Nappy rash: what is its origin?

Nappy rash, also known as diaper dermatitis, is a common skin inflammation that primarily affects infants and young children. It presents as diffuse redness in the nappy area, often accompanied by a sensation of warmth and irritation, which can be difficult for babies to tolerate as they do not understand its origin. In some cases, nappy rash can cause mild scaling or blisters. Its onset is usually gradual, progressing from a simple localised redness to a more pronounced condition if not promptly managed. There are several causes that can lead to the occurrence of nappy rash.

• Humidity.

  Humidity is one of the main factors contributing to the onset of nappy rash. More specifically, it is the prolonged exposure of the skin to a damp environment that weakens the skin barrier and creates irritations. In infants, this moisture primarily comes from prolonged contact with a nappy soiled by urine or faeces, which, in the absence of regular changes, maintains an occlusive environment conducive to inflammatory reactions. The skin of babies, more fragile and more permeable than that of adults, is particularly vulnerable to this assault. As the moisture softens the epidermis, it impairs its barrier function, making it more reactive to friction and irritants. This prolonged maceration thus creates a favourable environment for redness and, in some cases, the development of secondary infections.

• The frictions.

  Friction is another major factor in the development of nappy rash. When the skin is subjected to repeated rubbing, particularly caused by overly tight nappies or ill-fitting underwear, it results in mechanical irritation, which disrupts the skin's surface and weakens the hydrolipidic film, this semi-aqueous, semi-oily protective veil that covers it. Irritated by this friction, the skin turns red and nappy rash appears.

• Poor hygiene.

  Poor hygiene is a significant risk factor in the development of nappy rash. Indeed, the accumulation of dirt, particularly urine and faeces, on the skin, creates a favourable environment for this type of irritation. When it breaks down, urine produces ammonia, a compound that disrupts the skin's pH, which is normally slightly acidic. This tends to weaken the hydrolipidic film and unbalance the skin microbiota. Moreover, the digestive enzymes present in faeces, such as lipase and protease, have a proteolytic effect and destroy the skin's protein structures, exacerbating the irritation. That's why preventing nappy rash involves rigorous hygiene of the buttock area, including gentle cleaning after each nappy change.

• A reaction to a chemical product.

  Some products, such as wipes or scented soaps, as well as certain treatments used for cleaning the buttocks, may contain ingredients that disrupt the skin barrier and can cause irritation, particularly on the delicate skin of babies. This initial irritation can, if not treated promptly, develop into nappy rash. That's why we recommend you opt for treatments with the simplest possible formulation, in order to reduce the risk of allergies. In children and infants, colourants, fragrances, alcohol derivatives and foaming agents should be avoided as they often prove to be irritants and can cause nappy rash.

• A bacterial or fungal infection.

  In certain instances, the nappy rash can be triggered or worsened by a fungal or bacterial infection. Among the pathogens, Candida albicans, a yeast naturally present on the skin, is frequently involved. Warm and humid environments promote its proliferation, which can lead to rashes characteristic of nappy rash. Although less common, bacterial infections can also occur. Germs, such as Staphylococcus aureus, can colonise the affected area, intensifying the inflammation and delaying healing.

If you suspect a bacterial or fungal infection, it is crucial to consult a doctor before the nappy rash worsens.

• A food allergy.

  Finally, in some instances, nappy rash may be linked to a food allergy. This reaction typically occurs in the digestive tract but, in certain cases, allergic symptoms can manifest on the skin, particularly in the nappy area. Most often, it is the food proteins found in milk that are the culprits. Nappy rash caused by a food allergy usually occurs after a repeated exposure to the trigger food. When the immune system recognises the food protein as a threat, it releases inflammatory mediators, including histamine, which can cause skin irritation. Nappy rashes caused by a food allergy are identifiable by their persistent nature: they only heal after the allergen has been eliminated.