Erythema disappears on finger pressure (blanching), while purpura or bleeding in the skin and pigmentation do not. There is no temperature elevation, unless it is associated with the dilation of arteries in the deeper layer of the skin.

Erythema (redness) multiforme (EM) is usually a reaction of the skin and mucous membranes that occurs suddenly. It appears as a symmetrical rash and may include the mucous membrane lesions. This means that the body is sensitive to something that causes the skin and mucous membranes to react. The more common mild form is refer to as EM minor. It consists of a skin rash that involve no more than one mucosal surface. The sudden onset will progress rapidly as symmetrical lesions with circular color changes in some or all of the lesions. Rash will spread towards center or trunk of the body. Evenly distributed bumps on the skin become classic iris or target lesions. They have bright red borders and small white bumps in the center.

The cause of EM appears to be a highly sensitive reaction that can be triggered by a variety of causes. The causes can include bacterial, viral or chemical products, such as antibiotics – specifically penicillins or cephalosporins. This reaction is an allergic reaction and is in no way contagious.

Erythema multiforme minus is sometimes divided into papular and vesiulobullous forms.

The condition varies from a mild, self-limited rash (E. multiforme minor) to a severe, life-threatening form known as erythema multiformer major (or erythema multiforme majus) that also involves mucous membranes.

Consensus classification:

- Erythema multiforme minor—typical targets or raised, edematous papules distributed

- Erythema multiforme major—typical targets or raised, edematous papules distributed acrally with involvement of one or more mucous membranes; epidermal detachment involves less than 10% of total body surface area (TBSiA)

- SJS/TEN—widespread blisters predominant on the trunk and face, presenting with erythematous or pruritic macules and one or more mucous membrane erosions; epidermal detachment is less than 10% TBSA for Stevens-Johnson syndrome and 30% or more for toxic epidermal necrolysis.

The mild form usually presents with mildly itchy (but itching can be very severe), pink-red blotches, symmetrically arranged and starting on the extremities. It often takes on the classical "target lesion" appearance, with a pink-red ring around a pale center. Resolution within 7–10 days is the norm.

Individuals with persistent (chronic) erythema multiforme will often have a lesion form at an injury site, e.g. a minor scratch or abrasion, within a week. Irritation or even pressure from clothing will cause the erythema sore to continue to expand along its margins for weeks or months, long after the original sore at the center heals.

Erythema (from the Greek "erythros", meaning red) is redness of the skin or mucous membranes, caused by hyperemia (increased blood flow) in superficial capillaries. It occurs with any skin injury, infection, or inflammation. Examples of erythema not associated with pathology include nervous blushes.

The rings are barely raised and are non-itchy. The face is generally spared.

The areas most affected are the toes, fingers, earlobes, nose.

- Blistering of affected area

- Burning and itching sensation in extremities

- Dermatitis in extremities

- Digital ulceration (severe cases only)

- Erythema (blanchable redness of the skin)

- Pain in affected area

- Skin discoloration, red to dark blue

Chilblains usually heal within 7–14 days.

The typical rash commonly appears on buttocks. This then resembles the colour of a baboon’s buttocks. Other areas like upper inner thigh and armpits, may be affected by the rash. The rashes are red and well-defined. The presentation is typically symmetrical and not associated with systemic symptoms.

It occurs in less than 5% of patients with rheumatic fever, but is considered a major Jones criterion when it does occur. The four other major criteria include carditis, polyarthritis, Sydenham's Chorea, and subcutaneous nodules. In this case, it is often associated with Group A streptococcal infection, otherwise known as "Streptococcus pyogenes" infection, which can be detected with an ASO titer.

It is an early feature of rheumatic fever and not pathognomonic of it. It may be associated with mild myocarditis (inflammation of heart muscle). It is also seen in conditions like allergic drug reactions, sepsis and glomerulonephritis.

It often occurs as a harbinger of attacks in hereditary angioedema. In this case it may occur several hours or up to a day before an attack.

