MASD stands for moisture-associated skin damage, a term used in wound care to describe skin inflammation and breakdown caused by prolonged exposure to body fluids like urine, stool, sweat, or wound drainage. Healthy skin has a slightly acidic surface pH of about 5.5, which acts as a natural defense barrier. When moisture sits on the skin too long, it raises that pH toward alkaline levels, weakening the outer skin layer and making it vulnerable to irritation, erosion, and infection. MASD is one of the most common skin problems encountered in wound care settings, and it’s frequently mistaken for pressure injuries.
How Moisture Breaks Down the Skin
Your skin’s outermost layer, the stratum corneum, works like a waterproof seal. It stays intact partly because of its acidic pH, sometimes called the “acid mantle.” When body fluids remain in contact with the skin, they shift this pH upward. Bacteria naturally living on the skin convert urea from urine into ammonia, which dissolves in the surrounding moisture and pushes the skin’s surface toward alkalinity. That pH shift does two things: it loosens the bonds holding skin cells together, and it activates protein-digesting enzymes in stool and within the skin itself, accelerating the shedding of protective skin cells.
The result is a cascade of damage. As the barrier weakens, irritants penetrate deeper into the skin and trigger an inflammatory response, releasing signaling molecules that cause redness, swelling, and pain. The skin becomes waterlogged (a process called maceration), turning soft, pale, and fragile. Once this happens, even gentle friction from clothing or repositioning can cause the surface to erode, leaving raw, painful areas that are open to infection.
The Four Types of MASD
MASD is an umbrella term covering four distinct conditions, each defined by the source and location of the moisture involved.
Incontinence-Associated Dermatitis (IAD)
IAD is the most widely recognized form of MASD. It develops when urine, stool, or both remain in contact with the skin of the buttocks, perineum, inner thighs, or lower abdomen. In its acute phase, IAD appears as red, swollen, macerated skin with itching, burning, and pain, especially during cleaning or repositioning. On darker skin tones, the redness may instead appear as a purple discoloration. If exposure continues, blisters and vesicles can form and rupture into irregularly shaped, painful erosions. Chronic IAD looks different: the skin thickens, develops visible scaling, and may show darkened patches of post-inflammatory pigmentation.
IAD very often leads to secondary yeast infection, most commonly candidiasis. The telltale signs are white scaling, small pus-filled bumps, and “satellite” papules scattered around the edges of the inflamed area. A widely used clinical tool called the GLOBIAD categorizes IAD into two stages: category 1 (inflammation with redness but no open skin) and category 2 (inflammation with erosions).
Intertriginous Dermatitis (ITD)
ITD occurs in skin folds where opposing surfaces trap heat, sweat, and friction. Common sites include the armpits, beneath the breasts, between abdominal folds, in the groin creases, and between the toes. The Latin root of the older term “intertrigo” literally means “to rub between,” which captures the mechanics well. Skin folds run warmer than the rest of the body, and when sweat accumulates in these pockets without evaporating, the trapped moisture softens and erodes the outer skin layer.
Obesity, diabetes, excessive sweating, and incontinence all increase the risk. People with diabetes often have higher pH levels in their skin folds, making them especially susceptible. As with IAD, Candida yeast thrives in these warm, damp environments and frequently causes secondary infection. Visible pustules, crusts, or satellite lesions around the inflamed area are strong indicators that a fungal infection has taken hold.
Periwound Moisture Damage
This type affects the skin immediately surrounding a wound. When wound drainage (exudate) is excessive or poorly managed, it pools on the intact skin at the wound’s edges. The enzymes in wound fluid are biologically active, designed to break down damaged tissue as part of healing, but they don’t discriminate between wound bed and healthy surrounding skin. Over time, the periwound skin becomes macerated, inflamed, and may erode. This is a particular concern with highly exudative wounds like venous leg ulcers or surgical wounds with drains.
