Although wetness alone has the effect of macerating the skin, softening the stratum corneum, and greatly increasing susceptibility to friction injury, urine has an additional impact on skin integrity because of its effect on skin pH. While studies show that ammonia alone is only a mild skin irritant, when urea breaks down in the presence of fecal urease it increases pH because ammonia is released, which in turn promotes the activity of fecal enzymes such as protease and lipase. These fecal enzymes increase the skin's hydration and permeability to bile salts which also act as skin irritants.

There is no detectable difference in rates of diaper rash in conventional disposable diaper wearers and reusable cloth diaper wearers. "Babies wearing superabsorbent disposable diapers with a central gelling material have fewer episodes of diaper dermatitis compared with their counterparts wearing cloth diapers. However, keep in mind that superabsorbent diapers contain dyes that were suspected to cause allergic contact dermatitis (ACD)." Whether wearing cloth or disposable diapers they should be changed frequently to prevent diaper rash, even if they don't feel wet. To reduce the incidence of diaper rash, disposable diapers have been engineered to pull moisture away from the baby's skin using synthetic non-biodegradable gel. Today, cloth diapers use newly available superabsorbent microfiber cloth placed in a pocket with a layer of light permeable material that contacts the skin. This design serves to pull moisture away from the skin in to the microfiber cloth. This technology is used in most major pocket cloth diapers brands today.

The interaction between fecal enzyme activity and IDD explains the observation that infant diet and diaper rash are linked because fecal enzymes are in turn affected by diet. Breast-fed babies, for example, have a lower incidence of diaper rash, possibly because their stools have higher pH and lower enzymatic activity. Diaper rash is also most likely to be diagnosed in infants 8–12 months old, perhaps in response to an increase in eating solid foods and dietary changes around that age that affect fecal composition. Any time an infant’s diet undergoes a significant change (i.e. from breast milk to formula or from milk to solids) there appears to be an increased likelihood of diaper rash.

The link between feces and IDD is also apparent in the observation that infants are more susceptible to developing diaper rash after treating with antibiotics, which affect the intestinal microflora. Also, there is an increased incidence of diaper rash in infants who have suffered from diarrhea in the previous 48 hours, which may be because fecal enzymes such as lipase and protease are more active in feces which have passed rapidly through the gastrointestinal tract.

Women, especially those who are menopausal, are more likely than men to develop rosacea.

If the condition thickens, turns red and irritated, starts spreading, appears on other body parts, or if the baby develops thrush (fungal mouth infection), fungal ear infection (an ear infection that does not respond to antibiotics) or a persistent diaper rash, medical intervention is recommended.

Severe cases of cradle cap, especially with cracked or bleeding skin, can provide a place for bacteria to grow. If the cradle cap is caused by a fungal infection which has worsened significantly over days or weeks to allow bacterial growth (impetigo, most commonly), a combination treatment of antibiotics and antifungals may be necessary. Since it is difficult for a layperson to distinguish the difference between sebaceous gland cradle cap, fungal cradle cap, or either of these combined with a bacterial infection, medical advice should be sought if the condition appears to worsen.

Cradle cap is occasionally linked to immune disorders. If the baby is not thriving and has other problems (e.g. diarrhea), a doctor should be consulted.

The exact causes of dyshidrosis are unknown. In 2013, a randomized, double-blind, placebo-controlled cross-over study by the University Medical Center Groningen reported that dyshydrosis outbreaks on the hands increased significantly among those allergic to house dust mites, following inhalation of house dust mite allergen.

Food allergens may be involved in certain cases. Cases studies have implicated a wide range of foods including tuna, tomato, pineapple, chocolate, coffee, and spices among others. A number of studies have implicated balsam of Peru.

Id reaction and irritant contact dermatitis are possible causes.

About 1 in 2,000 people are affected in Sweden. Males and females appear to be affected equally.

