There is a popular saying among doctors: “Be afraid of redheads and your own.” Doctors believe that red-haired people have a low pain threshold, so they need a higher dose of anesthesia, and are also more prone to bleeding during and after operations. We decided to check whether such a superstition has a scientific basis.

Many experts talk about the fear of red-haired patients. “Every ophthalmologist, especially an operating one, faces complications of postoperative treatment. And most often we are afraid to treat doctors and redheads. After all, red hair is an indicator of a mutation hidden on the 16th chromosome. Owners of fiery hair inherit unusual health and are in a special place with doctors,” - admits in the material of Moskovsky Komsomolets Svetlana Diordiychuk from the Central Military Clinical Hospital named after. Mandryk, which is part of the Russian Ministry of Defense. Obstetrician-gynecologist Stas Ivakha in the publication Life.ru tells, that if there is a red-haired patient in the operating room, he first clarifies whether her hair color is natural: “The whole point is that redheads are much more prone to bleeding. I can confirm this unequivocally. It’s rare that everything goes smoothly for a red-haired patient. They really bleed, which causes a lot of inconvenience during the operation.” At the same time, as the doctor notes, “redheads are not afraid of injections,” since “their sensitivity from such unpleasant procedures is reduced.” BBC Russian Service reports: “Doctors know: if a patient with red hair comes on duty, then, even if he is not very sick, the doctor tries to visit him more often and more. His reaction to medications can be completely unpredictable and inexplicable. He may lose consciousness from a little pain.” In the publication of the publication “Belarus Today” it says, that “anesthesia and analgesics take effect on redheads every once in a while,” which is why “the anesthesiologist needs to sweat a lot, and dentists have to use very strong painkillers.” On the tendency of red-haired patients to bleed during surgery writes and Notepad.

Natural red hair color has approximately 1–2% of the world's population. It occurs when the body produces a lot of the red pigment pheomelanin and little of the dark pigment eumelanin. For a long time, it was believed that a certain variation of the MC1R gene, which encodes the production of the melanocortin type 1 receptor protein, is responsible for red hair. However, how showed 2018 study, this characteristic is actually determined by eight other genes.

However, the biggest influence really comes from MC1R. This gene located on the long arm of chromosome 16, is also thought to be associated with sensitivity to pain and sensitivity to analgesics (drugs that relieve pain) and anesthetics (drugs that provide local or general numbness). Back in 2003, scientists from Canada's McGill University held testing the narcotic analgesic pentazocine on mutant mice with an MC1R variation similar to the variation in red-haired people. It turned out that these mice responded better to pain relief, that is, to achieve the desired effect, they required a smaller dose of the drug than normal rodents from the control group. The researchers then tested the analgesic on men and women with different hair colors. It turned out that red-haired women responded best to the drug, while red-haired men did not have such an effect - they required the same dose of the substance as blondes or brunettes. Scientists hypothesized that the MC1R variation, which gives hair a red color, is somehow related to the kappa opioid receptors, which were precisely what the drug they were testing was acting on. However, researchers found it difficult to describe the exact mechanism of influence.

In 2021, an explanation for the increased sensitivity of redheads to opioid analgesics suggested David Fisher from Massachusetts General Hospital. He found that a "red" variation in the MC1R gene in mice caused their melanocytes to produce fewer pro-opiomelanocortin (POMC) molecules. Those, in turn, are broken down into hormones, some of which can act on opioid receptors and thereby suppress pain. Accordingly, the less POMC in the body, the more sensitive opioid receptors become.

In 2004, American researchers checkedHow does the inhalation form of the anesthetic desflurane, a drug used to put a patient under anesthesia and/or maintain this state, work? Ten red-haired women and ten brunettes took part in the experiment. The depth of anesthesia was assessed through stimulation using intradermal needles. It turned out that to maintain anesthesia, redheads required almost 20% more drug than brunettes.

In 2005, the same group of scientists tested Another popular anesthetic is lidocaine, which is widely used in dentistry, ophthalmology, gynecology and cosmetology. It turned out that women with red hair are more susceptible to low and high temperatures that people with other hair colors find tolerable, and the use of a subcutaneous injection of lidocaine for them is almost half as effective in terms of pain relief. Researchers explained This is because type 1 melanocortin receptors are located not only on the surface of melanocytes, where they affect pigmentation, but also in glial cells of the brain, as well as in the periaqueductal gray matter - areas responsible for transmitting pain signals to the central nervous system. Red-haired women also have a lower pain threshold to cold stimuli noted in 2022 by researchers who analyzed a sample of more than 25,000 people.

Another group of American scientists in 2004 studied the influence of midazolam, a sedative substance from the benzodiazepine class, which is used to prepare for anesthesia during surgery. The drug also causes anterograde amnesia, which allows patients to remove unpleasant memories associated with the procedure. Volunteers in the experiment included 20 red-haired men and women, as well as 19 people with other hair colors. The researchers administered the drug to the subjects by infusion and assessed their behavior. It was found that in patients with red hair, the sedative effect of midazolam was significantly less pronounced.

In 2011, Danish scientists notedthat red-haired and light-skinned women have a higher pain threshold to certain stimuli. The researchers invited 40 volunteers: 20 women with red hair and 20 with blond or dark hair. Pain sensitivity was tested in two ways: a cream with 0.075% capsaicin (an alkaloid found in hot peppers that causes a burning sensation) was applied to the skin and pricked with pins. It turned out that in both tests, red-haired women experienced less discomfort.

Other studies, however, do not show any differences in pain tolerance between redheads and other people. In 2012, Australian scientists studied reports of operations on 468 patients, of whom 32 were red-haired. Some of them, remarkably, received the already mentioned desflurane for anesthesia. Researchers found no connection between hair color, the amount of anesthesia needed and the level of pain felt after surgery. To similar conclusions came and scientists from Washington University in St. Louis, analyzing a sample of 1,914 patients, 319 of whom were redheads.

The risk of bleeding in redheads, studies show, is no higher than the population average. In 2004, American pediatricians analyzed protocols for tonsil removal in 589 children. The amount of postoperative bleeding in redheads was the same as in patients with other hair colors. In 2006, scientists from the University of Louisville (USA) invited 25 red-haired women and 26 dark-haired women to survey their experience of bleeding and blood tests. Although respondents with red hair reported significantly more bruises after minor injuries, the researchers did not find any significant differences in their analyses. In 2011, Dutch scientists analyzed blood samples from 3,957 volunteers, 104 of whom were redheaded. The authors of the study were interested in the level of von Willebrand factor, a glycoprotein responsible for the attachment of platelets to the damaged area of the vessel. Lack or defects of this protein increase the risk of bleeding. Scientists did not find any pattern between hair color and the level of von Willebrand factor.

Thus, the fear of surgeons and anesthesiologists of red-haired patients should not be considered an empty superstition. People with this hair color are more sensitive to some types of pain and less sensitive to others. Regarding the effect of anesthetics and analgesics on such patients, the results of studies vary. But, apparently, red-haired people do not have an increased risk of bleeding.

Cover image: Image by Mohamed Chermiti from Pixabay