skin rash

and Carola Felchner, science journalist Updated on

Ingrid Müller is a chemist and medical journalist. She was editor-in-chief of for twelve years. Since March 2014 she has been working as a freelance journalist and author for, among others, Focus Gesundheit, the health portal ellviva.de, the publishing house living crossmedia and the health channel of rtv.de.

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Carola Felchner is a freelance writer in the medical department and a certified training and nutrition advisor. She worked for various specialist magazines and online portals before becoming a freelance journalist in 2015. Before starting her internship, she studied translation and interpreting in Kempten and Munich.

More about the experts All content is checked by medical journalists.

A skin rash (exanthema) can suddenly appear on different parts of the body and look very different: For example, spots, blisters or scales can form on the skin. Infectious diseases such as chickenpox or measles can be behind the rash, but also allergies or various skin diseases - such as psoriasis or neurodermatitis. Learn what rash can mean and how to treat it.

Brief overview

• Description: reaction of the skin to external or internal influences; expresses himself inter alia. in itching, redness, blisters, nodules, oozing, etc.
• Causes: various, e.g. B. Infectious diseases (measles, scarlet fever, rubella, rubella, hand and foot disease, borreliosis, 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: if the rash is severe, changes, the cause is unclear, extremely itchy or painful, spreads, additional discomfort occurs
• 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 .; mostly local treatment with ointments or creams

Rash: Description

The 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.

The skin usually reacts immediately and clearly visibly 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". The skin changes can in principle affect the whole body, but can also be limited to individual areas, in which case experts also speak of a rash. Some people have a rash on their face, others on their fingers, hands, knees, legs, feet, toes, elbows, forearms, stomach or back. The mucous membrane in the mouth and throat or the skin on the genital organs can also be affected.

For example, the rash can consist of colored spots, fluid-filled blisters, pustules, wheals, or nodules. Dermatologists can often determine the cause by looking at the appearance of the rash. Itching is a very common symptom of skin rashes. However, the rash may burn or cause pain or a feeling of warmth.

Eczema also manifests itself in skin rashes, but they are always based on skin inflammation. Specifically, "eczema" is a collective term for inflammatory skin diseases that are not contagious. Basically, external or internal factors can cause eczema.

Rash: causes and possible diseases

Skin rashes can have very 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 an infectious disease caused by viruses. In addition to the high fever, a fine, red, itchy rash develops on the chest, stomach and back. It can spread to the arms and legs, but disappears after a few days.

Scarlet fever (Scarlatina) is a typical childhood disease caused by an infection with bacteria (streptococci). The rash caused by the toxins of the bacteria is typical, among other things. It begins with small redness in the folds 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 as well as the palms of the hands and soles of the feet remain free of rashes. In some patients, the rash is absent or weak. After about a week, at the latest after three, the rash disappears completely.

Measles is another childhood illness caused by viruses. It is highly contagious and is spreading 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 bleeding from the skin may occur. The rash will go away after about five days.

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

Rubella (erythema infectiosum) is an infectious disease caused by the parvovirus B19. The butterfly-shaped rash is characteristic here, but it does not develop in all sufferers. The rash first forms 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 strength. The rash can recur within seven weeks.

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

With Pfeiffer's glandular fever, a rash can sometimes develop. However, this can also develop if the disease is treated with antibiotics, for example with ampicillin or amoxicillin. One then speaks of a drug eruption.

Borreliosis is an infectious disease that is usually transmitted by ticks. Lyme borreliosis is triggered by screw-shaped bacteria, so-called Borrelia. After a few days, a red spot can appear around the puncture site, which gradually enlarges and is usually pale in color in the middle. Doctors refer to this as "wandering redness" or erythema migrans.

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

The mucous membranes (mouth, conjunctiva, genitals) can also be affected. The red spots turn into fluid-filled, severely itchy blisters that gradually crust over. The rash runs in episodes, so that new red spots are added to the already existing skin vesicles and crusts every day. A so-called "starry sky" forms: a colorful picture of spots, papules, vesicles and crusts that eventually fall off. The vesicles on the mucous membranes 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 first time the herpes virus causes chickenpox, it persists in the body after the disease has subsided and can still become active again after years: in the form of shingles. The typical rash consists of blisters on a swollen, reddened surface.

The rash usually runs in a belt-shaped manner on the torso and extends, for example, from the back towards the sternum. But it can also cause a rash on the face and ears. After two to seven days, the blisters burst, creating small wounds that are gradually covered with scabs. After two to three weeks, the scab usually falls off.

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

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

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

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

Scabies is caused by mites, which cause a very itchy rash.

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

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

Typhus (typhus) is caused by the bacterium Rickettsia prowazekii, which is transmitted by clothes lice. After a few days, a blotchy rash forms, which begins on the trunk and quickly spreads to the arms and legs - but the head, neck, palms and feet remain without rash.

Typhoid is a serious diarrhea caused by bacteria (salmonella). Here, too, pinhead-sized, reddish spots can form on the stomach, chest and back, but they are not itchy.

A red chalk-like, itchy rash can also occur temporarily with dengue fever. The cause of this tropical disease is the dengue virus.

Allergies

An allergy is a hypersensitivity 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. Redness and itchy rashes 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 delimited itchy redness and swelling develop after a few hours. Depending on the severity, water bubbles, weeping areas, flakes and skin crusts appear.

