L'origine de l'érythème fessier.

Diaper Rash: What is its origin?

Redness, irritation, discomfort... Diaper rash is a common inflammation, especially in infants, due to prolonged diaper use. But what are the real causes? From moisture, friction to infections, several factors can be at play. Let's decipher together the origins of diaper rash to better prevent it.

Summary
Published March 12, 2025, updated on March 12, 2025, by Pauline, Chemical Engineer — 7 min read

How can we explain the occurrence of diaper rash?

Diaper 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 diaper 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, diaper rash can cause mild scaling or blisters. Its onset is usually gradual, evolving from a simple localized redness to a more pronounced condition if not promptly addressed. There are several causes that can lead to the occurrence of diaper rash.

  • Humidity.

    Humidity is one of the main factors that contribute to the onset of diaper rash. More specifically, it is the prolonged exposure of the skin to a moist environment that weakens the skin barrier and causes irritation. In infants, this moisture primarily comes from prolonged contact with a diaper soiled with urine or feces, which, in the absence of regular changes, maintains an occlusive environment conducive to inflammatory reactions. The skin of infants, being more fragile and 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 favorable environment for redness and, in some cases, the development of secondary infections.

  • The frictions.

    Friction is another major factor in the development of diaper rash. When the skin is subjected to repeated rubbing, particularly caused by diapers that are too tight 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 diaper rash appears.

  • Poor hygiene.

    Poor hygiene is a significant risk factor in the development of diaper rash. Indeed, the accumulation of dirt, particularly urine and feces, on the skin, creates a conducive 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 feces, such as lipase and protease, have a proteolytic effect and destroy the skin's protein structures, exacerbating the irritation. That's why preventing diaper rash involves rigorous hygiene of the buttock area, including gentle cleaning after each diaper change.

  • A reaction to a chemical product.

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

  • A bacterial or fungal infection.

    In certain instances, the diaper 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 often involved. Warm and humid environments promote its proliferation, which can lead to rashes characteristic of diaper rash. Although less common, bacterial infections can also occur. Germs, such as Staphylococcus aureus, can colonize the affected area, intensifying the inflammation and delaying healing.

If you suspect a bacterial or fungal infection, it's important to consult a doctor before the diaper rash worsens.

  • A food allergy.

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

Sources

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