Definition
A pollen allergy is the hypersensitive reaction to components of different plant pollen. The pollen allergy is popularly called “hay fever“, in technical terms it is called “allergic rhinitis”. In most cases, the disease begins in early childhood and usually accompanies those affected throughout their lives.
It is assumed that the rate of illness is between 15% and 30% in children and adolescents. This means that almost every fifth child suffers from the pollen allergy. The therapy consists of avoiding the pollen, pharmacological allergens and a specific immunotherapy.
Causes
The direct cause of the symptoms of pollen allergy is the exaggerated immune reaction of the body to plant pollen. These pollen are harmless in themselves, so they do not normally pose a health risk to humans. In the case of an allergy, however, certain proteins in the plant pollen are (mis)recognized as pathogens.
This activates the immune system. The activation of the immune system leads to an inflammatory reaction. This occurs particularly at the places that have had contact with the allergen, i.e. the pollen.
The contact points are mainly the mucous membranes of the airways and the eyes. The messenger substances histamine and leukotrien play a major role in this process. The cause of the development of the allergy has not yet been sufficiently clarified.
The plant to develop an allergy is inheritable. In addition, it is assumed that too much hygiene in childhood is conducive to the development of an allergy. Especially city children, who are exposed to nature to a small extent, have a higher probability of developing a pollen allergy than country children. In addition, air pollution increases the allergic reaction of the body.
Associated symptoms
The classic symptoms of a pollen allergy are rhinitis, watery eyes and sneezing fits. Severe itching is also one of the main symptoms of hay fever. In principle, the symptoms are explained by the pathomechanism (active form of the disease) of the allergy.
Inflammatory reactions occur due to the increased release of messenger substances such as histamine, leukotrienes and prostaglandins from the mast cells. These are mainly localized in those parts of the body that have had contact with the pollen. One result of the inflammatory reaction is a dilatation of the blood vessels.
This causes the region to be supplied with more blood and appears reddish. The permeability of the blood vessels also increases. This leads to an increased leakage of fluid from the vessels.
This accumulation of fluid manifests itself in patients as swelling of the mucous membranes. The prostaglandins also cause the increased sensation of pain and itching. The symptoms are therefore mainly redness, swelling, increased pain perception and itching.
The itching often affects the throat and palate of the patient and can reach the ear. In the nose, this manifests itself as a so-called runny nose. This form of rhinitis is characterized by a strong discharge of secretions.
In addition, the airway in the nose is blocked by the swollen nasal mucous membranes and it is more difficult to breathe through the nose. In most cases there are also violent sneezing attacks, which can sometimes last for minutes. The bronchi and windpipe can also be affected by the allergy.
In some cases this can lead to coughing, in severe cases even to respiratory distress. If a whistling sound occurs during breathing at night, it is probably bronchial asthma. In many cases this is also caused by the allergy.
The allergic inflammatory reaction deprives the body of energy, as with other diseases. As a result, many affected people feel tired and exhausted. Sleep can be impaired by the pollen allergy, which increases the tiredness during the day and severely restricts the ill person in their daily life.
In addition to the airways, the eyes can also be affected by the allergic reaction. Here, for example, swelling of the eyelids occurs. This can lead to the eyes not being able to open as wide.
Rings under the eyes are a classic appearance of a pollen allergy in addition to the swollen eyelids. On the other hand, the eyes water very much, while nevertheless often a feeling of dry eyes develops.A foreign body sensation, which can occur, fits this. It is often reported about a feeling that feels like sand in the eye.
Vision problems can be particularly problematic. These occur rather rarely, but represent a considerable impairment in everyday life. In addition, the eyes can react more sensitively to light.
Because the conjunctiva of the eye is not protected by a mucous membrane (in contrast to the nose or the respiratory tract), irritation can often occur here. Conjunctivitis can also occur in some cases. However, unlike infectious conjunctivitis, allergic conjunctivitis is not contagious because it is not caused by bacteria.
For this reason, however, it can only be treated symptomatically; antibiotics do not help here. Conjunctivitis is characterized by itching and burning of the eyes. Redness and increased lacrimation are also part of the classic clinical picture of conjunctivitis.
Itching is a symptom that occurs in many clinical pictures, especially in inflammatory or allergic diseases. Itching is also one of the characteristic symptoms of a pollen allergy. The itching is triggered by messenger substances such as histamine.
The histamine is released more strongly as a result of the body’s allergic defence reaction and acts mainly at the point where the body came into contact with the allergen. In the case of pollen allergy, the eyes and respiratory tract are mainly affected. But also in the skin there is a strong release of histamine in an allergic reaction.
How exactly the histamine triggers the itching is not yet certain, but it is possible to combat the itching with the help of antihistamines (histamine receptor blockers). Red patches on the skin are also known as exanthema or rash. These exanthems can occur in the case of a pollen allergy and are often located in places that have had contact with the pollen.
Mostly the arms, legs and head are affected by the rash. These rashes manifest themselves as redness, sometimes there are also hives or blisters. The skin also feels warm.
The pollen can penetrate the skin via hair follicles or lesions and cause the allergic reaction. A systematic effect can also occur. In this case the body releases so much histamine that it is systematically distributed through the blood and can cause problems in other parts of the body.
For example, the intestines or even the skin are affected. In case of an allergic exanthema, the skin can be treated with antihistamines. In severe cases the administration of glucocorticoids (cortisone) is also conceivable.
