Carmoisine (E122): The Red Azo Dye in the Southampton Six

Carmoisine (E122), also called azorubine, is a synthetic red azo dye linked to hives and itching in sensitive people. What it is, who reacts, and how to spot it.

What it is

Carmoisine, also known as azorubine or E122, is a synthetic red azo dye that gives food and drink a deep red to maroon colour. It belongs to the same chemical family as tartrazine, allura red and ponceau 4R, the azo colours that are cheap, vivid and stable, which is why they turn up so often in red and purple products. Carmoisine is one of the “Southampton Six” colours studied for possible effects on children’s behaviour, the research that led many UK and EU brands to swap artificial colours for fruit and vegetable extracts. Products that still contain it must carry the warning that it “may have an adverse effect on activity and attention in children”.

Who reacts, and how it shows on the skin

For most people carmoisine causes no skin trouble. In a minority, azo dyes act as a non-allergic trigger for hives (urticaria), the itchy, raised weals that come and go over hours, which DermNet explains are driven by histamine release from skin mast cells. People who already live with chronic urticaria are the most likely to notice a link, and for them food colours, benzoate preservatives and sometimes salicylates can each nudge an already-twitchy system. These reactions are usually dose-related rather than a true allergy, so a small amount may pass unnoticed while a lot does not, and standard allergy tests often look normal. Hives frequently appear with no clear cause at all, as the NHS points out, so a repeating pattern matters more than a one-off.

Where it hides

Carmoisine shows up in sweets, jellies, marzipan and cake decorations, red and berry-flavoured squashes and soft drinks, cheesecake and dessert mixes, some flavoured yoghurts, and occasionally in medicines and supplements where a red coating or syrup is wanted. Because brands increasingly prefer natural colours, you will meet it less often than you used to, but it still appears, especially in budget and imported ranges. On a label, look for carmoisine, azorubine or E122.

What to do

If you suspect a reaction, keep a food-and-skin diary and note red or purple sweets, drinks and desserts, watching for the same colour to line up with flares more than once before cutting anything out. Fresh, minimally processed foods naturally carry fewer added colours, which makes a useful comparison. Remember that one dye has many cousins, so a reaction to “red sweets” may involve carmoisine, allura red or ponceau 4R, and pinning down which one helps you shop with confidence. If your hives are frequent or persistent, see a GP, because recurring urticaria deserves proper assessment.

Check it against your own list

A free scanner like Yuka gives a packaged product a general health score, a useful broad read, though that verdict is the same for everyone rather than tuned to your skin, and Open Food Facts is a free, community-run database where you can look up a product’s additives and labels. To check a product against the specific things that make your skin react, a personal-list app like ClearaScan lets you save your triggers once and scan any product, food, medication or cosmetic against your own ingredient guard list, flagging only yours. Its Reaction Journal lets you tie a flare back to the product that caused it, a shared Care Circle lets family scan for you, and a Trusted Products list keeps what you have cleared, and it is currently in early access. (Disclosure: our editor co-founded ClearaScan, and we are not paid to mention the others.)