Home Symptoms Rash (eczema, exanthema) – signs, causes, help

Rash (eczema, exanthema) – signs, causes, help

by Josephine Andrews
Published: Last Updated on 268 views

skin rash (exanthema) can appear suddenly on different parts of the body and look very different: spots, blisters or scales can form on the skin, for example. Infectious diseases such as chickenpox or measles can be behind the rash, but also allergies or various skin diseases – such as psoriasis or neurodermatitis. Here’s what rash can mean and how it’s treated.

quick overview

  • Description: Reaction of the skin to external or internal influences; manifests itself in itching, redness, blisters, nodules, weeping, etc.
  • Causes: various, e.g. B. Infectious diseases (measles, scarlet fever, rubella , ringworm , hand-foot disease, Lyme disease, shingles, skin fungus, scabies , syphilis , typhus , typhus, dengue fever , etc.), allergies (such as contact allergy), medication, skin and Autoimmune diseases ( acne , neurodermatitis, psoriasis etc.), psychological factors
  • When to see a doctor: e.g. if the rash is severe, changes, the cause is unclear, is extremely itchy or painful, is spreading, additional symptoms occur
  • Diagnosis: by talking to the patient, physical examination, if necessary skin swab, tissue removal, blood test, allergy test
  • Therapy: depending on the cause, e.g. B. with antibiotics, antivirals , antihistamines, immunosuppressants, etc.; usually local treatment with ointments or creams

Rash: description

Human skin consists of around two billion skin cells that protect the body from pathogens and solar radiation, but also from overheating, excessive heat loss and dehydration. The skin is also the body’s largest organ: in an adult, it covers an area of ​​around two square meters and weighs a whopping ten kilos in total.

The skin usually reacts immediately and clearly to external and internal influences – with nervousness or shame with blushing, with nausea with pallor, with stress often with pimples or sometimes with a rash that can spread to smaller or larger areas of the skin. The medical term efflorescence means “skin change”. In principle, the skin changes can affect the whole body, but they can also be limited to individual areas, in which case experts also speak of an exanthema. Some people have a rash on their face, others on their fingers, hands, knees, legs, feet, toes, elbows, forearms, abdomen, or back. The mucous membranes in the mouth and throat or the skin on the genital organs can also be affected.

For example, the rash may consist of colored patches, fluid-filled blisters, pustules, hives, or nodules. Based on the appearance of the rash, dermatologists can often deduce the cause. Itching is a very common symptom accompanying skin rashes. However, the rash can also burn or cause pain or warmth.

Although eczema also manifests itself in skin rashes, they are always based on skin inflammation. Specifically, “eczema” is a collective term for inflammatory skin diseases that are not contagious. In principle, external or internal factors can cause eczema.

Rash: causes and possible diseases

Skin rash can have many different causes. For example, infections such as chickenpox or measles, allergies and various skin diseases such as psoriasis or neurodermatitis can be behind it.

infectious diseases

Three -day fever (exanthema subitum) is a contagious disease caused by viruses . Along with the high fever , a patchy, red, itchy rash develops on the chest , abdomen, and back. It can spread to the arms and legs but will go away after a few days.

Scarlet fever (Scarlatina) is a typical childhood disease caused by an infection with bacteria (streptococci). Typical is, among other things, the skin rash, which is caused by the toxins of the bacteria. It starts with small reddenings in the creases of the armpits, on the chest and in the groin region and spreads over the whole body. Typically, only a small triangle between the chin and mouth and the palms of the hands and soles of the feet remain free of rashes. In some patients, the rash is absent or only mild. After about a week, after three at the latest, the rash disappears completely.

Measles is another childhood disease caused by viruses. It is highly contagious and spreads rapidly. A rash is also characteristic of measles. Red, irregular spots appear behind the ears and on the side of the neck, which soon merge and cover the whole body. Minor skin bleeding may occur. The rash goes away after about five days.

Rubella is caused by a viral infection. The rash starts here behind the ears with small bright red or slightly brownish spots. They spread to the face, neck, arms, legs, and then to the entire body. However, unlike measles, they do not fuse. Itchy rashes are also rare with rubella. The rash will disappear after one to three days.

Ringworm (erythema infectiosum) is an infectious disease caused by the parvovirus B19. The butterfly-shaped rash is characteristic here, but this does not develop in all patients. The rash first appears on the face (cheeks, bridge of the nose) and after a few days spreads to the arms, legs (especially the extensor sides) and finally the entire body. The rash looks like a garland and can vary in severity. The rash can reappear over a period of seven weeks.

