Dyshidrosis is diagnosed clinically, by gathering a patient's history and making careful observations (see signs and symptoms section). Severity of symptoms can also be assessed using the dyshidrotic eczema area and severity index (DASI). The DASI has been designed for clinical trials and is not typically used in practice.

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.

Most people with rosacea have only mild redness and are never formally diagnosed or treated. No test for rosacea is known.

In many cases, simple visual inspection by a trained health care professional is sufficient for diagnosis. In other cases, particularly when pimples or redness on less-common parts of the face is present, a trial of common treatments is useful for confirming a suspected diagnosis.

The disorder can be confused or co-exist with acne vulgaris or seborrheic dermatitis. The presence of rash on the scalp or ears suggests a different or co-existing diagnosis because rosacea is primarily a facial diagnosis, although it may occasionally appear in these other areas.

Some sources claim that diaper rash is more common with cloth diapers. Others claim the material of the diaper is relevant insofar as it can wick and keep moisture away from the baby's skin, and preventing secondary "Candida" infection. However, there may not be enough data from good-quality, randomized controlled trials to support or refute disposable diaper use thus far. Furthermore, the effect of non-biodegradable diapers on the environment is a concerning matter for public policy.

Possible treatments include minimizing diaper use, barrier creams, mild topical cortisones, and antifungal agents. A variety of other inflammatory and infectious processes can occur in the diaper area and an awareness of these secondary types of diaper dermatitis aids in the accurate diagnosis and treatment of patients.

You have to treat the primary cause or the exacerbation may persisist and reincide.

Topical steroids are the primary category of medications used to treat exfoliative dermatitis (ED). A sedative antihistamine may be a useful adjunct for pruritic patients, since it helps patients to sleep at night, thus limiting nocturnal scratching and excoriations. Antimicrobial agents often are used if an infection is suspected to be precipitating or complicating exfoliative dermatitis. Other drugs specifically indicated for management of underlying cause of exfoliative dermatitis may be necessary.

To help with cradle cap, parents can gently massage their baby's scalp with their fingers or a soft brush to loosen the scales. They may want to shampoo the baby's hair more frequently (no more than once a day), and after shampooing gently brush the baby's scalp with a soft brush or a terrycloth towel. Oil remedies can be used by rubbing a small amount of pure, plant-derived oil (coconut oil, pure olive oil, almond oil) on the baby's scalp and leaving it on for 15 minutes. After 15 minutes, gently comb out the flakes with a fine tooth comb or brush. Be sure to wash out all of the oil to avoid making the cradle cap worse.

For infants: in cases that are related to fungal infection, such as Tinea capitis, doctors may recommend a treatment application of clotrimazole (commonly prescribed for jock itch or athlete's foot) or miconazole (commonly prescribed for vaginal yeast infections).

For toddlers: doctors may recommend a treatment with a mild dandruff shampoo such as Selsun Blue or Neutrogena T-gel, even though the treatment may cause initial additional scalp irritation. A doctor may instead prescribe an antifungal soap such as ketoconazole (2%) shampoo, which can work in a single treatment and shows significantly less irritation than over-the-counter shampoos such as selenium disulfide shampoos, but no adequate and controlled study has been conducted for pediatric use as of 2010.

For adults: see the article on seborrheic dermatitis (the adult version of cradle cap).

The differential diagnosis for OLP includes:

- Other oral vesiculo-ulcerative conditions such as Pemphigus vulgaris and Benign mucous membrane pemphigoid

- Lupus erythematosus, with lesions more commonly occur on the palate and appear as centrally ulcerated or erythematous with radiating white striae. In contrast, OLP and lichenoid reactions rarely occur on the palate, and the striae are randomly arranged rather than radial.

