Redheads' real pain revealed

New research indicates redheads don't feel more pain, but it is still thought they experience different effects under anaesthetics.

Funded by the Australian and New Zealand College of Anaesthetists, the study found no evidence that redheads felt more pain than patients with other hair colours.

Published in the journal Anaesthesia and Intensive Care, doctors looked at the effect of hair colour on anaesthetic requirements and recovery time after surgery.

Lead author, Melbourne anaesthetist Professor Paul Myles, said the study negated evidence from previous research which suggested redheads were less sensitive to general anaesthetics because of variants in the melanocortin-1 receptor (MC1R) gene.

"The implications of this could be quite important because it suggests redheads may be at a greater risk of waking up during surgery, as well as waking up after surgery too quickly and in pain," he said.

The study did come up with results in other areas, however.

By monitoring 468 adult patients who underwent general anaesthesia for elective surgery, researchers found there was a difference in tolerance, but between men and women, rather than redheads and non-redheads.

There were more males in the study who had black or brown hair, while a higher proportion of redheads were female - 72 per cent.

"We expected to find a small difference, with redheads waking up faster after surgery," Myles said.

"Although there was an apparent effect, it was not due to hair colour, but to gender.

"We already know that women are less sensitive to general anaesthetics and, once we accounted for gender imbalance, the effect of hair colour was negligible."

Myles said more research was needed before they could figure out how the variant in the red hair gene may influence the way anaesthetic drugs worked.

"The basic science is quite compelling and is still likely to be true," he said.

"This is because the genes that determine both the hair colour and pale skin of redheads probably influence how anaesthetic drugs act on the brain."