Over the years, researchers have observed that the pollen season has shifted forward by several days and continues on a bit longer in the autumn. If the climate is mild, the last grass or weed pollens can still be airborne in November, while the first hazel pollens appear as early as December. In this context, it would not make sense to refer to early summer hay fever (which it was originally called because it was assumed to be linked to hay and grass).
The effects of pollen allergy are underestimated. Sneezing, runny nose and itchy eyes are not the only symptoms that patients suffer from. During pollen season, many people cannot work to their full capacity; they sleep poorly and are exhausted. After several years, some allergy sufferers also develop what is known as the allergic march (moving from the upper respiratory tract to the lower). When this happens, hypersensitive reactions begin to occur in the bronchia, resulting in bronchial asthma.
Around 12 million people in Germany suffer from hay fever (14.8 per cent). Scientists at the Robert Koch Institute have arrived at this estimate through an analysis of 8,000 physician interviews.
Hay fever typically appears before age 25, usually in children between eight and 16 years of age. These days, more and more people over 50 are developing pollen allergies for the first time.
The allergy is caused by pollen, often from wind-pollinated plants. Pollen consists of individual pollen grains that contain the male gamete. Insect-pollinated plants produce less pollen than wind-pollinated plants, which need to release a lot of pollen in order to ensure pollination. This lightweight dust can travel hundreds of kilometres. The windier it is, the more widely the pollen is spread, and the higher the concentration. Rain drives pollen towards the ground, which then causes fewer symptoms (although storms can make symptoms worse). In some people, it takes only a few pollen grains to trigger a severe allergic reaction. For example, six rye pollen grains per cubic metre of air are enough to provoke an allergic reaction in people who are sensitised. (For comparison, a single ear of rye produces several million pollen grains.)
The main allergy triggering pollens come from trees, grasses and weeds.
- Trees: The pollen of early flowering species such as birch, hazel, alder and ash are particularly allergenic. Birch pollen allergy is especially common.
- Grasses: The Poaceae, commonly called ‘grasses’, are mainly responsible for triggering grass pollen allergies.
- Weeds: Mugwort and ragweed are highly allergenic.
Pollen contains water-soluble proteins that are released when they come into contact with the mucosa. In allergic individuals, the immune system generates IgE antibodies in reaction to the proteins, which are actually harmless. These antibodies bind to the body’s defence cells, known as mast cells, which then release anti-inflammatory substances such as histamine.
Histamine and other messenger substances stimulate the glands to release secretions and irritate the nerves, causing itching, sneezing and vasodilation that leads to redness and swelling of the mucous membranes.
Symptoms occur mostly in the areas that come into direct contact with the pollen allergens: the mucous membranes of the nose, eyes and mouth. These symptoms may include:
- Nose: runny nose with watery mucous, nasal congestion, itchy nose, sneezing
- Eyes: conjunctival redness, itching, tearing
- Mouth/throat: burning, itching
- Ears: itchy ear canals
- Lungs: dry cough (especially at night), wheezing, difficulty breathing (asthma)
- Skin: worsening of atopic dermatitis, in rare cases hives, redness
- General symptoms: fatigue, disrupted sleep, headache
People who are allergic to pollen allergy are often also allergic to certain foods. For example, raw apples or hazelnuts may trigger itching in the throat or swelling in the mouth in someone who is allergic to birch pollen. This is referred to as pollen food syndrome, which can develop because the proteins in some foods are similar to certain pollen proteins. In people with hay fever, the sensitised immune system perceives not only the pollen but also certain fruits, vegetables, nuts or spices as a threat and triggers an allergic reaction. For more information about this cross-reaction to food, please go to Celery, Cherry & Co.
As a first step in diagnosing hay fever, the doctor asks the patient about his or her symptoms. The questions include where the symptoms occur, at what time of day and during which seasons, how long they last and whether there are any allergic diseases in the family. After a physical examination, skin and/or blood tests are conducted in order to confirm the presence of an allergy. These tests reveal an allergic disposition to certain pollen allergens but do not provide evidence of an actual allergy. This is why a provocation test may be necessary if there are any doubts. For this test, small amounts of the suspected pollen allergen are applied to the patient’s nasal mucosa (or more rarely to the conjunctiva) under medical supervision. The patient is then observed for swelling of the nose, sneezing or watery eyes. A pulmonary function test is conducted if the patient suffers from respiratory symptoms. For this test, the doctor measures the amount of air that the patient inhales and exhales, and the speed at which air is exhaled. Changes to the airways can be determined through the results.
Incidentally, house dust mites, animal hair and mould can also cause symptoms that are similar to those of hay fever. For this reason, allergies to these substances should be ruled out.
Rhinitis caused by bacteria or viruses can also be mistaken for hay fever at first. However, a cold only lasts around ten days. It does not cause itching of the eyes, and the nasal mucous may become greenish yellow and viscous, whereas in hay fever it remains watery. Fever or swollen lymph nodes in the throat are also signs of a cold.