- Chronic ulcerative stomatitis

- Frictional keratosis and Morsicatio buccarum (chronic cheek biting)

- Oral leukoplakia

- Oral candidiasis

Lichen planus has a unique microscopic appearance that is similar between cutaneous, mucosal and oral. A Periodic acid-Schiff stain of the biopsy may be used to visualise the specimen. Histological features seen include:

- thickening of the stratum corneum both with nuclei present (parakeratosis) and without (orthokeratosis). Parakeratosis is more common in oral variants of lichen planus.

- thickening of the stratum granulosum

- thickening of the stratum spinosum (acanthosis) with formation of colloid bodies (also known as Civatte bodies, Sabouraud bodies) that may stretch down to the lamina propria.

- liquefactive degeneration of the stratum basale, with separation from the underlying lamina propria, as a result of desmosome loss, creating small spaces (Max Joseph spaces).

- Infiltration of T cells in a band-like pattern into the dermis "hugging" the basal layer.

- Development of a "saw-tooth" appearance of the rete pegs, which is much more common in non-oral forms of lichen planus.

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.

There are many treatments available for dyshidrosis. However, few of them have been developed or tested specifically on the condition.

- Barriers to moisture and irritants, including barrier creams and gloves.

- Topical steroids - while useful, can be dangerous long-term due to the skin-thinning side-effects, which are particularly troublesome in the context of hand dyshidrosis, due to the amount of toxins and bacteria the hands typically come in contact with.

- Potassium permanganate dilute solution soaks - also popular, and used to 'dry out' the vesicles, and kill off superficial "Staphylococcus aureus", but it can also be very painful. Undiluted it may cause significant burning.

- Dapsone (diamino-diphenyl sulfone), an antibacterial, has been recommended for the treatment of dyshidrosis in some chronic cases.

- Antihistamines: Fexofenadine up to 180 mg per day.

- Alitretinoin (9-cis-retinoic acid) has been approved for prescription in the UK. It is specifically used for chronic hand and foot eczema. It is made by Basilea of Switzerland (BAL 4079).

- Systemic steroids can be taken orally to treat especially acute and severe cases of dyshidrosis.

LSC is typically diagnosed by careful observation and history taking. It is easily recognized (see "signs and symptoms", and "gallery"). Biopsies are not necessary, and cannot be used to distinguish LSC from psoriasis.

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

Dandruff scale is a cluster of corneocytes, which have retained a large degree of cohesion with one another and detach as such from the surface of the stratum corneum. A corneocyte is a protein complex that is made of tiny threads of keratin in an organised matrix. The size and abundance of scales are heterogeneous from one site to another and over time. Parakeratotic cells often make up part of dandruff. Their numbers are related to the severity of the clinical manifestations, which may also be influenced by seborrhea.

The primary remedy for miliaria is to wear lighter clothing, move to a cooler climate, or otherwise avoid overheating one's body. The immediate treatment of the involved skin areas involves the use of a soothing ointment such as calamine lotion.

Medical assistance should be sought for the first episode of a rash with the appearance of miliaria. The differential diagnosis includes several conditions that an experienced practitioner should be able to recognise and may require treatment distinct from the usual measures taken for miliaria. In most cases the rash of miliaria will resolve without intervention. However, severe cases can last for weeks and cause significant disability. General measures should be recommended for all patients, including moving to an air-conditioned environment if possible, avoiding sweat-provoking activities and occlusive clothing, and taking frequent cool showers.

It has been suggested that the use of topical antibacterials (including antibacterial soaps) may shorten the duration of symptoms in miliaria rubra even in the absence of obvious superinfection. Other topical agents that may reduce the severity of symptoms include anti-itch preparations such as calamine or menthol- or camphor-based preparations, and topical steroid creams. However, caution should be used with oil-based preparations (ointments and oily creams as opposed to water-based or aqueous lotions) that may increase blockage to the sweat glands and prolong duration of illness. Other agents have been investigated including supplemental vitamin A and C and vitamin A based medications, but it is worth noting that there is little scientific evidence supporting any of the above treatments in reducing the duration of symptoms or frequency of complications.

