reported pain tilts the same way. Among US women, those with red hair reported more pain in daily life than dark-haired women.6PubMed Central. Natural hair color and questionnaire-reported pain among women in the United States The gap was about the same as the difference between women 6 to 7 years apart in age.7PubMed Central. Natural hair color and questionnaire-reported pain among women in the United States Blonde and light-brown-haired women also reported more pain than dark-haired women, in a smooth gradient.8PubMed Central. Natural hair color and questionnaire-reported pain among women in the United States A separate health survey, though, found no clear sign of greater pain sensitivity in red-haired women.9PubMed Central. Health status by gender, hair color, and eye color: Red-haired women are the most divergent
Why Hair Color Can Affect Pain
Most natural redheads carry changes in a gene called MC1R that leave it switched off.10PubMed Central. Invited Review MC1R, Eumelanin and Pheomelanin: their role in determining the susceptibility to skin cancer As a result, their skin makes less of the dark pigment and more red pigment, which is also why they burn easily and face a higher skin cancer risk.11PubMed Central. Invited Review MC1R, Eumelanin and Pheomelanin: their role in determining the susceptibility to skin cancer The same gene is active in nerves and the central nervous system from early development.12PubMed Central. Widespread dynamic and pleiotropic expression of the melanocortin‐1‐receptor (MC1R) system is conserved across chick, mouse and human embryonic development Some MC1R variants lower the gene’s activity in brain areas and nerves linked to pain.13PubMed Central. Detangling red hair from pain: phenotype-specific contributions from different genetic variants in melanocortin-1 receptor
“Switched off” is shorthand. MC1R is a receptor, a docking spot on a cell that receives a chemical message and passes it inward. In skin cells, a working version receives a signal that tells the cell to make dark pigment. The red-hair variants make that receptor work poorly, so the signal is weak and the cell defaults to red-yellow pigment. Many variants reduce activity rather than eliminate it, which is one reason red hair comes in different shades.
Pigment alone can’t explain the pain link. Mice with the red-hair gene variant withstand more heat and pressure before reacting, even mice with no pigment at all.14PubMed Central. Reduced MC4R signaling alters nociceptive thresholds associated with red hair So the gene seems to act on pain directly, not through hair or skin color. Hair color is a visible marker, not the cause. The gene is also part of a hormone system that sits alongside the body’s own natural painkillers, released together in the spinal cord.15PubMed. Neuropathic pain: a possible role for the melanocortin system? Mice and humans don’t fully match: the red-hair mice tolerated more heat pain, while red-haired women in one test felt heat pain sooner.
Anesthesia and Numbing Shots for Redheads
Lidocaine, the numbing drug used in dental work and minor procedures, worked less well in people with natural red hair.16PubMed Central. A Comparative Analysis of the Efficacy of Local Anesthetics and Systemic Anesthetics in the Red-Headed Versus Non-Red-Headed Patient Population: A Comprehensive Review Both the cream and the injected forms were weaker, with the injection showing the bigger difference.17PubMed Central. A Comparative Analysis of the Efficacy of Local Anesthetics and Systemic Anesthetics in the Red-Headed Versus Non-Red-Headed Patient Population: A Comprehensive Review A dental filling or stitches may therefore need extra numbing or more waiting time for a redhead.
A numb lip or cheek doesn’t always mean the nerve to the tooth is blocked, so you can feel a sharp zing from the drill even when the lip or cheek feels numb. If that happens, tell the dentist right away. They can wait a few minutes, give more, or switch to a different numbing drug.
General anesthesia is less clear. Red-haired women needed about 6.2% of an anesthetic gas versus 5.2% for dark-haired women, roughly 20% more.18PubMed Central. Anesthetic Requirement is Increased in Redheads But a study across many kinds of surgery found hair color made no difference to anesthetic needs or recovery.19PubMed. The effect of hair colour on anaesthetic requirements and recovery time after surgery The IV anesthetic propofol is usually thought to be unaffected, though one man with a red beard needed unusually high doses.20Thai Journal of Anesthesiology. Unusually High Propofol and Sevoflurane Requirements in a Patient with a Red Beard Phenotype: Bridging Clinical Practice and Literature Anesthetists monitor depth of anesthesia for every patient anyway, adjusting the dose to each person’s response, so mentioning your hair is reasonable but not cause for alarm.
Tell your dentist or anesthetist you’re a natural redhead, and mention if numbing has worn off fast before. Give your natural color, not your current one, since only the natural color hints at the gene. Say it before the injection so the dentist can plan extra time or an alternative.
Some Painkillers May Work Better for Redheads
Opioids are strong prescription painkillers related to morphine. Redheads got more pain relief from a breakdown product of morphine than others did, at the same blood levels.21PubMed Central. Melanocortin-1 receptor gene variants affect pain and mu-opioid analgesia in mice and humans So the difference comes from how their body responds, not how much drug they absorb.22PubMed Central. Melanocortin-1 receptor gene variants affect pain and mu-opioid analgesia in mice and humans Women with two copies of the red-hair variant got more relief from the opioid pentazocine than any other group.23PubMed Central. The melanocortin-1 receptor gene mediates female-specific mechanisms of analgesia in mice and humans This kind of opioid works differently in men and women in general.24PubMed. Sex differences in pain perception
Several of these findings appear mainly in women, and mouse studies also found effects mostly in females. Male redheads may have smaller or different differences, but evidence in men is thin, so their experience may vary.
Noticing pain early and responding strongly to a painkiller are different processes, so both can be true in the same person. If you are prescribed a painkiller, take it as directed and tell your doctor how well it works, rather than adjusting the dose yourself.
Does It Apply to Every Redhead
Fully red hair often reflects two altered copies of the gene, while a red beard with other-colored hair often reflects one, though hair color is only a rough guide.25Thai Journal of Anesthesiology. Unusually High Propofol and Sevoflurane Requirements in a Patient with a Red Beard Phenotype: Bridging Clinical Practice and Literature The strongest painkiller effect was seen in women with two copies.26PubMed Central. The melanocortin-1 receptor gene mediates female-specific mechanisms of analgesia in mice and humans Someone with auburn hair or only a red beard may therefore show weaker or no differences. Some people also carry the variants without obviously red hair, since hair color is a rough guide. Only natural hair color reflects the gene, so dyeing hair red doesn’t create any pain difference, and a redhead who dyes their hair brown still carries the same variants.
Redheads and Fear of the Dentist
About 46% of redheads in one study avoided dental care, versus 27% of dark-haired people.27PubMed Central. Genetic variations associated with red hair color and fear of dental pain, anxiety regarding dental care and avoidance of dental care People with the red-hair gene variants were more than twice as likely to skip routine visits, even after accounting for general anxiety.28PubMed Central. Genetic variations associated with red hair color and fear of dental pain, anxiety regarding dental care and avoidance of dental care Skipped checkups can turn small problems into painful, bigger ones. A filling that wasn’t fully numbed can make the next appointment feel frightening before it begins, and fear itself can raise how much pain a person feels.
To get care comfortably, book with a dentist who will discuss numbing options in advance. Agree on a hand signal to stop if you feel pain. If lidocaine has failed before, ask about longer numbing time or alternative drugs.