Redheads extremely sensitive to pain

http://www.baffledbaboon.com/5-strange-facts-about-hair/

5. Redheads feel more pain
If I had to choose between being a blonde or a redhead, I would definitely go with blonde. Only because having a silly personality is way better than being extremely sensitive to pain. If you’re a redhead, you probably dread going to the dentist more than others – and for good reason. Standard painkillers don’t work nearly as well on redheads as they do on blondes or brunettes, and they may need higher doses of painkillers than usual to get the desired effect. But being a redhead isn’t all bad! Redheads don’t seem to develop grey hairs – instead turning blondish/pure white as they age.

http://healthland.time.com/2010/12/10/why-surgeons-dread-red-heads/

For those few who do have the redhead phenotype, the physical challenges go beyond the occasional sunburn — something that surgeons well know. And that’s what the BMJ authors sought to explore in their meta-analysis, or survey of the existing scientific literature

Operating room docs, for example, have long reported that redheads appear to need more anesthetic than others. The new study suggests that that observation is an accurate one — mostly. Those with the MC1R mutation are more sensitive to opiate pain killers — which means they’d actually need less — but less sensitive to other types, most notably lidocaine injections. One study which used heat-related pain as its litmus of overall sensitivity showed that redheads indeed felt things more acutely and unpleasantly, probably because the MC1R mutation releases a hormone that stimulates a brain receptor associated with pain regulation…