Hay fever symptoms: How do they develop?
With hay fever, the body reacts allergically to protein components of plant pollen in the ambient air (aeroallergens). Where the body comes into contact with this pollen (mucous membranes in the nose, eyes and throat), the typical hay fever symptoms appear.
The pollen proteins cause the body to release inflammatory messengers (such as histamine): These dilate the blood vessels, causing the nasal mucosa to swell. The inflammatory messengers also attract cells of the immune system, which trigger an inflammatory reaction in the mucous membranes.
These processes then manifest themselves in typical hay fever symptoms, for example
- itchy, blocked or runny nose
- conjunctivitis with itchy, reddened and watery eyes
- swollen eyelids
- possibly also itching of the mucous membranes in the mouth and throat
- Impairment of sleep at night and therefore severe tiredness during the day
- Feeling ill with aching limbs and fatigue (similar to a cold)
Pollen allergy symptoms occur as soon as and as long as the plants in question release their pollen into the air. In mild winters, alder and hazel, for example, can start to bloom early. People who are allergic to these plants may therefore experience symptoms as early as December or January.
Cross allergy
In some people, hay fever symptoms are accompanied by an intolerance to certain foods. The cause of this is a so-called cross-allergy. The body not only reacts allergically to the proteins in plant pollen, but also to similar proteins in food.
For example, most birch pollen allergy sufferers cannot tolerate raw apples, hazelnuts or cherries. When such foods are eaten, the body of those affected reacts in a similar way as if pollen had “invaded” it:
In some cases, a cross-allergy only occurs temporarily, for example during stressful phases of life.
You can read more about cross-reactions in allergy sufferers in the article Cross-allergy.
Overview of important cross-allergies:
|
Pollen type |
Possible cross-allergens in these foods |
|
Tree pollen (such as birch, alder, hazel) |
(raw) apple, apricot, fig, cherry, kiwi, nectarine, peach, plum, carrot, (raw) potato, celery, soy, hazelnut |
|
Mugwort |
Spices (such as anise, paprika), carrot, mango, celery, sunflower seeds |
|
Ragweed (ragweed) |
Banana, cucumber, melon, zucchini |
|
Grass and cereal pollen |
Flour, bran, tomatoes, vegetables |
Allergic asthma
The allergic reaction to the pollen causes the immune system to overreact in the bronchial tubes. These cramp up (bronchoconstriction) and form a viscous secretion. This makes it particularly difficult for those affected to breathe out.
Allergic asthma is a serious illness. Precisely because the connection between hay fever and asthma is becoming more and more obvious through research, hay fever symptoms should not be ignored – they can be a preliminary stage of asthma, so to speak. It therefore makes double sense to have pollen allergy symptoms treated:
You can read more about the treatment options for hay fever in the article Hay fever – therapy.