The most important measure in treating an allergy is to avoid the allergen. This can only be achieved to a certain degree for hay fever, but there are a few tricks that can help. In addition, various medications are available for symptomatic relief; however, they are not a cure for the allergy. Certain non-medicinal measures may also be helpful. One option that does treat the cause of hay fever is specific immunotherapy (also called hyposensitisation or desensitisation).
The drugs of choice are cortisone sprays and the newer antihistamines. For milder symptoms, chromones can be used in the form of eye drops and nasal sprays. Symptoms such as occasional sneezing, itchy eyes and runny nose can be relieved with antihistamines in the form of eye drops, nasal sprays or tablets. For more severe symptoms, corticosteroid nasal sprays are recommended (in combination with the newer antihistamines, if necessary). Eye and nasal sprays without preservatives should be used, since preservatives can also trigger allergic reactions.
Chromones (cromoglicic acid):
These substances prevent the mast cells from releasing the messenger molecule histamine, thereby reducing inflammation. However, they do not work immediately and are therefore used as a preventive measure. Their effect (especially on nasal symptoms) is rather weak, but they are well tolerated. Irritation of the nasal mucosa is a potential side effect.
These block the docking sites of histamine in the body, thereby reducing the allergic reaction. The substances work relatively quickly (tablets within an hour, nasal sprays within 15 minutes) and can therefore be used for acute symptoms. First-generation antihistamines also affect the central nervous system and can lead to fatigue and drowsiness. This particular effect is much lower in the newer antihistamines, which have a better side effect profile and cause fatigue and headache less often than the older medications.
Corticosteroid nasal sprays have an anti-inflammatory effect and can relieve symptoms such as runny or congested nose. They usually only begin to work after 12 to 24 hours and reach their full effectiveness after three to seven days. Modern corticosteroid nasal sprays have no systemic side effects, which means there are no side effects in the rest of the body. Unwanted side effects such as dry nose, nosebleeds or headaches may occur. A risk of delayed growth in children and adolescents has also been documented (for the medication beclometasone dipropionate). Even though this is considered unlikely, long-term use should be regularly monitored by a doctor.
Nasal sprays or drops containing this ingredient work by constricting the blood vessels in the nasal mucosa, which reduces swelling. However, they should only be used to treat nasal symptoms caused by colds. The maximum period of use is one week, since prolonged use may result in dependence on the medication and lead to rebound congestion once it is discontinued.
These substances inhibit the effect of leukotrienes which, like histamine, are messenger molecules that play a key role in (allergic) inflammation. Leukotriene antagonists are used to treat asthma. Since they are also effective in treating allergic rhinitis (but less effective than antihistamine tablets), they are a second-line drug for patients suffering from both asthma and hay fever. Potential side effects include headaches, gastrointestinal disorders and respiratory infections.
One form of therapy that treats the cause of hay fever is allergen specific immunotherapy (SIT). The goal of SIT is to allow the immune system to become used to the allergy-triggering pollen over time. First the pollen allergens that are causing the symptoms in the patient must be identified. One or two corresponding extract preparations are then selected. The preparation is injected once a week in increasing doses into the patient’s upper arm in the layer of fat under the skin (subcutaneous immunotherapy or SCIT). The highest dose is reached after one to three months, after which the injection is only administered once a month. This therapy takes around three to five years to complete and therefore requires persistence and cooperation from the patient. There is no guarantee that the allergy will ‘disappear’ once the treatment is completed. But studies show that a full course of SCIT can reduce symptoms and the need for medication over the long term by 60 to 80%. Furthermore, this treatment also reduces the risk of an allergic march and can therefore prevent asthma. It also reduces the probability that the patient will react to new, additional allergens.
Immunotherapy for hay fever can be an option for patients with symptoms that are severe and have persisted for over two years. Young people who do not react to many different allergens have the best chances of success.
Besides SCIT, another option is to administer the allergens as tablets or drops. The doses are given to the patient under the tongue (sublingual immunotherapy or SLIT). If using drops, these are applied under the tongue, where they are held for a moment and then swallowed. If using orally disintegrating tablets, these are placed under the tongue. The treatment has been proven effective specifically for grass pollen allergies. The advantage is that it can be carried out daily at home, although SLIT also takes at least three years to complete.
There is no conclusive evidence as to whether these two therapies are equally effective. The results of comparative studies indicate that specific immunotherapy using injections (SCIT) reduces symptoms somewhat more effectively than tablets or drops (SLIT). However, since SCIT and SLIT are similarly effective, patients can discuss which therapy to follow with an allergist.
Some doctors use homeopathy or acupuncture to reduce hay fever symptoms. However, there are no clear findings on the effectiveness of these therapies, since there are not enough conclusive studies available.
Prof. Dr. med. Dr. h.c. T. Zuberbier
Last changes made: July 2016