The allergenic substances can have a direct external effect on the skin (such as UV radiation, cold). However, they can also have an irritating effect on the skin from the inside when they are inhaled or ingested with food. This is the case, for example, with hay fever and food allergies such as nut allergies.Medicines 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 allergenic object or material. Often these are fragrances or metals such as nickel. Even the smallest amounts are often enough to cause an allergic reaction. The skin then itches, swells, wets or reddens. The skin rash (eczema) usually forms on the area that was in contact with the allergy trigger (contact eczema). In particular, allergies to fragrances are on the rise. The symptoms: rough, reddened or flaky skin and itching. If the allergen acts on the skin for a long time, blisters, nodules and painful tears can occur.

Hives (hives, urticaria) are also an allergic disease. The rash here consists of red bumps. They look like mosquito bites or after coming into contact with nettles (hence hives).

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

Sunlight can also cause severe allergic skin reactions. There is excruciating itching, blisters or wheals (sun allergy). This is often done in combination with cosmetics such as skin and sun cream or perfume. Polymorphic light dermatosis (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, and extensor sides of the arms and legs. The PLD usually manifests itself with wheals, itchy spots or blisters.

In Mallorca acne, aggressive substances that are formed by UV light react with ingredients from sun protection and personal care products or the body's own sebum. An inflammatory reaction develops in the hair follicles. This results in acne-like pimples on the skin - mostly in the cleavage.

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

Sunburn is also one of the rashes.

Skin diseases

A rash can also be due to various skin diseases that are not contagious. Examples:

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

Head gneiss (seborrheic eczema) is a harmless 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, atopic dermatitis manifests itself as a red, itchy rash, especially on the face. The eczema spreads on the neck over the torso and towards the diaper area. The backs of the arms and legs are also affected. In older children and adults, eczema can appear all over the body. Very often the face - especially around the eyes and mouth - as well as the crooks of the arms and the hollows of the knees 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 eczema or a sign of an allergic disposition.

Psoriasis is a chronic inflammatory and recurring skin disease in which large amounts of scales form on the skin. The rash is noticeable as sharply demarcated, reddish and slightly raised spots. These are covered with silvery-white scales. The spots can be small and punctiform, but they can also cover larger areas. Some of them can also be itchy. The superficial scales can be easily scraped off, while the deeper ones sit more firmly on a young, thin layer of skin. If you also remove this cuticle, small, punctiform skin bleeding occurs.

Lichen planus (lichen planus) is a rare skin disease in which itchy, reddish nodules form, mostly on the inside of the wrist and ankles, and lower legs. Presumably an autoimmune reaction is responsible.

In pityriasis rosea, an itchy rash forms that can extend from the trunk to the upper arms and thighs.

Rosacea (copper fin, acne rosacea) is inflammation of the skin of the face that is chronic and progressive. The disease can be different. Depending on the severity, a persistent reddening with noticeably enlarged veins (couperose) appears on the face. Later, a skin rash with nodules and pus vesicles may appear.

Other causes of exanthema

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

Herbal remedies can also cause a rash: Coriander oil, for example, can cause allergic reactions. The same goes for 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 it is said in the vernacular: "The skin is the mirror of the soul". For example, stress and psychological distress can trigger or worsen a rash.

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

Rash: When Should You See a Doctor?

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

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

With babies and children who have rashes, you should always see a doctor.

Rash: what does the doctor do?

The part of the body (localization) where the rash occurs is important for narrowing down the rash. For example, spots on the torso, extremities, and face are often scarlet fever. Virus infections are often the cause of rashes on the face and neck.

The Azrt also checks whether the mucous membranes (mouth, genital area) are affected (for example in the case of 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 provide clues as to the cause. A distinction is made between the following forms:

• Dots (macules)
• Nodules (papules)
• Vesicles
• Wheals (Urticae)
• Crusts
• dry and weeping districts

With chickenpox, several different manifestations can coexist at the same time. They can merge into one another.

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

For the diagnosis, further examinations are sometimes necessary, for example a skin swab (detection of fungi), a tissue removal (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. In the case of fungal infections, antifungal agents (antimycotics) are used; in the case of a virus infection, antivirals may be used.

There is also something that can be done about the itching. This is where ointments and creams with antihistamines help. 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 with neurodermatitis. In addition, the doctor sometimes prescribes so-called immunomodulators (drugs that affect 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 prescribes medication for internal use, such as tablets.

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 at bay:

Acid pH: A healthy protective film on the skin is slightly acidic (pH value of 5.5), so that bacteria and fungi are effectively warded off. Alkaline body care products with a pH value above 7.0 (e.g. soap) destroy the protective acid mantle of the skin and are therefore unfavorable. It is better to use products with a skin-neutral pH value (around 5.5).

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

Avoid allergy triggers: Always look at the list of ingredients for creams. Perfumes and preservatives can trigger an allergic reaction and thus increase itching. It's best to try different personal care products and see how your skin reacts.

No aggressive substances: Keep aggressive substances away from your skin. They can be found in washing lotions for the hands, but also in dishwashing 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 on a regular basis. You should therefore prefer loose, breathable clothing, preferably made of cotton.

Nickel & Co. away from the skin: Do not wear nickel and other allergy-causing metals directly on the skin (e.g. in the form of chains or belt buckles).

Avoid extreme cold: it is bad for your skin and can dry it out and cause a rash. So put on several layers of clothing in an "onion look" when it is frosty.

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