Quinoline yellow is a yellow dye which has been used in foods. It is now known to be toxic, and is banned for that use in most countries. It causes contact dermatitis.

It is more commonly known as E104 in terms of E numbers. It is a food colourant that induces a dull yellow, or greenish yellow colour. It can be found in ices, cough sweets, scotch eggs and smoked haddock . It is one of the colours that the Hyperactive Children's Support Group recommends be eliminated from the diet of children. Whilst being a commonly used colour in the UK its use is banned in Australia, Japan, Norway and the United States.