By Amy Norton
New York - The dyes used to give nappies a fashionable flair may also give some babies and toddlers an allergic skin reaction, according to doctors.
In the September issue of the journal Pediatrics, they describe the cases of five children whose colourful nappies and training pants caused their skin to become red, itchy and inflamed.
The babies and toddlers, who ranged in age from nine months to three years, were all diagnosed with allergic contact dermatitis - a reaction that arises when the skin comes in contact with an allergy-provoking substance, which in these cases appeared to be fabric dye.
All of the children improved after their parents switched to dye-free nappies.
Nappy rash is a common affliction of nappy wearers, but nappy dyes are a little recognised source of skin irritation, according to Dr Karen Wiss of the University of Massachusetts Medical School in Worcester.
For parents, location is the "best clue" as to whether their baby's nappy rash is an allergic reaction to dye, Wiss said. If the skin irritation lines up with coloured areas of the child's nappy, the dye may be to blame.
In one of the cases Wiss and her colleagues describe, a two-year-old boy developed hives underneath the blue-dyed waistband of his diaper.
In another, a nine-month-old had a "well-demarcated" rash that matched up with the green-coloured areas of his nappy.
Two of the children underwent skin testing that confirmed they had allergies to so-called disperse dyes. These dyes, which are used to colour synthetic fibres like polyester, may release from fabrics in the presence of friction and sweating, Wiss and her colleagues note.
Still, though these cases call attention to the potential for nappy-dye reactions, Wiss said that the "vast majority" of babies and toddlers can probably wear colourful nappies without a problem.