Accounting for less than 2% of the world’s population, redheads are a rare breed. It’s by far the rarest hair colour. And they don’t always have an easy time of it. Some things, such as their skin’s sensitivity to sunlight and being the butt of other people’s jokes are potentially avoidable. Experiencing pain differently to the rest of us may not be.
Red hair is caused by a mutation in a gene called MC1R. MC1R leads to the production of a brown-black melanin pigment called eumelanin. The more eumelanin created by this gene, the darker and blacker the hair. As a result of the mutation, redheads cannot produce eumelanin, which results in the dominant pigment being the reddish-toned pheomelanin. These pigments also influence eye colour and skin tone – hence the tendency of redheads to burn easily and their greater susceptibility to melanoma.
For many years there has been anecdotal evidence that redheads perceive pain differently. It’s interesting then the MC1R gene is also responsible for the midbrain function that regulates our pain response. So, there is at least some mechanism by which this gene may also influence our response to injury and discomfort.
Over the last 20 years or so there have been a number of small-scale studies published which have examined redheads’ perception of pain. Unfortunately, the results of these studies seem conflicting. Let’s take two as an example.
A study of female redheads at the University of Louisville, published in 2004, found that redheads required nearly 20% more inhaled anaesthesia for sedation than those women with dark hair. They also found that injections of lidocaine were less effective in redheads.
Contrast this with a study published the previous year by a team at McGill University in Montreal which concluded that both male and female redheads required less morphine to dull their pain than non-redheads, while redheaded women needed less of a particular opioid for labour-pain than women with darker hair.
So, do redheads have a higher or lower tolerance to pain?
The answer to that is not straightforward. What research does suggest about redheads is that:
- To sedate them requires about 20 per cent more anesthesia;
- They are more tolerant to (so require higher doses of) local anaesthetics such as lidocaine and novocain;
- They are more sensitive to (so require lower doses of) painkillers, such as opioids;
- They more readily detect changes in hot and cold temperature;
- They may be less sensitive to electric shock, needle pricks and other stinging-type pain on the skin.
Types of pain
So redheads are more tolerant to some types of pain and less tolerant of others. But why?
It’s thought that the clue may lie in their response to the two different types of treatment for pain; anaesthesia, which makes people unable to respond to any stimulation, and analgesia, which controls pain but leaves other senses intact. Each is governed by a different part of the central nervous system.
For the time being, however, the precise reason remains unproven.
Anaesthetists are usually aware of these issues and most approach them proactively. However, they are not widely known among the medical profession more generally.
Prescriptions of opioid drugs may be a particular problem. Prescribing doctors may not be aware that redheads are often more sensitive to opioids and greater care needs to be taken in relation to dose. In the circumstances there is little option but for redheads to be proactive in drawing the issue to the attention of their GP and other clinicians.