A teenager from Swansea has warned of the dangers of kissing, after being diagnosed with Coeliac disease.
Food that is free of gluten includes fruit, vegetables and fresh meat
Isobel Norris, 15, was told four years ago she was intolerant to gluten, and is campaigning to raise awareness of the illness.
She has produced a leaflet highlighting things sufferers must avoid, including kissing those who have consumed something containing gluten, like beer.
At least 250,000 people in the UK are known to have the disease.
But campaigners say the condition is under diagnosed.
Isobel was asked by Swansea University to make a video diary of her experiences to explain how the illness affects her every day life.
She said her intolerance to gluten - found in bread, cakes, biscuits and pastries - had dramatically affected her diet.
"I have to have gluten-free alternatives," she said. "I can get some of them on prescription but others I have to buy.
"I have to be careful of contamination in the kitchen so I have one toaster and the rest of the family has another.
"I also use separate spoons and utensils and stuff like that," she added.
Coeliac disease is caused by gluten, a protein that is found in wheat, and other similar proteins that are found in rye, barley, and oats.
In some people these proteins cause damage to the tiny projections - or villi - that line the small intestine.
Julie Norris said her daughter was on a "mission"
Villi play a significant role in the digestion process.
However, when damaged they become inflamed.
This renders them unable to absorb food properly, and can lead to diarrhoea and malnutrition.
At least 250,000 people in the UK are known to have the disease, but charity Coeliac UK claims at least 500,000 more have the illness.
Isobel, who was diagnosed following a blood test, has produced an information booklet about the disease with the help of a grant.
It includes advice about not kissing boys who have been drinking beer, for example. Beer contains wheat, which can then be transferred to the lips.
Her mother, Julie, said she was on a "mission to educate."
"She just wants much more awareness so that she can go and eat out in restaurants, and we can have family holidays that aren't always self catering," she said.