Hand , foot and mouth disease is caused by Coxsackie virus type A. A red, itchy rash with blisters and nodules forms on the skin (hands, feet), which later turns into white-grey pustules. Blisters and small, painful ulcers ( aphthous ulcers ) develop in the mouth.

Glandular fever can sometimes cause a skin rash. However, it can also develop if the disease is treated with antibiotics, such as ampicillin or amoxicillin . One then speaks of a drug eruption .

Lyme disease is an infectious disease that is usually transmitted by ticks. Lyme disease is caused by screw-shaped bacteria known as Borrelia. After a few days, a red spot may appear around the puncture site, which gradually enlarges and is usually pale in color in the middle. Doctors refer to this as “migratory blush” or erythema migrans.

Chickenpox (varicella) is caused by the highly contagious varicella-zoster virus . They start with an itchy, red rash – usually on the trunk and face. It spreads all over the body, including the hairy part of the head, arms, and legs.

The mucous membranes (mouth, conjunctiva, genitals) can also be affected. The red spots turn into fluid-filled, very itchy blisters that gradually crust over. The rash progresses in phases, so that new red spots appear every day in addition to the existing skin blisters and scabs. A so-called “starry sky” forms: a colorful picture of spots, papules, vesicles and crusts that eventually fall off. On the mucous membranes, the vesicles turn into small aphthae (= damage).

Shingles (herpes zoster) is a painful skin rash caused by the varicella zoster virus. Shingles is a secondary disease: the herpes virus causes chickenpox on first contact, it persists in the body after the disease has subsided and can become active again years later: in the form of shingles. The typical rash consists of blisters on a swollen, red surface.

The rash usually runs belt-like on the trunk and extends, for example, from the back towards the breastbone. But it can also cause a rash on the face and ears . After two to seven days, the blisters burst, small wounds appear that are gradually covered by scabs. The scab usually falls off after two to three weeks.

Genital herpes ( herpes genitalis ) is caused by the herpes simplex virus (HSV). An itchy rash with redness and blisters forms on the skin in the genital area. If they occur in the area of ​​the lips, one speaks of cold sores. In some cases, HSV causes a painful rash in the mouth (mouth ulcers/aphthous stomatitis).

Skin fungus (thrush) includes all diseases caused by fungi of the genus “Candida”. The main representative is Candida albicans. The rash occurs particularly in skin folds (e.g. armpits, anal region, thighs), on the mucous membranes of the mouth and throat, in the esophagus and in the genital region (in the form of vaginal thrush or penis thrush ).

The erysipelas is a locally limited, acute inflammation of the lymphatic vessels of the skin. A erysipelas is usually caused by certain bacteria (streptococci). The bright red erysipelas forms around the entry point of the bacteria into the skin.

The scab lichen (bark lichen, impetigo contagiosa ) is a bacterial skin infection that is very contagious. The main causes are staphylococci, more rarely streptococci. Typical of the skin rash are asymmetrical, sharply demarcated, golden-yellow, red-lined crusts, which appear primarily around the mouth and nose and on the hands.

Scabies is caused by mites that cause an intensely itchy rash.

Syphilis is a sexually transmitted disease caused by the bacterium Treponema pallidum. In the second stage of syphilis, a rash usually appears. At first they are only pale pink spots that turn into rough, copper-colored nodules (papules).

Inflammation of the liver (hepatitis) caused by a virus is sometimes accompanied by a skin rash.

Typhus (typhus) is caused by the bacterium Rickettsia prowazekii, which is transmitted by body lice. A patchy rash develops after a few days, starting on the torso and quickly spreading to the arms and legs – but the head, neck, palms of hands and feet remain without exanthema.

Typhoid is a severe diarrheal disease caused by bacteria (salmonella). Here, too, reddish spots the size of a pinhead can form on the abdomen, chest and back, but they do not itch.

A rubella- like, itchy rash can also occur temporarily in dengue fever . This tropical disease is caused by the dengue virus.


An allergy is a hypersensitive reaction to certain substances that are normally completely harmless. The immune system fights these harmless substances and thus triggers an allergy. Examples are pollen ( hay fever ), but also food or chemical substances such as nickel or cobalt. Reddening of the skin and an itchy rash are common signs of an immediate allergic reaction . This means that the allergy begins a few seconds to minutes after contact with the allergy trigger (medical allergen).

In the case of a late-type allergy , sharply demarcated, itchy redness and swelling only develop after a few hours. Depending on the severity, water blisters, weeping spots, dandruff and skin encrustations appear.

The allergy-triggering substances can have a direct external effect on the skin (such as UV radiation, cold). However, they can also have a skin-irritating effect on the inside by being inhaled or ingested with food. This is the case, for example, with hay fever and food allergies such as nut allergies. Medications can also cause a rash and other allergic symptoms.

