Even paddling barefoot in the sea could be fatal.
The three-year-old suffers from lymphoedema, a little known and incurable condition which causes her legs and feet to swell up dangerously.
The condition is extremely rare in children, affecting only 1 in 100,000 and Isla is thought to be the only child in Scotland born with it.
Any cuts, grazes or insect bites could be life-threatening because her lymphatic system, which helps the body fight infection, hasn't developed properly below the knees.
Holidays to popular family destinations like Spain are also out because high temperature could increase the swelling in her legs.
The little girl has to carry a little first aid kit around with her everywhere she goes with anti-bacterial medicines and a special pen.
If she gets a cut or bite, a circle must be drawn around it. If the infection grows outside the circle there is a risk she is developing cellulitis, a serious bacterial infection which can be fatal.
Mum Heather, 45, said: "Because her lymphatic system hasn't developed from the knees, if she gets a cut and it's not immediately dealt with we would have to rush her to Yorkhill.
"She has never really been barefoot. We have to be extremely careful.
"She wears special protective stockings, but when she's running around my heart is in my mouth.
"Being a three-year-old, though, nothing stops her and I've got to let her live her life."
Heather, who works for Glasgow Community Safety Services, said: "As soon as she was delivered they could see that something was wrong. There was a sense of panic amongst the nurses.
"Her wee feet and legs were really swollen. She was two weeks early and was 9lbs. I don't think anyone had seen it before.
"My thighs swelled to 60cm when I was expecting, and I was a size 10 before I was pregnant.
"They said initially it was nothing to do with it, but now they are saying it is probably genetic."
Heather and husband Andrew, 43, who live in Cambuslang, are now waiting for the results of blood tests and hope a cure may not be too far away.
Meanwhile, they spend their time fundraising for the Lymphoedema Support Network and trying to raise awareness about the condition.
The condition results from a failure of the lymphatic system to drain fluid from tissue spaces throughout the body and return it to the circulatory system.