Allergy | Skin rash on upper body

Allergy

In the case of an allergy, a skin rash is a classic symptom. Here the body reacts to a specific substance, which actually does not pose a threat. This substance is then called allergen.

The allergen leads to an inflammatory reaction of the mucous membranes and the skin. This inflammatory reaction is triggered by the fact that the body’s immune reaction releases a lot of histamine (a messenger substance) from mast cells (immune cells). This histamine causes the skin to redden and swell.

An increased perception of pain and itching are also caused by the histamine. In principle, allergic skin rashes can occur all over the body. They occur on the upper body if there was contact between the skin and the allergen.

Diagnosis

The skin rash is a diagnosis of the gaze. This means that just by looking at it one can make the diagnosis, since exanthema is usually easy to recognize. In addition, the anamnesis (asking for important information) is of great importance.

Symptoms like itching or pain must always be asked. Here the doctor can also determine whether a particular cause is related to the rash. For example, the use of certain drugs or the consumption of special foods can cause the rash. Other symptoms such as fever or general well-being are also important for a diagnosis.

Associated symptoms

On the one hand, the rash causes reddening of the skin. This can occur in different forms. Primary efflorescences can occur in the form of spots, blisters, pustules, wheals or papules (nodules).

However, it can be difficult for a person without dermatological experience to distinguish between these. In the course of secondary efflorescence, crusts, scales, ulcers or scars often appear. The shape of the rash often suggests a cause.

The rash may be accompanied by other symptoms. For example, fever, increased sweating, nausea or dizziness may occur. Breathing problems, coughing and swollen mucous membranes are also sometimes observed.

Skin rash with itching

Itching is a common accompanying symptom of the rash. It is an urge to scratch or rub your skin.Scratching and rubbing the skin often leads to a worsening of the rash, as the already irritated skin is additionally stressed by mechanical action. The itching is mainly caused by the messenger substances histamine and prostaglandin.

These are released from mast cells during inflammatory reactions. Typical skin diseases that trigger itching are e.g. the infectious diseases rubella, chickenpox and scarlet fever, which can also cause skin rashes on the upper body. However, these infections usually occur in childhood and can be distinguished by the form of the rash.

Psoriasis also leads to itchy skin rashes, which can occur on the upper body. White skin scales are usually visible here. Neurodermatitis also has a very itchy character, but is more likely to occur in the crook of the arm, the back of the knee and the face.