Localised discoid lupus erythematosus typically presents with skin lesions localised above the neck, with favoured sites being the scalp, bridge of the nose, cheeks, above the lips and ears as well as the arms hair scratching glasses touching name="Andrews1"/> Another form of discoid lupus erythematosus includes oral discoid. Oral discoid lupus erythematosus results in oral lesions which present themselves as white spots, ulcers and central erythema lesions. Oral discoid lesions most commonly occur on the labial mucosa, vermillion border and buccal mucosa. Atrophy may be observed in some cases. Dentists may be important in establishing the diagnosis before the cutaneous lesions become apparent.

The rash is composed of small papular lesions, each on a separate reddened base.

Predisposing factors include abnormal amount of subcutaneous fat, thick ankles and abnormally poor arterial supply. Abnormal arterial supply causes low-grade ischemia of ankle region. The ankle skin becomes sensitive to temperature changes. When weather is cold, ankle is cold, blue and often tender. In hot weather, ankle becomes hot, edematous, swollen and painful. Chilblains may be present. On palpation, small superficial and painful nodules are felt. They break down to form small and multiple ulcers. Fresh crops of nodules appear in periphery of ulcer and ultimately break down. In nodular stage, pain is present; while it subsides in ulcerative stage.

Erythema multiforme major (also known as "erythema multiforme majus") is a form of rash with skin loss or epidermal detachment.

The term "erythema multiforme majus" is sometimes used to imply a bullous (blistering) presentation.

According to some sources, there are two conditions included on a spectrum of this same disease process:

- Stevens–Johnson syndrome (SJS)

- Toxic epidermal necrolysis (TEN) which described by Alan Lyell and previously called Lyell syndrome[5].

In this view, EM major, SJS and TEN are considered a single condition, distinguished by degree of epidermal detachment.

However, a consensus classification separates erythema multiforme minor, erythema multiforme major, and SJS/TEN as three separate entities.

Erythema multiforme (EM) is a skin condition of unknown cause; it is a type of erythema possibly mediated by deposition of immune complexes (mostly IgM-bound complexes) in the superficial microvasculature of the skin and oral mucous membrane that usually follows an infection or drug exposure. It is an uncommon disorder, with peak incidence in the second and third decades of life. The disorder has various forms or presentations, which its name reflects ("multiforme", "", from "" + ""). Target lesions are a typical manifestation. Two types, one mild to moderate and one severe, are recognized (erythema multiforme minor and erythema multiforme major).

Chilblains — also known as pernio, chill burns and perniosis — is a medical condition that occurs when a predisposed individual is exposed to cold and humidity, causing tissue damage. It is often confused with frostbite and trench foot. Damage to capillary beds in the skin causes redness, itching, inflammation, and sometimes blisters. Chilblains can be reduced by keeping the feet and hands warm in cold weather, and avoiding extreme temperature changes. Chilblains can be idiopathic (spontaneous and unrelated to another disease), but may also be a manifestation of another serious medical condition that must be investigated. A history of chilblains suggests a connective tissue disease (such as lupus). In infants, chilblains together with severe neurologic disease and unexplained fevers occurs in Aicardi–Goutières syndrome, a rare inherited condition.

Occurring at any age these lesions appear as raised pink-red ring or bulls-eye marks. They range in size from . The lesions sometimes increase size and spread over time and may not be complete rings but irregular shapes. Distribution is usually on the thighs and legs but can also appear on the upper extremities, areas not exposed to sunlight, trunk or face. Currently EAC is not known to be contagious, but as many cases are incorrectly diagnosed as EAC, it is difficult to be certain.

Baboon syndrome affects both sexes equally, and can occur at any age, but seems to be more common in childhood than in adulthood.

Erythema toxicum neonatorum (also known as erythema toxicum, urticaria neonatorum and toxic erythema of the newborn) is a common rash in neonates. It appears in up to half of newborns carried to term, usually between day 2–5 after birth; it does not occur outside the neonatal period.

Erythema toxicum is characterized by blotchy red spots on the skin with overlying white or yellow papules or pustules. These lesions may be few or numerous. The eruption typically resolves within first two weeks of life, and frequently individual lesions will appear and disappear within minutes or hours. It is a benign condition thought to cause no discomfort to the baby.

