Red patches on the face, legs: 7 possible causes, photos

Red patches may appear different parts of the body, sometimes in a very localized way (allergy, bites), which expands to a larger area (shingles, sunburn…) or, which can develop on several parts of the body. The conditions of appearance, the context as well as the associated symptoms (pains, burns, itching, blisters, scabs, fever, etc.) know the cause. What can cause red patches? How to make them leave?

1. An insect bite

Among the most common causes of red patches, there are insect or spider bites, immediately indicates Dr. Isabelle Rousseaux, dermatologist. Whatever the insect, its bite is manifested by the appearance ofa red bump on the skin, with a diameter varying from 1 to 15 millimetres. The pain is not necessarily immediate, nor systematic. Most insect bites, although painful, are benign. However, care must be taken not to scratch the stung area, as this can cause infection.

2. Sunburn

Sunburn is a more or less severe burn caused by the sun’s UVB rays. It is generally a first degree burn: the red patches appear on the exposed areas the 6th and 24th hour after exposure. They are due to vasodilation of the superficial cutaneous vessels. By pressing on it, the redness disappears. The burn causes pain and possibly nerve itchiness that subsides within a few days. Sometimes, sunburn can cause second-degree burns with the appearance of blisters surrounded by red patches.

3. Hives

“hives is typically an allergy that happens quite quickly. THE allergic rash following the intake of a drug (penicillin, for example) or a food is a form of urticaria. she continues. Typically the red patches caused by hives are accompanied by itching and blistering. The skin is swollen, red or pink, the border of the plaques is clear and the redness whitens when pressure is exerted with the finger. The plates are fleeting, often progressive and disappear in a few hours without leaving a trace.

4. Eczema

Contact dermatitis is another type of allergic skin reaction: “There is most often a cause and effect relationship like wearing a watch with a nickel element” points out Dr. Rousseaux. It manifests itself by red, dry, jagged-edged patches that are very itchy. Vesicles filled with clear fluid then appear. These vesicles rupture and ooze spontaneously or under the effect of scratching, linked to the severe associated itching. Crusts then form and then leave, disappearing, replaced by normal skin without scars.

5. Rosacea

Rosacea is a localized skin condition on the face that causes more or less pronounced red patches with sometimes, and it is then rosacea, edema (swelling) and vesicles. It can be accompanied by burning sensations. Rosacea affects small blood vessels that dilate.

6. Psoriasis

It is a disease where the skin renews itself at an abnormally rapid rate which leads to an excess number of skin cells (keratinocytes) and causes more or less extensive thick red patches, covered with white dead skin, the “dander”. The appearance of psoriasis depends on a number of factors: heredity, immunity, environment, taking certain medications, etc.

7. An infection (shingles, herpes…)

Red patches can also have infectious, bacterial or viral causes. They are often accompanied by fever. “Among the infectious causes, there are erysipelas which is an acute skin infection caused by streptococcus, explains Dr. Rousseaux. It appears suddenly in the form of a red, swollen and painful patch, especially on the leg.” “There are also red patches due to viruses, for example herpes where the shinglesor at Gibert pityriasis rosea.” says Dr. Rousseaux. At the start of infections, there may be only an isolated red patch and this will evolve. “We have to follow the evolution and according to it, we make the diagnosis” reports the dermatologist.

When and who to consult in case of red patches?

“It is advisable to consult if the red patches evolve, if they thicken, if they scratch, if they burn or hurt, a fortiori if you have a fever” explains Dr. Rousseaux. A consultation is also necessary if the plaques become chronic. You can consult your doctor first. This will refer you to a dermatologist if necessary, in order to refine the diagnosis. “Hives that are not progressing well can cause Quincke’s edema and you must then consult the emergency room” warns Dr. Rousseaux.

What tests to make a diagnosis?

Diagnosis of red patches is made by the attending physician and then by a dermatologist. “The questioning of the patient as well as the clinical examination will direct towards the diagnosis. If there is any doubt, there may be a biopsy in order to carry out an analysis, a blood test may also be requested”. explains Dr. Rousseaux.

What is the treatment to cure a red patch?

The treatment of red patches will of course depend on their cause: it all depends on the evolution and the context.

► In case of sunburn, Dr. Rousseaux recommends getting in the shade, cooling with water sprays, and putting on Biafine® type cream. On the other hand, “if the sunburn is more severe, if the skin blisters, you should consult for an appropriate treatment which will include nursing care”.

► In the event of an insect or spider bite, there are over-the-counter products in pharmacies but “it is advisable to consult if there is a big spider bite: the doctor will prescribe a cortisone cream and antihistamines” explains Dr. Rousseaux. It should also be checked whether circular plaques, in the shape of a target; appear around a tick bite: it may be a erythema migrans which is one of the manifestations of Lyme borreliosis. You will then be prescribed antibiotics.

► Most often, it will be appropriate toavoid self-medication when the cause of the plaques is not known. For example, you should not do not apply cortisone to shingles which requires treatment with antivirals and locally, enough to dry up the vesicles and an antibacterial cream to avoid infections.

Thanks to Doctor Isabelle rousseaux, dermatologist.