Erythema (from the Greek erythros, meaning red) is a change in colour of an area of skin, caused by increased blood flow in certain capillaries. It is a symptom common to many diseases, particularly inflammatory skin diseases.
While redness can be an obvious symptom in people with less deeply pigmented skin, where it contrasts clearly against lighter skin tones, this is not necessarily the case in those with more richly pigmented skin, for example, black, brown and olive skin tones. An example of this is sunburn, it is a common misconception that people with dark skin tones do not burn in the sun. Although it is uncommon, it can happen, but may not be easily visible. If it does occur, it may not appear as ‘redness’ that people generally associate with sunburn.
The term redness itself can be misleading, as the colour change can run the spectrum of pink, red, and purple – in some cases it may be limited to a subtle darkening of the existing skin colour.
While the signs of erythema in richly pigmented skin can be easy to miss, there are ways of spotting it. Changes in skin colouration, are often the main sign – this can be easier to spot when affected areas are compared with unaffected skin.
There is no straightforward way to predict exactly what colour erythema will look like in an individual’s skin. It is dictated by a person’s skin tone, of which there are many more variations than most people realise, and the nature of the disease in question.
Other signs, which even if not clearly visible may become more obvious upon touching the area in question, include:
- Swelling, when subtle this may be appreciated with closer inspection of the skin pores, which may become more prominent and widely spaced
- Heat, localised to the area in question
- Surface discomfort or pain, localised to the area in question
- Changes to the texture and contours of your skin
In addition to this, if you suspect that inflammation is not easy to spot on your skin then it is sensible to take into consideration other potential symptoms of your condition. For example, if you have psoriasis another common symptom to be aware of would be the appearance of scaly patches of skin.