Erythema anulare centrifugum (EAC), also known as deep gyrate erythema, erythema perstans, palpable migrating erythema and superficial gyrate erythema, is a descriptive term for a class of skin lesion presenting redness (erythema) in a ring form ("anulare") that spreads from a center ("centrifugum"). It was first described by Darier in 1916. Many different terms have been used to classify these types of lesions and it is still controversial on what exactly defines EAC. Some of the types include annular erythema (deep and superficial), erythema perstans, erythema gyratum perstans, erythema gyratum repens, darier erythema (deep gyrate erythema) and erythema figuratum perstans.

Erythema induratum is a panniculitis on the calves. It occurs mainly in women, but it is very rare now. Historically, when it has occurred, it has often been concomitant with cutaneous tuberculosis, and it was formerly thought to be always a reaction to the tuberculum bacillus. It is now considered a panniculitis that is not associated with just a single defined pathogen. The medical eponym Bazin disease was historically synonymous, but it applies only to the tuberculous form and is dated.

Erythema nodosum is characterised by nodules (rounded lumps) below the skin surface, usually on the shins. These subcutaneous nodules can appear anywhere on the body, but the most common sites are the shins, arms, thighs, and torso. Each nodule typically disappears after around two weeks, though new one may continue to form for up to six or eight weeks. A new nodule usually appears red and is hot and firm to touch. The redness starts to fade and it gradually becomes softer and smaller until it disappears. Each nodule usually heals completely without scarring over the course of about two weeks. Joint pain and inflammation sometimes continues for several weeks or months after the nodules appear.

Less common variants of erythema nodosum include:

- Ulcerating forms, seen in Crohn's disease

- Erythema contusiforme, when a subcutaneous hemorrhage (bleeding under the skin) occurs with a erythema nodosum lesion, causing the lesion to look like a contusion (bruise)

- Erythema nodosum migrans (also known as subacute nodular migratory panniculitis), a rare form of chronic erythema nodosum characterized by asymmetrical nodules that are mildly tender and migrate over time.

Discoid lupus erythematosus (DLE) is a chronic skin condition of sores with inflammation and scarring favouring the face, ears, and scalp and at times on other body areas. These lesions develop as a red, inflamed patch with a scaling and crusty appearance. The centre areas may appear lighter in colour with a rim darker than the normal skin.

Discoid lupus erythematosus can be divided into localised, generalised, and childhood discoid lupus erythematosus.

Fever and a non specific skin eruption – with reddening (erythema) and swelling (oedema) of the skin – are the most common symptoms of NEH. Patients usually present with the skin eruption 1-2 weeks after use of the cytotoxic drug. Sometimes, the skin eruption can be painful. Skin eruptions can be located on the extremities, trunk, and face. Severe lesions are rare, and can mimic cellulitis. Generalised lesions resembling erythema multiforme have been reported.

Id reactions (also known as "disseminated eczema," and "generalized eczema") are types of acute dermatitis developing after days or weeks at skin locations distant from the initial inflammatory or infectious site. They can be localised or generalised. This is also known as an 'autoeczematous response' and there must be an identifiable initial inflammatory or infectious skin problem which leads to the generalised eczema. Often, intensely itchy, the red papules and pustules can also be associated with blisters and scales and are always remote from the primary lesion. It is most commonly a blistering rash with itchy vesicles on the sides of fingers and feet as a reaction to fungal infection on the feet, athlete's foot. Stasis dermatitis, Allergic contact dermatitis, Acute irritant contact eczema and Infective dermatitis have been documented as possible triggers, but the exact cause and mechanism is not fully understood. Several other types of id reactions exist including erythema nodosum, erythema multiforme, Sweet's syndrome and urticaria.

Erythema ab igne (EAI, also known as hot water bottle rash, fire stains, laptop thigh, granny's tartan and toasted skin syndrome) is a skin condition caused by long-term exposure to heat (infrared radiation). Prolonged thermal radiation exposure to the skin can lead to the development of reticulated erythema, hyperpigmentation, scaling and telangiectasias in the affected area. Some people may complain of mild itchiness and a burning sensation, but often, unless a change in pigmentation is seen, it can go unnoticed.

The first signs of erythema nodosum are often flu-like symptoms such as a fever, cough, malaise, and aching joints. Some people also experience stiffness or swelling in the joints and weight loss.