Another typical form of late-type allergy is contact allergy (contact dermatitis). It occurs when the skin comes into contact with the allergy-causing object or material. These are often fragrances or metals such as nickel. Even the smallest amounts are often enough to cause an allergic reaction. The skin then becomes itchy, swollen, weeping or reddened. The skin rash (eczema) usually develops on the area that was in contact with the allergy trigger (contact eczema). Above all, allergies to fragrances are on the rise. The symptoms: rough, reddened or scaly skin and itching. If the allergen acts on the skin for a longer period of time, blisters, nodules and painful tears can develop.

Hives (nettle rash, urticaria) are also among the allergic diseases . The rash here consists of red bumps. They look like mosquito bites or after exposure to stinging nettles (hence hives).

Patients with hives are hypersensitive to certain internal (food such as strawberries) or external (cold, pressure) stimuli. You suffer from severe itching. Most of the time, both the wheals and the itching go away within a day.

Sunlight can also trigger strong allergic skin reactions. Excruciating itching, blisters or wheals (sun allergy) occur. This often happens in combination with cosmetics such as skin and sun cream or perfume. Polymorphic light eruption (PLD) is the most common of all sun allergies . It mainly occurs on areas of the skin that are not yet used to the sun, such as the décolleté, shoulders, neck, extensor sides of the arms and legs. PLD usually manifests itself with wheals, itchy spots or blisters.

In the case of Mallorca acne , aggressive substances that form as a result of UV light react with ingredients in sunscreen and body care products or the body’s own sebum. An inflammatory reaction develops in the hair follicles. This leads to acne-like pimples on the skin – mostly in the décolleté.

In combination with medications such as antibiotics, anti-inflammatories, diuretics or St. John’s wort   , sunlight can trigger a photoallergic reaction .

Sunburn is also one of the exanthems.

skin diseases

A skin rash can also be caused by various skin diseases that are not contagious. Examples:

Acne is a hormone-related disease that mainly depends on the male sex hormones (androgens). It often occurs during puberty. Typical are the white nodules, which sometimes also have a black dot in the middle (blackheads, comedos). If the nodules become inflamed, a pimple with a plug of pus develops.

Head gneiss (seborrheic eczema) is a harmless skin rash. It is caused by an overproduction of the sebum glands of the hairy scalp.

Neurodermatitis (atopic dermatitis, atopic eczema) leads to recurring skin inflammation with itching. The skin is extremely dry. In babies, neurodermatitis appears as a red itchy rash, especially on the face. The eczema spreads on the neck over the trunk and towards the diaper area. The backs of the arms and legs are also affected. In older children and adults, eczema can appear anywhere on the body. Very often the face – especially around the eyes and mouth – as well as the crook of the arm and the back of the knee are affected. But the upper part of the upper body and the neck can also be affected. The skin is dry, blotchy, reddish, and thickened.

Cradle cap in babies can be the precursor to neurodermatitis or a sign of an allergic predisposition.

Psoriasis is a chronic, inflammatory and recurring skin disease in which large amounts of scales form on the skin. The rash is noticeable by sharply defined, reddish and slightly raised spots. These are covered with silvery white scales. The spots can be small and dot-like, but they can also cover larger areas. Sometimes they can also itch. The superficial scales are easy to scrape off, while the deeper ones are more firmly attached to a young, thin layer of skin. If this layer of cuticles is also removed, small, punctiform skin bleeding occurs.

Lichen planus is a rare skin condition that causes intensely itchy, reddish nodules to form, usually on the insides of the wrists and ankles, lower legs . An autoimmune reaction is probably responsible.

Pityriasis rosea is an itchy rash that can spread from the trunk to the upper arms and thighs.

Rosacea (copper fin, acne rosacea) is an inflammation of the facial skin that is chronic and flares up. The disease can have different manifestations. Depending on the severity, there is persistent reddening with noticeably dilated veins (couperosis) on the face. Later, a skin rash with nodules and pus blisters can appear.

Other causes of rashes

A rash can also be a side effect of medication . Drugs that can trigger rashes are primarily antibiotics, non-steroidal anti-inflammatory drugs (NSAIDs – for example ASA, diclofenac, ibuprofen ), cortisone or certain high blood pressure, gout, cancer and diabetes drugs.

Herbal remedies can also trigger a skin rash: coriander oil, for example, can cause allergic reactions. The same applies to St. John’s wort products in combination with sunlight, as it can increase photosensitivity.

Lupus erythematosus is an autoimmune disease. A typical symptom is the butterfly-shaped rash on the left and right of the nose (butterfly erythema).