In most cases, doctors will recommend that any pimple-like blisters that may form should have the fluid drained out of them (either through in-office procedure or at home in a sterile environment) to avoid the rash from spreading underneath the skin, leading to an increased state of dermatitis. Left untreated, the blisters may spread and take on an increased red appearance, with the fluid inside increasing in viscosity. It is recommended by physicians to sanitize the infected area and then drain the blisters with a sterilized needle or lancet.

In most tropical areas the local dispensaries sell prickly heat powder, a talc admixture containing drying milk proteins (Labilin) and Triclosan to fight the infection. These include cooling menthol to help alleviate difficulty getting to sleep. This is an effective treatment—the powder stays on the skin longer and treats bacteria dispersed into bed linens, providing a reasonably dry refuge area for healing. Miliaria often covers large areas, and generous use of Cortisone may be contraindicated for reasons stated on package warnings. Regular talcum powder will not reduce the rash but can alleviate burning and itching.

In cases where the rash has developed into open blisters or pustular lesions a doctor should be consulted since more aggressive, medically monitored treatment may be required.

Tinea capitis may be difficult to distinguish from other skin diseases that cause scaling, such as psoriasis and seborrhoeic dermatitis; the basis for the diagnosis is positive microscopic examination and microbial culture of epilated hairs. Wood's lamp (blacklight) examination will reveal bright green to yellow-green fluorescence of hairs infected by "M. canis", "M. audouinii", "M. rivalieri", and "M. ferrugineum" and a dull green or blue-white color of hairs infected by "T. schoenleinii". Individuals with "M. canis" infection trichoscopy will show characteristic small comma hairs. Histopathology of scalp biopsy shows fungi sparsely distributed in the stratum corneum and hyphae extending down the hair follicle, placed on the surface of the hair shaft. These findings are occasionally associated with inflammatory tissue reaction in the local tissue.

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.

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.

Shampoos use a combination of special ingredients to control dandruff.

There is no consensus about how to classify the severity of psoriasis. Mild psoriasis has been defined as a percentage of body surface area (BSA)≤10, a Psoriasis Area Severity Index (PASI) score ≤10, and a dermatology life quality index (DLQI) score ≤10. Moderate to severe psoriasis was defined by the same group as BSA >10 or PASI score >10 and a DLQI score >10. The DLQI is a 10 question tool used to measure the impact of several dermatologic diseases on daily functioning. The DLQI score ranges from 0 (minimal impairment) to 30 (maximal impairment) and is calculated with each answer being assigned 0–3 points with higher scores indicating greater social or occupational impairment.

The psoriasis area severity index (PASI) is the most widely used measurement tool for psoriasis. PASI assesses the severity of lesions and the area affected and combines these two factors into a single score from 0 (no disease) to 72 (maximal disease). Nevertheless, the PASI can be too unwieldy to use outside of research settings, which has led to attempts to simplify the index for clinical use.

Psoriasis is classified as a papulosquamous disorder and is most commonly subdivided into different categories based on histological characteristics. Variants include plaque, pustular, guttate, and flexural psoriasis. Each form has a dedicated ICD-10 code. Psoriasis can also be classified into nonpustular and pustular types.

Treatment is aimed at reducing itching and minimizing existing lesions because rubbing and scratching exacerbate LSC. The itching and inflammation may be treated with a lotions or steroid cream (such as triamcinolone or Betamethasone) applied to the affected area of the skin. Nighttime scratching can be reduced with sedatives and antihistamines. SSRIs can effectively reduce the scratching associated with obsessive psychosomatic behaviors.

Antihistamines are used primarily to reduce itching, if present. However, research studies suggest that some antihistamines have anti-inflammatory properties.

Some recommend photodynamic therapy using UV-A and UV-B laser or red and blue LED light to inhibit the growth of "Malassezia" fungus and reduce seborrhoeic inflammation.