Why Redheads May Need More Anesthesia

Question for the redheads: Do you ever find yourself asking for extra novocaine during dental procedures?

You’re not alone. Experts have long suspected that people with red hair need more anesthetic drugs to get the same results as people with other hair colors.

“Red hair is the only physical characteristic that indicates how much anesthetic a person needs,” says anesthesia researcher Daniel Sessler, MD. “Redheads report more pain during procedures. Some studies also show that people with red hair are more resistant to local anesthetics. And they may need more general anesthesia to keep them sleeping during medical procedures.”

Most of the research on this topic is older and limited. That may be because less than 2% of people worldwide have naturally red hair. But as experts do more modern and robust research, they’re learning more about the genetics associated with red hair and anesthesia.

Do redheads need more anesthesia?

Experts have studied pain in redheads since the early 2000s. But the research really took off around 2004, when an article in the journal Anesthesiology reported that people with red hair and the MC1R gene mutation needed as much as 20% more anesthesia. Several studies backed these findings up (and elaborated on them) in the decades since its publication. More on them in a bit.

But the results haven’t always been consistent. For example, a 2012 paper found no association between red hair and anesthesia effectiveness. Another study, this one from 2020, reported that red hair and pain sensitivity may come from two unrelated genetic changes (mutations).

The research isn’t conclusive, but experience is a form of evidence. And it’s hard to ignore all the anecdotal data that suggests anesthetics aren’t as effective on people with red hair.

“The good news is that red hair or not, you’ll get the amount of general anesthesia that’s right for you,” Dr. Sessler reassures. “Anesthesiologists are experts at giving people the right amount of medication to keep them comfortable during a procedure. They’ll adjust anesthetics as needed for your specific situation,” he says. “No anesthesiologist gives everyone the same dose.”

Want to better understand the research on red hair, pain sensitivity and anesthetics? Dr. Sessler gives us the rundown.

The ‘redhead gene’ may be connected to pain sensitivity

The same gene that gives someone fiery locks may also lower their pain tolerance. The melanocortin 1 receptor (MC1R) gene produces melanin, a pigment that gives color to skin, eyes and hair. But people with red hair have an MC1R gene mutation. As a result, it produces the red pigment pheomelanin instead of melanin, which is black.

“Redheads are the only people with this gene mutation,” Dr. Sessler clarifies. “But MC1R is just one type of melanocortin receptor. Other types relate to brain function. And the mutation that affects MC1R may also affect those other melanocortin receptors.”

Natural redheads may need more anesthesia during surgery

Both nonhuman and human studies report the need for more anesthesia in redheads. The 2004 study that did the most to establish this link examined gas anesthesia in people with red hair compared to those with dark hair.

Though the study was small, researchers concluded that people with red hair and the MC1R gene mutation needed as much as 20% more anesthesia.

A 2004 nonhuman lab study with the MC1R mutation also recognized the need for additional anesthetic to achieve the same sedation.

“Of course, people with blond, brown or black hair will also vary in how much anesthesia they need. The dose must be personalized for you. But in general, people with red hair require more anesthetic than people with other hair colors,” Dr. Sessler shares.

Local anesthetic may not be as effective on redheads

The Journal of the American Dental Association reports that people with naturally red hair tend to fear dental care more than others. The reason may be related to pain and how well local anesthetic (used for numbing tissue) works for redheads.

A commonly used local anesthetic is lidocaine, which can administered topically as a cream or gel or injected just below the skin. A 2003 study found that both forms of lidocaine were less effective in people with red hair, with the injected lidocaine showing the most significant difference.

“It’s reasonable to inform or remind your dentist that you may need more local anesthetic,” Dr. Sessler says. He also advises redheads that local anesthesia may take longer to kick in. Waiting an extra few minutes may make the anesthetic more effective and reduce dental pain.

Redheads may be more sensitive to some (but not all) types of pain

In 2003, researchers observed that people with red hair didn’t have an increased sensitivity to electrical stimulation compared to people with dark hair. But they had a higher sensitivity and lower tolerance for cold and heat pain.

“There are many types of pain, and we’ve only tested a couple,” Dr. Sessler says. “But we have a better understanding of how redheads might tolerate temperature and electrical stimulation pain factors associated with surgery.”

Tips for redheads who need an anesthetic

If you have naturally red hair, Dr. Sessler recommends that you:

• Don’t let your fear of pain keep you from receiving healthcare. Not getting the dental or medical care you need will only cause more problems — and pain — in the future.
• Talk to your doctor or dentist. Most medical and dental students don’t learn about this topic in medical school. Inform your provider of your concerns, especially if you’re a natural redhead.
• Wait longer for local anesthetics to kick in. You may need more anesthetic, but you also may need to wait longer for a local anesthetic to take effect.

“Don’t avoid medical or dental care, even if you’ve had an uncomfortable or painful experience in the past,” Dr. Sessler emphasizes. “Your healthcare provider will personalize your care, including the amount of anesthetic you need.”