What does erythema mean?
Erythema is a medical term denoting abnormal redness of the skin or mucous membranes, produced when small superficial blood vessels widen and allow more blood to flow near the surface. It is not a disease itself but a visible sign that something — sun exposure, heat, infection, allergy, friction, or underlying inflammation — has irritated or injured the tissue. Clinicians describe many distinct patterns of erythema, some with specific names such as erythema multiforme or erythema migrans, the latter being a hallmark early indicator of Lyme disease. Because it is precise and widely understood across medicine, erythema appears constantly in clinical records, dermatology texts, and research papers, while ordinary speech would favor simpler words like 'redness' or 'rash'. Derived forms include the adjective erythematous, used to describe affected skin, and erythemal, found mainly in discussions of ultraviolet radiation and sunburn measurement.
nounAbnormal redness of the skin or mucous membranes, caused by increased blood flow in the superficial capillaries as a result of injury, irritation, infection, or inflammation.
- Abnormal redness of the skin caused by capillary congestion, dilation, or increased blood flow, typically a sign of inflammation, infection, irritation, or injury.
- In dermatology specifically, any reddened lesion or rash characterized by such redness, often classified by pattern (e.g., erythema multiforme, erythema nodosum).
"The doctor noted a faint erythema spreading outward from the insect bite."
"A mild erythema developed around the wound site within hours of the injury."
"The dermatologist identified the expanding ring-shaped erythema as an early sign of Lyme disease."
'Erythemas' is the common anglicized plural; 'erythemata' reflects the Greek-style plural and appears mainly in older or highly formal medical writing.
"The biopsy report documented multiple discrete erythemas across the patient's torso."
The 'sunburn' on your skin has a formal name borrowed from the ancient Greek word for red — erythros.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of erythema
Erythema derives from the Greek 'erythēma', meaning redness, which itself comes from 'erythros', the Greek word for red. The term entered English in the late seventeenth century via New Latin, as part of the wave of anatomical and medical vocabulary built on Greek roots. It shares this red-related root with modern medical terms such as erythrocyte (a red blood cell) and erythropoiesis (the production of red blood cells), all of which preserve the ancient Greek color word in scientific form.
Related word forms
How erythema is actually used
Erythema is a technical, medical register word used by clinicians and dermatologists rather than in everyday conversation; lay speakers would simply say 'redness' or 'a rash'. It carries no emotional connotation and appears chiefly in clinical notes, medical literature, and patient documentation. The adjective form 'erythematous' describes tissue exhibiting this redness.
Easily confused with erythema
Erythromycin is an antibiotic drug, whereas erythema is the clinical term for redness of the skin.