Peristomal Moisture Damage
Peristomal MASD develops on the skin around a stoma, the surgically created opening where digestive or urinary output exits the body. Digestive secretions have a pH significantly different from healthy skin, and that mismatch is a primary driver of the irritant contact dermatitis that develops when effluent leaks beneath an ostomy appliance. The problem tends to worsen with age, because the skin’s natural acidity declines over time, reducing the effectiveness of the ostomy skin barrier. In 2020, the Wound, Ostomy and Continence Nurses Society helped establish new diagnostic codes specifically for irritant dermatitis caused by digestive secretions and ostomy effluent, reflecting growing clinical recognition of this category.
MASD vs. Pressure Injuries
One of the most clinically important distinctions in wound care is telling MASD apart from a Stage 1 or Stage 2 pressure injury, because the two look similar but have different causes and require different treatment. Several features help distinguish them.
Location is the first clue. MASD tends to appear where moisture collects: in skin folds, along the gluteal cleft, and over the perineal area. Pressure injuries, by contrast, develop over bony prominences like the heels, sacrum, coccyx, and sitting bones, or under medical devices.
The appearance of the damaged area also differs. MASD typically presents as blotchy, diffuse, irregularly shaped patches of redness, sometimes with satellite lesions scattered nearby. A Stage 1 pressure injury shows a more defined, localized area of redness that doesn’t blanch (turn white) when you press on it, often with a noticeable change in skin temperature or firmness. A Stage 2 pressure injury exposes the deeper layer of skin (dermis), creating a shallow, pink wound with distinct margins.
The wound surface tells its own story. MASD-damaged skin looks shiny, red, and glistening, with no dead tissue (slough) in the wound bed. Stage 2 pressure injuries also appear pink and moist but tend to have cleaner, more clearly defined wound edges. Both conditions can exist at the same time, which complicates assessment, since prolonged moisture exposure also increases the risk of developing true pressure injuries.
Prevention Strategies
Preventing MASD centers on one goal: minimize the time moisture sits on the skin. For incontinence-related damage, that means prompt cleaning after each episode and using gentle, pH-neutral cleansers rather than soap and water, which can further disrupt the skin’s acid mantle. Perineal care washcloths pre-treated with a 3% dimethicone (a silicone-based moisturizer) have been studied as a combined cleansing and protective step for people with incontinence.
For wound-related MASD, proper dressing selection that matches the wound’s exudate level is key. A dressing that can’t absorb the volume of drainage a wound produces will allow fluid to pool on surrounding skin, so reassessing dressing type as a wound’s output changes is an ongoing part of care.
Treatment and Skin Protection
Once MASD develops, treatment follows a straightforward principle: remove the source of moisture, protect the damaged skin, and address any secondary infection. The protective layer is where specific products come in, and not all barriers are created equal.
Zinc oxide-based barriers received the highest level of supporting evidence in a scoping review of MASD treatments. Zinc oxide coats and physically shields the skin from moisture and irritants, forming a thick mechanical barrier. Petrolatum-based ointments are another widely used option. Petrolatum is hydrophobic, meaning it repels water, so it creates a protective seal over vulnerable skin while keeping it hydrated underneath. Solvent-based liquid polymer films, which dry into a thin transparent layer on the skin, also earned top-tier evidence ratings. These are particularly useful around wounds and stomas because they don’t interfere with adhesive dressings or ostomy appliances the way thicker ointments can.
Cyanoacrylate formulations (essentially medical-grade skin glue) offer another approach for periwound protection, forming a durable, flexible film that shields the skin from enzymatic wound drainage. The choice between these options depends on the type and location of the MASD, how much moisture is involved, and whether adhesive products need to stick to the surrounding skin.
When secondary candidal infection is present, the characteristic satellite pustules and white scaling need to be treated alongside the moisture management. Without addressing both the infection and the underlying moisture exposure, the skin damage will persist or worsen.