The psyche also plays a role in skin rashes, it is not for nothing that the popular saying goes: “The skin is the mirror of the soul”. For example, stress and psychological strain can trigger or worsen a skin rash.

If no cause can be found for the rash, doctors speak of an “idiopathic exanthema”.

Skin Rash: When Should You See a Doctor?

Often the rash is simply caused by using the wrong detergent or cream. It usually resolves when you avoid the substance. Even with infectious diseases, it often disappears on its own after a few days. However, you should see a doctor (GP, dermatologist, pediatrician) if:

  • you suddenly get a severe skin rash
  • You are unsure of the cause of the rash
  • the rash is extremely itchy, painful or swollen
  • the rash spreads to more and more parts of the body and does not go away
  • in addition to the skin rash, symptoms such as fever or shortness of breath
  • the rash develops in flares
  • the rash changes

You should always see a doctor with babies and children who have a rash.

Rash: what does the doctor do?

Important for the closer localization of the rash is the part of the body ( localization ) where the rash appears. For example, spots on the trunk, extremities, and face are often scarlet fever. Rashes on the face and neck are often caused by viral infections.

The doctor also checks whether the mucous membranes (mouth, genital area) are affected (for example in chickenpox and scarlet fever). Any accompanying symptoms, such as fever , cough , runny nose or itching, also play a role.

So doctors take a very close look at the rash. In addition to the localization, the  appearance (efflorescence) of the rash can also provide clues to the cause. A distinction is made between the following forms:

  • dots (maculae)
  • nodules (papules)
  • vesicles (vesicles)
  • Wheals (Urticae)
  • crusts
  • dry and wet districts

In the case of chickenpox, several different manifestations can also coexist at the same time. They can merge into each other.

The course of the skin rash over time also helps with the diagnosis: is it spreading? On which body regions? Is it relapsing? Does he change?

Additional tests are sometimes necessary for the diagnosis, for example a skin swab (detection of fungi), a tissue sample ( biopsy ), blood tests (viruses, bacteria) or an allergy test.

Rash: therapy

Therapy depends on the cause of the rash. In the case of a bacterial infection, for example, antibiotics are used. Antifungal agents ( antimycotics ) are used for fungal infections, and antivirals if necessary for viral infections.

You can also do something about the itching. Ointments and creams with antihistamines help here. Cortisone helps with allergies and skin diseases by having a strong anti-inflammatory effect and slowing down the immune system (immunosuppressive effect). Other immunosuppressants can also be useful in certain cases, for example in neurodermatitis. In addition, the doctor sometimes prescribes so-called immunomodulators (medicines that influence the immune system), for example for psoriasis.

Skin diseases are usually treated locally, i.e. with ointments, creams, tinctures or bath additives that contain certain active ingredients. Examples are ointments with urea (urea) or tar. In severe cases, the doctor sometimes also prescribes medicines for internal use, such as pills.

Rash: You can do this yourself

The best protection against a rash is healthy skin. And you can actively support the health of your skin so that it can keep pathogens in check:

Acidic pH: A healthy protective film on the skin is slightly acidic (pH 5.5) so that bacteria and fungi are effectively repelled. Basic body care products with a pH value above 7.0 (e.g. soap) destroy the protective acid layer on the skin and are therefore unfavourable. It is better to use products with a skin-neutral pH value (about 5.5).

The right skin cream : The drier the skin, the richer the care should be. Lotions with a lot of water are absorbed quickly, but can also dry out the skin. If your skin is brittle, you should therefore use greasy creams and ointments if possible. Exactly the opposite applies to weeping, open areas: light, water-based emulsions and lotions are ideal – they cool the skin and are easily absorbed by it.

Avoid allergy triggers : Always look at the list of ingredients for creams. Perfumes and preservatives can trigger an allergic reaction and increase the itching. The best thing to do is try out different body care products and see how your skin reacts.

No harsh substances : Keep harsh substances away from your skin. They are found, among other things, in washing lotions for the hands, but also in detergents, cleaning agents and detergents as well as chemical hair coloring products. It is best to wear protective gloves when handling such substances.

Save with the sun : Do not let too much sun on your skin, also because of the risk of sunburn and skin cancer. In combination with medicines or cosmetics, the sun’s UV light can also trigger allergic reactions.

Fresh air : The skin needs fresh air regularly. You should therefore prefer loose, breathable clothing, preferably made of cotton.

Keep nickel & Co. away from your skin : Do not wear nickel or other allergenic metals directly on your skin (e.g. in the form of chains or belt buckles).

Avoid extreme cold : It’s bad for the skin, it can dry it out and cause a rash . So put on several layers of clothing on top of each other in frosty temperatures in the “onion look”.

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