Assurances that this condition will clear as the baby matures are very common. However, studies have shown that the condition occasionally persists into the toddler years, and less commonly into later childhood. It tends to recur in adolescence and persists into adulthood. In an Australian study, about 15 percent of previously diagnosed children still had eczema 10 years later. Sometimes, cradle cap turns into atopic dermatitis. Rarely, it turns out to be misdiagnosed psoriasis.

In 2007, Richard Gallo and colleagues noticed that patients with rosacea had high levels of the antimicrobial peptide cathelicidin and elevated levels of stratum corneum tryptic enzymes (SCTEs). Antibiotics have been used in the past to treat rosacea, but they may only work because they inhibit some SCTEs.

There is no good evidence that a mother's diet during pregnancy, the formula used, or breastfeeding changes the risk. There is tentative evidence that probiotics in infancy may reduce rates but it is insufficient to recommend its use.

People with eczema should not get the smallpox vaccination due to risk of developing eczema vaccinatum, a potentially severe and sometimes fatal complication.

Most cases are well managed with topical treatments and ultraviolet light. About 2% of cases are not. In more than 60% of young children, the condition subsides by adolescence.

Prickly heat can be prevented by avoiding activities that induce sweating, using air conditioning to cool the environment, wearing light clothing and in general, avoiding hot and humid weather. Frequent cool showers or cool baths with mild soap can help to prevent heat rash.

The classification of exfoliative dermatitis into Wilson-Brocq (chronic relapsing), Hebra or pityriasis rubra (progressive), and Savill (self-limited) types may have had historical value, but it currently lacks pathophysiologic or clinical utility.

Dandruff can have several causes, including dry skin, seborrhoeic dermatitis, not cleaning/scrubbing often enough, shampooing too often, psoriasis, eczema, sensitivity to hair care products, or a yeast-like fungus. Dry skin is the most common cause of flaking dandruff.

As the skin layers continually replaces itself, cells are pushed outward where they die and flake off. For most individuals, these flakes of skin are too small to be visible. However, certain conditions cause cell turnover to be unusually rapid, especially in the scalp. It is hypothesized that for people with dandruff, skin cells may mature and be shed in 2–7 days, as opposed to around a month in people without dandruff. The result is that dead skin cells are shed in large, oily clumps, which appear as white or grayish flakes on the scalp, skin and clothes.

According to one study, dandruff has been shown to be possibly the result of three factors:

1. Skin oil commonly referred to as sebum or sebaceous secretions

2. The metabolic by-products of skin micro-organisms (most specifically Malassezia yeasts)

3. Individual susceptibility and allergy sensitivity.

In contrast to cutaneous LP, which is self limited, lichen planus lesions in the mouth may persist for many years, and tend to be difficult to treat, with relapses being common. Atrophic/erosive lichen planus is associated with a small risk of cancerous transformation, and so people with OLP tend to be monitored closely over time to detect any potential change early. Sometimes OLP can become secondarily infected with Candida organisms.

According to a 2016 study, bacteria (mainly Propionibacterium and Staphylococcus) are more important to dandruff formation than fungi. Bacterial presence was in turn influenced by water and sebum amount.

Older literature cites the fungus "Malassezia furfur" (previously known as "Pityrosporum ovale") as the cause of dandruff. While this species does occur naturally on the skin surface of both healthy people and those with dandruff, in 2007 it was discovered that the responsible agent is a scalp specific fungus, "Malassezia globosa", that metabolizes triglycerides present in sebum by the expression of lipase, resulting in a lipid byproduct oleic acid. During dandruff, the levels of "Malassezia" increase by 1.5 to 2 times its normal level. Oleic acid penetrates the top layer of the epidermis, the stratum corneum, and evokes an inflammatory response in susceptible people which disturbs homeostasis and results in erratic cleavage of stratum corneum cells.

In 2016, interferon gamma/CXCL10 axis was hypothesized to be a target for treatments that reverse inflammation. Apremilast is undergoing investigation as a potential treatment .

Genetic, environmental, hormonal, and immune-system factors have been shown to be involved in the manifestation of seborrhoeic dermatitis.

