Jo Cameron only realises her skin is burning when she smells singed flesh. She often burns her arms on the oven, but feels no pain to warn her.
That’s because she is one of only two people in the world known to have a rare genetic mutation.
It means she feels virtually no pain, and never feels anxious or afraid.
It wasn’t until she was 65 she realised she was different – when doctors couldn’t believe she didn’t need painkillers after a serious operation.
When she had surgery on her hand, doctors warned her she should expect pain afterwards.
When she felt nothing, her anaesthetist – Dr Devjit Srivastava – sent her to pain geneticists at University College London (UCL) and Oxford University.
After tests, they found gene mutations which meant that she did not feel pain like most people.
Jo, from Whitebridge, near Inverness, told the BBC Scotland news website that doctors didn’t believe her when she said she wouldn’t need pain relief after surgery.
She said: “We had banter before theatre when I guaranteed I wouldn’t need painkillers.
“When he found I hadn’t had any, he checked my medical history and found I had never asked for painkillers.”
That’s when she was referred to specialists in England.
Once diagnosed, Jo realised that she wasn’t just “incredibly healthy”, as she’d believed.
She said: “Looking back, I realise I hadn’t needed painkillers, but if you don’t need them you don’t question why you don’t.
“You are what you are, until someone points it out you don’t question it. I was just a happy soul who didn’t realise there was anything different about me.”
She didn’t even feel pain during childbirth, recalling: “It was just strange, but I didn’t have pain. It was quite enjoyable really.”