Incontinence associated dermatitis (IAD) refers to skin irritation and breakdown caused by exposure of the skin to urine or faeces due to incontinence
IAD represents a disruption to the normal barrier function of the skin, which triggers inflammation. Key mechanisms involved are overhydration of the skin and an increase in pH.
With incontinence, water from urine and/or faeces is pulled into and held in the corneocytes. This overhydration causes swelling and disruption of the structure of the stratum corneum and leads to visible changes in the skin. As a result of excessive hydration, irritants may more easily penetrate the stratum corneum to exacerbate inflammation. When skin is overhydrated, the epidermis is also more prone to injury from friction caused by contact with clothing, incontinence pads or bed linen
What is the stratum Corneum? The outermost layer of the skin.
pH effects on skin
pH is measured on a scale from 1 to 14 with seven being neutral, numbers above that being alkaline, and below is acidic. The usual pH range for urine is 5.5 – 7, often the lower end first thing in the morning. Urine is therefore slightly acidic. Healthy skin’s pH sits at 5.5, which helps keep infections at bay. However, with regular contact, the often-lower pH of urine can affect the skin's defence, leaving it susceptible to fungal, bacterial and yeast infections. With exposure to urine and/or faeces, skin becomes more alkaline. This occurs because skin bacteria convert the substance urea (a product of protein metabolism found in urine) to ammonia which is alkaline. The increase in skin pH is likely to allow micro-organisms to thrive and increase the risk of skin infection.
Faeces contain lipolytic (lipid-digesting) and proteolytic (protein-digesting) enzymes capable of damaging the stratum corneum. Clinical experience has demonstrated that liquid faeces are more damaging than formed faeces as liquid faeces tend to be highest in digestive enzymes. Enzymes can also act on urea to produce ammonia, further increasing the pH seen in urinary incontinence. Enzymes are more active at a higher pH, so the risk of skin damage is increased with alkaline changes. This may explain why the combination of urine and faeces observed in mixed incontinence is more irritating to the skin than either urine or stool alone.
Patients with faecal incontinence +/- urinary incontinence are at higher risk of developing IAD than those with urinary incontinence alone
Poor or inappropriate management of incontinence may also contribute to the development of IAD. For example:
- Prolonged exposure to urine and faeces due to infrequent change of incontinence products or limited cleansing
- Absorptive or incontinence containment devices may exacerbate overhydration by holding moisture against the skin surface, especially if they have a plastic backing
- Thick occlusive skin protectant products may limit fluid uptake of absorbent incontinence products causing overhydration of the stratum corneum
- Frequent skin cleansing with water and soap is detrimental to skin barrier function by damaging the corneocytes, removing lipids, increasing dryness and creating friction24
- Aggressive cleansing technique (e.g. using regular washcloths) can increase frictional forces and abrade the skin
Incontinence is a risk factor for pressure ulcers, but IAD can occur in the absence of any other pressure ulcer-associated risk factors and vice versa
All patients with urinary and/or faecal incontinence should have their skin assessed regularly to check for signs of IAD. This should be at least once daily but may be more frequent based on the number of episodes of incontinence.
Two key interventions are critical for the prevention and management of IAD:
- Manage incontinence to identify and treat reversible causes (e.g. urinary tract infection, constipation, diuretics) to reduce, or ideally eliminate skin contact with urine and/or faeces.
- Implement a structured skin care regimen to protect the skin exposed to urine and/or faeces and help restore an effective skin barrier function. These interventions will be similar for both the prevention and management of IAD