Tartrazine is a synthetic yellow food colouring made from petroleum products and you are likely to find it in things like cakes, soft drink, lollies, sauces and breakfast cereal.
It is also sometimes used in things like cough lollies and in cosmetics. People who have asthma or an asprin intolerance may be sensitive to tartrazine and experience symptoms such as hives, or itching, asthma and possibly swelling.
Tartrazine may also be linked with hyperactivity in children when it is combined with sodium benzoate. In 2014 The Australian Therapeutic Goods Administration (TGA) conducted a review in the use of tartrazine in medication because up until then it was not approved for use in oral medications.
You can read the review https://www.tga.gov.au/…/tartrazine-toxicity-1402.pdf
Use of tartrazine as a food colouring is banned in some countries and is being phased out in others. It is probably best to avoid this colourant in foods and look for foods containing beta carotene or Tumeric as a colouring instead. Or simply avoid all numbers in your food.