MASD stands for moisture-associated skin damage. It refers to skin irritation and breakdown caused by prolonged exposure to moisture sources like urine, stool, sweat, wound drainage, or saliva. The World Health Organization classifies it as “irritant contact dermatitis due to friction, sweating, or contact with body fluids,” and it’s a common problem in hospitals, nursing homes, and home care settings.
What Causes MASD
Moisture alone isn’t usually enough to damage skin. The breakdown happens when prolonged wetness combines with chemical irritants in the fluid, changes in skin pH, friction from movement or clothing, and microorganisms that thrive in damp environments. Together, these factors weaken the skin’s outer barrier, making it permeable, fragile, and prone to infection.
The moisture sources responsible for MASD include urinary and fecal incontinence, perspiration, wound exudate (the fluid that seeps from healing wounds), stomal effluent (output from a surgical stoma), and saliva or mucus. Each source carries different irritants, which is why MASD is categorized into four distinct subtypes based on the type of moisture and the body area affected.
The Four Types of MASD
Incontinence-Associated Dermatitis (IAD)
IAD is the most widely studied form of MASD. It develops when urine or stool sits against the skin for extended periods, raising the skin’s pH and increasing permeability. The result is redness and swelling on the skin around the genitals and buttocks, sometimes progressing to blisters or open erosions. In the early stages, the skin often looks wet and waterlogged. Over time, it becomes dry and starts peeling. Depending on how the person is positioned, the rash can appear symmetrical or affect one side more than the other.
Reported incidence rates for IAD range from 3.4% to 50%, with the highest rates in intensive care units where patients are immobile and frequently incontinent. One of the clinical challenges with IAD is distinguishing it from pressure ulcers, since both can appear in the same areas. IAD tends to affect the raised surfaces of skin (convexities) rather than areas directly over a bony prominence, which helps differentiate the two.
Intertriginous Dermatitis (Intertrigo)
Intertrigo develops in skin folds where opposing surfaces trap heat and moisture. Common locations include beneath the breasts, between the buttocks, in the armpits, and between fingers or toes. It typically starts with itching, stinging, or a burning sensation, then progresses to redness with peeling at the edges. If a fungal infection takes hold, small raised bumps (satellite lesions) appear around the main rash. Bacterial infections can cause plaques or abscesses. Candidal intertrigo, caused by yeast overgrowth, often produces a noticeable foul smell.
Periwound Moisture Damage
This type affects the skin immediately surrounding a wound. When a wound produces more drainage than the dressing can absorb, the excess fluid sits against healthy skin, causing redness, erosion, and breakdown. The periwound area is especially vulnerable because it may already be compromised by the underlying condition that caused the wound. Keeping dressings changed before they become saturated is one of the primary ways to prevent this form of MASD.
Peristomal Dermatitis
People who have a stoma (a surgically created opening in the abdomen for waste elimination) can develop skin damage around the stoma site. The effluent that leaks beneath or around the stoma appliance is often highly irritating, particularly output from small bowel stomas, which contains digestive enzymes. The resulting skin damage looks similar to other forms of MASD: redness, swelling, and eventual erosion of the skin surface.
Who Is Most at Risk
MASD disproportionately affects people who can’t manage their own moisture exposure. That includes hospitalized patients (especially those in critical care), older adults in long-term care facilities, people with mobility limitations, and anyone managing incontinence or heavy wound drainage at home. Obesity increases the risk of intertrigo because deeper skin folds trap more heat and moisture. People with diabetes or compromised immune systems heal more slowly and are more susceptible to the secondary infections that often complicate MASD.
How MASD Affects the Skin Barrier
Healthy skin maintains a slightly acidic surface (often called the “acid mantle”) that helps fend off bacteria and fungi. When moisture sits on the skin for hours, that acidity shifts, the outermost layer of skin cells absorbs water and swells, and the tight connections between cells loosen. This process, called maceration, is the white, wrinkled appearance you see when skin has been wet for too long. Once the barrier is compromised, irritants in the moisture source penetrate more easily, friction does more damage, and opportunistic infections from yeast or bacteria can establish themselves quickly.
The combination of a weakened barrier and ongoing moisture exposure creates a cycle that’s difficult to break without removing the moisture source or protecting the skin with barrier products. Left unmanaged, MASD can progress from surface redness to open wounds that are painful, slow to heal, and vulnerable to deeper infection.
Prevention and Management Basics
The core strategy for all four types of MASD is the same: minimize moisture contact, protect the skin barrier, and address the underlying cause. For incontinence-related damage, that means prompt cleaning after each episode, using gentle pH-balanced cleansers rather than soap, and applying barrier creams or films that repel moisture while still allowing the skin to breathe. For wound-related damage, it means choosing dressings with adequate absorbency and changing them before they become saturated.
Skin fold management for intertrigo involves keeping folds dry with absorbent fabrics or moisture-wicking textiles, and treating any secondary fungal or bacterial infections that have developed. Peristomal care focuses on proper fitting of stoma appliances to prevent leakage and using skin protectants around the stoma site.
Regular skin assessments matter, particularly for people who can’t easily inspect their own skin. Catching MASD early, when the skin is just pink and irritated, makes it far easier to reverse than waiting until blisters or erosions have formed.