Seborrhoeic dermatitis may be aggravated by illness, psychological stress, fatigue, sleep deprivation, change of season and reduced general health.

In children, excessive vitamin A intake can cause seborrhoeic dermatitis. Lack of biotin, pyridoxine (vitamin B), or riboflavin (vitamin B) may be a cause in babies.

Those with immunodeficiency (especially infection with HIV) and with neurological disorders such as Parkinson's disease (for which the condition is an autonomic sign) and stroke are particularly prone to it.

The bacteria staphylococci are present in the majority of cases. Treatment with systemic antibiotics and coal tar shampoo can completely clear the condition when Staphylococcus aureus bacteria are found. Fungal infections such as tinea capitis are known to mimic the symptoms of the condition and can be cleared with antifungal treatment.

Miliaria occurs when the sweat gland ducts get plugged due to dead skin cells or bacteria such as "Staphylococcus epidermidis", a common bacterium that occurs on the skin which is also associated with acne.

The trapped sweat leads to irritation (prickling), itching and to a rash of very small blisters, usually in a localized area of the skin.

Erythroderma (also known as "Exfoliative dermatitis," "Dermatitis exfoliativa") is an inflammatory skin disease with erythema and scaling that affects nearly the entire cutaneous surface.

In ICD-10, a distinction is made between "exfoliative dermatitis" at L26, and "erythroderma" at L53.9.

Seborrhoeic dermatitis may involve an inflammatory reaction to a proliferation of a form of the yeast "Malassezia", though this has not been proven.

The main species of yeast found on the scalp of those with the condition is "Malassezia globosa", others being "Malassezia furfur" (formerly known as "Pityrosporum ovale") and "Malassezia restricta". It has been suggested that the yeast produces toxic substances that irritate and inflame the skin. Patients with seborrhoeic dermatitis appear to have a reduced resistance to the yeast. However, the colonization rate of affected skin may be lower than that of unaffected skin.

Only saturated fatty acids (FAs) have been shown to support "Malassezia" growth. It has also been shown that while number density of "M. globosa" and "M. restricta" do not directly correlate to dandruff presence or severity, removal correlates directly with amelioration of flaking. Furthermore, in dandruff-susceptible individuals pure oleic acid, an unsaturated FA and "Malassezia" metabolite, induces flaking in the absence of "Malassezia" by direct effects on the host skin barrier. These findings support the following hypothesis:

"Malassezia" hydrolyze human sebum, releasing a mixture of saturated and unsaturated fatty acids. They take up the required saturated FAs, leaving behind unsaturated FAs. The unsaturated FAs penetrate the stratum corneum. Because of their non-uniform structure, they breach the skin's barrier function. This barrier breach induces an irritation response, leading to dandruff and seborrhoeic dermatitis.

Pustular psoriasis is classified into two major forms: localized and generalized pustular psoriasis. Within these two categories there are several variants:

Although there are likely to be multiple genetic factors and environmental triggers, mutations causing defects in the IL-36RN, CARD14 and AP1S3 genes have been shown to cause GPP .

The term pustular psoriasis is used for a heterogeneous group of diseases that share pustular skin characteristics.

This is a skin disorder characterized by a self-perpetuating scratch-itch cycle:

- It may begin with something that rubs, irritates, or scratches the skin, such as clothing.

- This causes the person to rub or scratch the affected area. Constant scratching causes the skin to thicken.

- The thickened skin itches, causing more scratching, causing more thickening.

- Affected area may spread rapidly through the rest of the body.

Many hypothesize LSC has a psychosomatic origin. Those predisposed to itch as a response to emotional tensions may be more susceptible to the itch-scratch cycle. It may also be associated with nervousness, anxiety, depression, and other psychological disorders. Many people with LSC are aware of the scratching they do during the day, but they might not be aware of the scratching they do in their sleep. LSC is also associated with atopy, or atopic dermatitis (eczema).