The popular perception that redheads have more resistance to anesthetic drugs is nothing but a myth, a new study by Melbourne researchers reveals.
They say that people with burnished locks do not behave similarly as their blond, brown or black-haired friends when they have anaesthesia in surgery.
Smaller studies of about 10 healthy, young volunteers and research involving animals had previously shown a link between red hair and anaesthesia resistance, said Melbourne anaesthetist Professor Paul Myles.
Prof Myles, from The Alfred hospital and Monash University, led a large study of 468 healthy adult patients undergoing elective surgery to investigate the theories further.
"Anaesthetists have been told for a number of years that redheads are problematic, more troublesome and need more anaesthesia," the Herald Sun quoted Prof Myles as telling a foreign news agency.
"We found in fact that redheads behave basically exactly the same as everyone else when they have anaesthesia in surgery.
"I would hope that it relieves anxiety for those that think redheads are more trouble," he added.
The difference between the recent study and previous research is that Prof Myles' team conducted its investigations on real patients, while earlier studies used animals or healthy volunteers.
Prof Myles noted, however, the results don't dispel the possibility that genetic mechanisms related to hair and skin colour is still involved in the way anaesthetic drugs work.
The gene that creates red hair, the melanocortin receptor gene, also codes parts of the nervous system.
Melanin, the pigment associated with hair and skin colour, is important in daily sleep patterns.
"There's no doubt that gene affects the sleep/wake cycle. If that's the case it's reasonable to presume that it might affect the way anaesthetics work because anaesthetics essentially induce a deep form of sleep," Prof Myles said.
The study adds to previous findings by the same researchers that gender plays a role in responses to anaesthesia.
Prof Myles said women were more likely than men to be resistant to anaesthesia and were also more sensitive to side effects, such as post-operative nausea and vomiting.
This was almost certainly linked to the female sex hormones oestrogen and progesterone, he said.
The study was published in Anaesthesia and Intensive Care.