Food additives are chemicals that keep food fresh or enhance its colour, flavour or texture. Some people are sensitive to food additives, but this is rare. Reactions to food additives include hives or diarrhoea, other digestive disorders and respiratory problems such as asthma. Most food additives are listed on the product label, along with other ingredients, in a descending order by weight (flavours are an exception and do not need to be identified). Sometimes, the additive is spelt out in full. At other times, it is represented by a code number.