Erythematous

The causes of erythematous rashes are as follows:

Localized erythema due to local external causes.

1. Traumatic-injury, pressure, bedsores, intertrigo, napkin rash.

2. Chemical-dermatitis and eczema.

3. Heat, cold, light-bum, frost-bite, sunburn.

4. Infective-erythema in the early stages of impetigo, insect bite

Generalized erythema, usually bilateral and symmetrical, due to a systemic internal cause.

1. Specific causes, described on etiological basis:

(a) Syphilis.

(b) Exanthemata.

(c) Drug eruption.

(d) Toxic erythema-focal sepsis, intestinal (food and its products).

2. Non-specific causes, described on morphological basis. They are definite disease entities, though the causes are indefinite.

(a) E. nodosum.

(b) E. induratum.

(c) Lupus erythematosus.

(d) E. pernio.

(e) E. multiforme.

(f) Other rare erythemas.

Erythema may take the form of localized or generalized macules or sheets. Asymmetrical, localized redness is usually due to a local, external cause. Injury produces redness; pressure may result in bedsores. Chemical and thermal bums, insect bites, bacterial infections, dermatitis and eczemas produce erythemata, at least, in the early stages. Bilateral and symmetrical widespread eruptions are usually due to an internal cause.