Causes/forms
Skin rashes (exanthema) occur in characteristic chronology. First there is a beginning of the skin change, then a climax, whose period of time can vary and finally healing. The cause of a skin rash is the so-called intolerance reaction of the skin cells in connection with the cells of the vessels.
The interaction of both cell types finally causes a rash. However, the exanthema reaction usually starts at the skin cells. The vessel sections belonging to the corresponding skin section then determine the type and severity of the triggered skin reaction.
The different triggers
In principle, a distinction is made between the triggers of skin rashes: These rashes are skin reactions which are mostly caused by skin cream applied to the skin or toxic substances. The substance is absorbed into the upper layer of the skin at different speeds. This usually does not yet lead to a rash.
Only when the toxic substance is removed via the bloodstream does the actual skin reaction occur. In this form of skin rash, a corresponding immunological reaction occurs after a certain substance has been applied to the skin. This reaction is mediated by the substance histamine.
The more histamine is released into the bloodstream, the stronger is usually the subsequent skin reaction. Triggers can also be various skin creams and cosmetics, but also numerous plant substances and flowers that touch and graze the skin. A histamine-mediated allergic reaction is triggered, for example, by touching the nettle.
After contact, a burning sensation occurs and after histamine is released into the bloodstream, the skin surface swells. Onions and similar herbal products can also cause a skin rash under certain circumstances.
- Toxic reactions
- Allergic reactions
- Infectious reactions
- Cancer diseases
Numerous childhood diseases trigger skin rashes.
The classic appearance, the place of spread and the time limit often give a quick indication of the type of disease. Typical diseases in which a skin rash occurs are More about the risk of infection: Is my rash contagious? Furthermore, a classification of the rash according to its shape can be made.
A distinction is made between Very often, drugs cause a rash on the skin. In most cases, the skin changes caused by this are extensive, not raised and itchy. They can occur on any part of the body.
However, arms, legs and trunk or back are most commonly affected. Triggering drugs can be: Ampicilins, sulfonamides, penicilins, cephalosporins, salicylates, ACE inhibitors, carbamazepine, phenytoin and allopurinol. However, if it does occur, it is usually a concomitant symptom of a weakened immune system of the entire organism, but not a cancer of the skin.
In this context, the cutaneous T-cell lymphoma should be mentioned, which is actually easily confused with a skin rash. The most common T-cell lymphoma is mycosis fungoides, which takes its name from the former confusion with a fungal disease of the skin (mycosis).
- Measles (in the prodromal stage so-called Kolping spots and exanthema in the oral mucosa, in the subsequent exanthema stage, after three days with a sharp rise in fever, a measles exanthema develops, which starts behind the ears and then spreads over the neck, face, shoulders and trunk.
In the convalescence stage, as the symptoms subside, scaling of the skin in the area of the exanthema may occur).
- Scarlet fever (1-2 days after the onset of fever, a fleeting rash usually develops on the inner side of the thigh. The onset is fast and occurs without a prodromal stage. Furthermore, there is an exanthema of the soft palate and whitish coating of the tongue).
For more information: Skin rash due to streptococci
- Rubella (after the appropriate prodromal stage, a rash appears first on the face and then on the entire body);
- Ring rubella (butterfly-shaped rash appears on the face with so-called perioral paleness, i.e. the mouth area is left out).
- Macular rash (not raised, skin change in skin level)
- Urticarial skin rash (slightly raised, flat, rounded, reddish)
- Vesicular rash (filled skin structures that can empty under pressure)
- Pustular skin rash (pimple-like skin changes)
- Infectious allergic skin rashes,
- Skin rashes toxic to infections (scarlet fever),
- Viral skin rashes (measles, varicella, rubella) and
- Bacterial rashes are differentiated (luetic exanthema).
An allergy is often manifested by symptoms such as swollen eyes, itching, chronic gastrointestinal complaints and skin rash. Allergies are hypersensitivity reactions of the body’s own defense system to actually harmless substances such as pollen or animal hair. The fact that these so-called allergens cause a strong reaction of the immune system is also used in the diagnosis of allergies.
A skin test (prick test), in which allergen extracts are brought into contact with the skin, shows by means of a local reaction of the skin (i.e. a skin rash) whether the person affected reacts hypersensitively to this allergen. The most common skin rash in allergies is the so-called hives (urticaria). The skin is initially pale red to red and resembles mosquito bites.
These skin changes usually become larger and form wheals (fluid-filled blisters) and itch strongly. This reaction is similar to the contact of the skin with nettles (Urtica). This rash can be localized at a specific location or can travel over the body.
It usually disappears after three to four hours, and after twelve hours at the latest, the rash is usually no longer visible on the skin. Another rash is allergic contact dermatitis. This rash is a delayed reaction to a contact substance, which in itself is not dangerous for the organism.
A contact substance on which allergic contact eczema frequently develops is, for example, nickel or latex. Intolerances to certain foods can also become apparent through skin rashes. Food allergies often cause reactions of the mucous membranes, but can also lead to skin rashes with itching.
Peanut allergy is particularly serious, as it can often lead to severe allergic reactions, up to the life-threatening condition of anaphylactic shock. Insect bite allergies also typically manifest themselves in skin lesions. For example, extensive, swollen and reddened skin reactions often occur when there is hypersensitivity to insect venoms. To prevent rashes in allergies, antihistamines or cortisone can be taken, as these drugs suppress the symptoms. If allergic rashes occur and the cause cannot be determined, the person affected should be examined for diseases such as immune disorders or other allergy-like conditions.
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