For some it is nuts, others wheat or maybe dairy, in fact according to the latest figures, one in three of us suffers from an allergy.
But what is to blame - and more importantly, can anything be done to help?
A conference has been taking place in Devon hoping to come up with some answers, and I have spoken to one family about the challenges of living with allergies.
At eighteen months old, Mia jones was violently sick on holiday after eating a pistachio ice cream.
She was rushed to hospital and doctors quickly ascertained it was a reaction to nuts.
Ever since, she and her parents have become extra vigilant when it comes to checking food ingredients.
Mia's mother Zorica said:
Experts at the conference say allergies are becoming more commonplace but there is a real need to educate doctors to identify the symptoms correctly.
Professor Edward Kaminsky, Immunologist said:
Mia's father Neil Jones said: