But it´s just a cold?! Far from it: pollen allergy is a chronic disease that should be taken seriously and treated. Here is an overview of symptoms, diagnostics, and therapy.
Watery eyes, constant sneezing, coughing or shortness of breath - the symptoms of pollen allergy are annoying and often limit the quality of life of those affected [1,2]. Unfortunately, hay fever season is no longer limited to the Spring and Summer months. The reason is climate change: the plant's leaves and buds sprout earlier, the pollen remains in the air longer and causes problems well into the Fall. .
What many don't know: Pollen allergy is a chronic respiratory disease that should be treated . If this does not happen, the allergy can worsen from year to year and even lead to asthma - both the pollen allergy and asthma will then persist for a lifetime . For those who seek treatment at an early stage, it is possible to test whether a special form of immunotherapy, known as hyposensitization, may be suitable. This can reduce the symptoms of pollen allergy and the risk of asthma .
But what exactly does a pollen allergy do to the body? How can it be recognized and treated? Can a pollen allergy be prevented? What is cross-sensitivity? We answer these questions in this article. You will also learn what influence the weather - for example, rain and thunderstorms - has on pollen and what you can do to relieve hay fever symptoms.
What is a pollen allergy?
In case of a pollen allergy, often also referred to as hay fever, the body experiences an allergic response to pollen produced by plants . Many plant species use pollen to spread their male genome. Heavy pollen grains can be transported by insects such as bees, light pollen grains spread with the wind, and thus ensure the survival of the plant species..
These so-called "wind-pollinated pollen" are only 10 to 20 micrometers in size and can easily be inhaled by humans. In the case of a pollen allergy, the normally harmless pollen triggers a violent allergic reaction in the body - especially in those parts of the body that come into contact with the pollen: nose, eyes, skin, and respiratory tract. Those affected suffer from swollen and irritated eyes, a cold, or a dry cough. These and other symptoms of hay fever are also known as "allergic rhinitis". .
By the way: The term "hay fever" originates from the observation that contact with hay causes symptoms in people with a grass pollen allergy - due to the pollen also present in hay. The word hay fever is also often used for allergies to pollen from early bloomers, such as birch, alder, or hazel .
Roughly 7.8% of people 18 and over in the U.S. have hay fever. .
What triggers a pollen allergy?
When inhaled, the plant pollen reaches the mucous membranes of the nose and lungs. The ingredients of the pollen, small protein components, are released on the mucous membranes. The proteins are harmless, but in case of a pollen allergy, they are classified as dangerous by the body. The immune system then develops special IgE antibodies tailored to the pollen proteins. The IgE antibodies bind to mast cells. The antibodies on these mast cells are now able to immediately recognize the allergen (i.e. the pollen proteins) upon renewed contact. This process is called sensitization .
The antibodies on the mast cells recognize the pollen proteins and bind them. The mast cells then release messenger substances. The messenger substance histamine triggers the typical symptoms of hay fever: sneezing, red, watery eyes, and coughing [10,14].
The pollen allergy is part of type 1 allergies, the so-called immediate type. This means that symptoms occur immediately after contact with the allergen. Symptoms can still occur up to six hours later .
By the way: Genes also play a role in pollen allergy! The more family members are affected, the higher the risk for children in this family to develop an allergic disease as well. For example, if both parents have the same allergy, 50 to 70 percent of the children will also develop one .
Pollen Allergy - Symptoms
The following symptoms often occur with a pollen allergy :
- runny or stuffy nose
- frequent sneezing, itchy nose
- watery, itchy, inflamed eyes
- skin reactions - especially in the face (welts, itching, swelling, eczema)
- exhaustion and fatigue
- headache, migraine
Some of those affected report light-sensitive eyes and a deteriorated sense of smell and taste . A pollen allergy may also lead to asthma. People with hay fever should pay attention to the following symptoms - they can be an indication that asthma is developing :
- Dry irritable cough (during physical exertion or outdoors)
- Burning sensation behind the sternum (when breathing in)
- For children: Decrease in sporting performance, physical condition
- Frequent infections of the lower airways (bronchitis)
Beware of cross-sensitivities!
Anyone suffering from a pollen allergy and those who also cannot tolerate certain foods may have developed a so-called "cross-sensitivity". This is due to the similar biochemical composition of pollen: The protein building blocks of birch pollen are so similar to those of apple pollen, for example, that the immune system in some cases regards both as identical and fights them equally. This cross-sensitivity is therefore also called "pollen-associated food allergy". .
In affected people, eating an apple can now trigger the so-called oral allergy syndrome (OAS). Swelling, itching, and tingling on the tongue and in the mouth and throat can occur. Swelling of the lips, tongue, or throat can even be life-threatening .
Studies show that 20 to 70 percent of those allergic to pollen develop symptoms of OAS after eating fresh fruit, raw vegetables, nuts, or certain herbs .
An overview of the most important cross-allergens can be found here :
The classic cross-allergens to birch pollen are:
The classic cross-allergens to ragweed pollen are:
- sunflower seeds,
The classic cross-allergens to grass and wheat pollen are:
Good to know: Most allergens in fruit and vegetables can be destroyed by heating - this means that the food is tolerated by allergy sufferers when steamed, grilled, or cooked. Caution: Celery, herbs, and spices can still cause discomfort even after cooking. !
Pollen: Varieties, Seasonal and Weather Dependence
Hay fever occurs mainly in spring and summer, the time when most plants are in bloom . However, each plant species has a different blooming period, which depends on the geographical location and weather conditions. Some trees such as hazel and alder, for example, bloom depending on temperature. The wide variety of climates in different parts of North America mean that different areas experience dramatically different pollen levels throughout the year. As an example of this, Seattle, WA is virtually pollen free in the depths of winter between late October and the end of December, while Waco, TX can experience a reasonably high pollen level year round .
Hay fever: When is pollen season?
The following is a summary of information about the plants whose pollen is particularly likely to trigger an allergy during the blooming period. The pollen comes from trees, grasses, and herbs [10,21].
|Rank||Common name(s)||% abundance||Pollen Season|
|1||Oak (Tree pollen)||19.6||Feb - Jun|
|2||Cypress, Juniper, Cedar (Tree pollen)||19.4||Year Round|
|3||Ragweed (Weed pollen)||7.2||July - December|
|4||Mulberry (Tree pollen)||6.7||Feb - July|
|5||Pine (Tree pollen)||4.5||Year Round|
|6||Elm (Tree pollen)||4.6||Year Round|
|7||Ash (Tree pollen)||3.7||Nov - May|
|8||Birch (Tree pollen)||3.8||Feb - Jun|
|9||Grass (Grass pollen)||3.7||Feb - Nov|
|10||Maple (Tree pollen)||3.7||Feb - July|
|11||Poplar, aspen, cottonwood (Tree pollen)||2.5||Feb - Jun|
Our tip: As mentioned above, the diverse climates of the United States makes if very tough to pinpoint "pollen season". Get a current report of the types and intensity of the plant allergens affecting your part of the country from pollen.com.
Pollen allergy and rain
To distribute their genetic material, the flowering plants release their pollen into the air. The light pollen can fly hundreds of kilometers. The windier it is, the more pollen is spread and the further it goes, too. . When it rains, however, allergy sufferers usually feel a sense of relief: the pollen sinks to the ground, so that the air is "cleaned" of pollen and causes fewer complaints for those affected. .
If a thunderstorm occurs during the pollen season, people with pollen allergy should be careful: During a thunderstorm, the allergic symptoms can increase significantly in the initial 20 to 30 minutes .
Before a storm, winds often occur. Based on studies, it is assumed that these winds collect large quantities of flower pollen from upper layers of air. Through strong down winds, the air masses with the pollen reach the bottom and reach the air we breathe .
During thunderstorm rain the pollen-releasing plants are buffeted by the rain, thus releasing many particles. The pollen particles are also broken down to a degree, becoming so small that they can penetrate deep into the lower respiratory tract, the bronchi . In people who are allergic to pollen, they can intensify asthma symptoms or even trigger them for the first time .
Recommendation: People with hay fever should stay inside buildings and keep windows and doors closed before and during a thunderstorm [24,25].
Pollen allergy diagnosis
Do you suspect that you might suffer from a pollen allergy? Below you can find some of the diagnostic possibilities.
Common examination methods used to collect evidence of allergies are skin and blood tests .
How the prick test works
The prick test is the standard test for suspected allergies of the immediate type (Type I), which also includes pollen allergy or hay fever.
The prick test is performed on the skin: Small drops of allergen solutions are applied to the skin - usually on the forearm or back. A needle is then used to prick the skin through the drop. A "positive", i.e. allergic reaction of the skin is evident within a few minutes by reddening and a welt (itchy, roundish skin elevation) around the prick site.
The size of these welts determines the extent of the reaction and the diameter is recorded on the test sheet. Welts with a diameter of three millimeters or more indicate an increased allergy susceptibility, also called a sensitivity. Please note: Only in case of associated symptoms do we also speak of an allergy !
How the IgE test works
A sensitivity to pollen can also be detected by measuring the IgE antibodies in the blood. Should your body react allergic to certain pollen, it releases IgE antibodies to switch off the allergens. The antibodies can be detected in blood serum and provide information about whether and which pollen allergy is present .
Just as with the prick test, experts only speak of an allergy if the test is positive and allergy symptoms occur at the same time.
The cerascreen® Pollen Allergy Test is also a blood test. This is a sampling and sending kit for home use. This means that you use the kit to take a small blood sample at home and send it to a specialist medical laboratory. The laboratory will analyze the concentration of IgE antibodies against 15 different pollen and the sap of the Ficus Benjamina.
The blood test has a major advantage: It can also be performed when a prick test is not possible. For example, if the skin is acutely irritated or you are taking medication that would suppress the body's immune response .
Diagnosis by a physician
Only physicians are permitted to provide a reliable diagnosis of hay fever. In addition to skin or blood tests, a thorough medical history must be taken. The following questions are important :
- Are there allergic illnesses in parents or siblings?
- In which months do the symptoms appear?
- How exactly do they manifest themselves?
Treatment of Pollen allergy
The treatment of hay fever depends on the symptoms and on how well the pollen allergen causing it can be avoided. Avoiding pollen is the most important measure to prevent symptoms - but in reality, this is difficult to achieve because the pollen is in the air we breathe. Other options include hyposensitization and taking medication. Here you will find an overview of all three methods:
Prevention: This is how you can avoid severe issues!
- Avoid blooming pastures and fields during the blooming phase. Go for walks especially after the rain, when the air is cleared of pollen - but be careful during thunderstorms!
- Only air out the house in the morning and evening, when there is less pollen in the air: the lowest pollen concentration and therefore the best time for airing is between 6.00 and 8.00 a.m. in the city, and between 7.00 and 12.00 p.m. in the country.
- Install pollen protection screens on the bedroom window - they keep out at least 85% of the pollen.
- Pollen tends to get caught in your hair and clothing. So, wash your hair in the evening and change your clothes before going to bed! Do not put blooming plants in the bedroom.
- Keep the windows closed when driving.
Are you planning your next vacation? Allergists recommend that people with hay fever spend time by the sea or in the mountains. The air there contains very little pollen and offers relief to those affected, especially during the main blooming period of the respective plant .
With hyposensitization, the body is first given a very low, then slowly increasing dose of pollen allergens, usually at intervals of several weeks. In this way, the body gradually becomes accustomed to the pollen over a longer period, so that the immune system is less likely to react to it .
Hyposensitization should begin three to four months before the start of the pollen season, otherwise, too many allergens could act on the body at the same time. During the pollen season, the treatment can then be continued in a reduced form or interrupted completely. Hyposensitization lasts about three years .
Studies suggest that hay fever hyposensitization may prevent the development of asthma in children . However, the child should be at least five to six years old .
Treatment with medication
If the symptoms are very severe during the pollen season or if, for example, the mucous membranes become inflamed, medication is recommended. This can have twofold benefit: first, the symptoms are improved - second, the risk of asthma can be reduced .
Cromones: They are the mildest form and are often prescribed to pregnant women. Cromones inhibit the release of histamine and thus prevent allergic inflammatory reactions. It is recommended to use them as a precautionary measure one week before the first pollen flight. Cromones are available as a nasal spray or eye drops .
Good to know: Medications only relieve symptoms, but do not eliminate the causes of the pollen allergy. .
Antihistamines: They block receptors for the inflammatory substance histamine quickly and effectively. This means that histamine is released, but other cells cannot perceive it. This slows down inflammatory processes and alleviates pollen allergy symptoms. Antihistamines are often available as nasal sprays. Those affected should take them regularly throughout the pollen season and not only when acute symptoms occur. .
Cortisone: Has an anti-inflammatory effect, relieves runny nose, and reduces swelling of the nasal mucous membranes. However, cortisone also has side effects: Nosebleeds, dry nose, and irritation of the throat may occur. Cortisone is available as a nasal spray. For severe allergic symptoms, pills or injections are also possible .
Can a pollen allergy be prevented?
According to current research, several factors contribute to the development of allergies: These include hereditary predisposition and various environmental factors which - if a predisposition exists - influence the development, severity, and course of the allergies .
It is also suspected that allergies develop in early childhood. Many expectant parents, therefore, wonder whether they can prevent their child from developing a pollen allergy. The good news is that there are several measures you can take during pregnancy, but also after the birth of your child, to reduce the risk of developing a pollen allergy .
Recommendations during pregnancy
- Eat a healthy and balanced diet. Do not follow certain restrictive diets, i.e.: do not avoid food allergens (e.g. milk protein, nuts, cereals, etc.) - unless there are disease-related reasons for this, such as gluten intolerance.
- Eat fatty ocean fish such as salmon, herring, or mackerel regularly. There are indications that the contained Omega-3-Fatty Acids can reduce the risk of allergy in a newborn.
Warning: Be aware that certain types of ocean fish, such as tuna, eel, and halibut, contain large amounts of the heavy metal mercury, which can impair the development of children.
Recommendations after birth
- Breastfeed your newborn, if possible, at least for the first four months.
- If one of the parents suffers from an allergy and you cannot breastfeed, you should give your newborn baby a special hydrolyzed formula. These products have the abbreviation HA (for hypo-allergenic) on the packaging. The milk powder consists of ingredients with low allergenicity.
- Eat fatty fish regularly even when breastfeeding.
- After the end of the first month of life, a supplementary diet should be introduced. Fish could reduce the risk of allergies. For this reason, give your child fatty fish regularly during the first year of life.
- Avoid excess weight/obesity in your child.
General lifestyle recommendations
- If you already have an allergy in your family and your child is therefore to an increased risk of allergies, it might be best not to own cats. According to current studies, keeping dogs is not associated with an increased risk of allergies.
- Do not use any special allergy products such as mite mattress protectors or similar if you do not suffer from such an allergy.
- Avoid an indoor climate that promotes mold growth. That means air out your home regularly!
- Cigarette smoke increases the risk of allergies! Avoid active and passive smoking during pregnancy and especially in the presence of your child.
- Your child should be exposed as little as possible to air pollutants such as car exhaust or volatile gases (produced, for example, during painting work).
At a glance: Pollen allergy
What is a pollen allergy and how is it triggered?
In the case of a pollen allergy (hay fever), the body reacts to plant pollen. The immune system forms antibodies (IgE antibodies) against pollen components (allergens) and thus tries to fend off the supposedly harmful substances. This leads to a so-called "sensitization". If there is renewed contact with the allergen, the immune system releases messenger substances that trigger allergic reactions.
What are the symptoms of a pollen allergy?
Those affected often suffer from an itchy, runny or stuffy nose with frequent sneezing. Your eyes may water, itch, or become inflamed. People who are allergic to pollen can also show skin reactions - often hives, itching, swelling, or eczema on the face. Hay fever can be accompanied by fatigue, headaches, or migraines. Some sufferers report light-sensitive eyes and a deteriorated sense of smell and taste. A pollen allergy can even lead to asthma.
When is the pollen season?
Each allergenic plant has a certain blooming period - during this period, symptoms occur. The plants bloom depending on the season, some also depending on the temperature. The blooming period is also influenced by the geographical location. Your local weather station is likely a good source for localized information regarding pollen levels.
What influence does the weather have?
When it rains, the pollen contained in the air sinks to the ground, so that the air is "cleaned" of pollen and causes fewer complaints for people with pollen allergies.
The opposite can be true during thunderstorms due to high wind and the breakdown of pollen into even smaller particles. The allergic symptoms can become more intense and even cause asthma! People with hay fever should stay inside buildings and keep windows and doors closed before and during a thunderstorm.
How can I find out if I am suffering from a pollen allergy?
Skin or blood tests are available for the diagnosis of a pollen allergy.
In the skin test or the so-called prick test, drops of allergen solutions are applied to the skin and introduced into the bloodstream through a needle stick. Redness and welts - i.e. the extent of the sensitization or allergic reaction - are documented.
The blood test: Sensitivity to pollen can also be detected by measuring the IgE antibodies in the blood. Should your body react allergic to certain pollen, it releases IgE antibodies to switch off the allergens. The antibodies can be detected in blood serum and provide information about whether and which pollen allergy is present.
How is a pollen allergy treated?
The treatment of hay fever depends on the severity of the symptoms and how well the pollen allergen that causes them can be avoided. Avoiding pollen is the most important measure to avoid symptoms. Other options include hyposensitization and taking medication.
Can a pollen allergy be avoided?
According to the current state of research, allergies usually develop in early childhood. There are various measures you can take during pregnancy, but also after the birth of your child, to ensure that the risk of developing a pollen allergy is reduced.
For example, it is recommended to eat a balanced diet rich in omega-3s during pregnancy and breastfeeding.
 J. Bousquet et al. a. , "Work productivity in rhinitis using cell phones: The MASK pilot study", Allergy , Vol. 72, No. 10, pp. 1475–1484, 2017, doi: 10.1111 / all.13177.
 J. Bousquet et al. a. , "The Allergic Rhinitis and its Impact on Asthma (ARIA) score of allergic rhinitis using mobile technology correlates with quality of life: The MASK study", Allergy , Vol. 73, No. 2, pp. 505-510, Feb. 2018 , doi: 10.1111 / all.13307.
 "Climate change and pollen allergies", Federal Ministry for the Environment, Nature Conservation and Nuclear Safety . https://www.bmu.de/themen/gesundheit-chemischem/gesundheit-und-umwelt/klimawandel-und-gesundheit/allergien/klimawandel-und-pollenallergien/ (accessed June 23, 2020).
 "WHO | Allergic rhinitis and sinusitis ”, WHO . https://www.who.int/respiratory/other/Rhinitis_sinusitis/en/ (accessed June 10, 2020).
 "Worse than many people know: hay fever", AEDA - Doctors' Association of German Allergologists https://www.aeda.de/presse/pressearchiv/einzelansicht/?tx_ttnews%5Btt_news%5D=234&cHash=0e0d9cc4ddcffa1bf00cccf13c92ef9d (accessed June 10d , 2020).
 C. Möller et al. a. , "Pollen immunotherapy reduces the development of asthma in children with seasonal rhinoconjunctivitis (the PAT study)", Journal of Allergy and Clinical Immunology , Vol. 109, No. 2, pp. 251-256, Feb. 2002, doi: 10.1067 / May.2002.121317.
 "Hay fever" What is hay fever? "Lungenaerzte-im-Netz", Deutsche Lungenstiftung eV and Association of Pneumological Clinics eV https://www.lungenaerzte-im-netz.de/krankheiten/heuschnupfen/was-ist-heuschnupfen/ (accessed June 09, 2020).
 "The Importance of Pollinators for Agriculture - Agricultural Productivity and Pollination Protection". Accessed June 09, 2020. [Online]. Available from: https://www.europeanlandowners.org/files/pdf/2014/Pollinators_DE_FIN2_LR.pdf.
 "Hay fever - Basics", Allergy Information Service - Helmholtz Center Munich - German Research Center for Health and Environment . https://www.allergieinformationsdienst.de/krankheitsbilder/heuschnupfen/grundlagen.html (accessed June 04, 2020).
 "ALLERGY STATISTICS", American Academy of Allergy, Asthma, & Immunology (AAAAI). https://www.aaaai.org/about-aaaai/newsroom/allergy-statistics (accessed October 05, 2020).
 U. Langen, R. Schmitz, and H. Steppuhn, “Frequency of allergic diseases in Germany”, May 2013, doi: http://dx.doi.org/10.25646/1404.
 "Lifetime prevalence of bronchial asthma, hay fever, neurodermatitis and contact eczema [keyword: pollen allergy]", federal health reporting - jointly supported by RKI and DESTATIS . http://www.gbe-bund.de/gbe10/results.prc_tab?fid=24207&suchstring=pollenallergie&query_id=&sprache=D&fund_typ=TAB& Methode=2&vt=1&verwandte=1&page_ret=0&seite=&p_lfd_nr=15&p_newsid=&phlsaid=15&p_newsid=&phls_nr=15&p_lfd_nr=15&p_newsid=&phls_aid=&p_lfd_nr=15&p_newsid=&phls_no=15&p_news9=&phls 3 & p_janein = J # SEARCH =% 2522pollenallergy% 2522 (accessed June 06, 2020).
 Robert Koch Institute, "Allergic diseases in children and adolescents in Germany - cross-sectional results from KiGGS Wave 2 and trends", 2018, doi: 10.17886 / RKI-GBE-2018-075.
 "Allergies | Symptoms, Diagnosis, Treatment & Management, " The American Academy of Allergy, Asthma & Immunology . https://www.aaaai.org/conditions-and-treatments/allergies (accessed June 04, 2020).
 "Hay fever» Risk factors »Lung doctors-on-the-net". https://www.lungenaerzte-im-netz.de/krankheiten/heuschnupfen/risikofaktoren/ (accessed June 22, 2020).
 "Hay fever - Symptoms", Allergy Information Service - Helmholtz Center Munich - German Research Center for Health and Environment . https://www.allergieinformationsdienst.de/krankheitsbilder/heuschnupfen/symptome.html (accessed June 10, 2020).
 "Heuschnupfen" disease picture "Lungenaerzte-im-Netz", German Lung Foundation eV and Association of Pneumological Clinics eV https://www.lungenaerzte-im-netz.de/krankheiten/heuschnupfen/krankheitsbild/ (accessed June 10, 2020) .
 "Allergy Center Charité | Patient information ", pollen-associated food allergy . https://www.allergie-centrum-charite.de/herzig-willkommen-zu-den-sprechstunden-br-des-allergie-centrum-charite/nahrmittelallergien/patienteninfo/ (accessed June 06, 2020).
 A. Price, S. Ramachandran, GP Smith, ML Stevenson, MK Pomeranz, and DE Cohen, "Oral Allergy Syndrome (Pollen-Food Allergy Syndrome)", Dermatitis , Vol. 26, No. 2, p. 78 -88, Apr. 2015, doi: 10.1097 / DER.0000000000000087.
 “Pollen Food Allergy Syndrome”, American College of Allergy, Asthma & Immunology (ACAAI), https://acaai.org/allergies/types/food-allergies/types-food-allergy/oral-allergy-syndrome (accessed October 5, 2020)
 Lo, F., Bitz, C.M., Battisti, D.S. et al. Pollen calendars and maps of allergenic pollen in North America. Aerobiologia 35, 613–633 (2019). https://doi.org/10.1007/s10453-019-09601-2
 "Weather and Climate - German Weather Service - Services - Pollen Risk Index". https://www.dwd.de/DE/leistungen/gefahrenindizespollen/gefahrenindexpollen.html (accessed June 04, 2020).
 "Thunderstorm Asthma", Allergy Information Service - Helmholtz Center Munich - German Research Center for Health and Environment . https://www.allergieinformationsdienst.de/aktuelles/schwerpunktthemen/gewitterasthma.html#c189998.
 G. D'Amato, G. Liccardi, and G. Frenguelli, “Thunderstorm-asthma and pollen allergy”, Allergy , Vol. 62, No. 1, pp. 11-16, 2007, doi: 10.1111 / j .1398-9995.2006.01271.x.
 M. Hew, M. Sutherland, F. Thien, and R. O'Hehir, "The Melbourne thunderstorm asthma event: can we avert another strike?", Internal Medicine Journal , Vol. 47, No. 5, p . 485–487, 2017, doi: 10.1111 / imj.13413.
 "Hay Fever Diagnosis", Allergy Information Service - Helmholtz Center Munich - German Research Center for Health and the Environment . https://www.allergieinformationsdienst.de/krankheitsbilder/heuschnupfen/diagnose.html (accessed June 11, 2020).
 "Skin tests for allergy diagnosis", Allergy Information Service - Helmholtz Center Munich - German Research Center for Health and Environment . https://www.allergieinformationsdienst.de/hauttests.html#c192934 (accessed June 11, 2020).
 "Laboratory tests for allergy diagnosis", Allergy Information Service - Helmholtz Center Munich - German Research Center for Health and Environment . https://www.allergieinformationsdienst.de/diagnose/labortests.html (accessed June 11, 2020).
 "Hay fever» Prevention »Lungenaerzte-im-Netz", Deutsche Lungenstiftung eV and Association of Pneumological Clinics eV https://www.lungenaerzte-im-netz.de/krankheiten/heuschnupfen/vorbeugung/ (accessed June 11, 2020) .
 “Hay fever in children | kindergesundheit-info.de “, BZgA - Federal Center for Health Education . https://www.kindergesundheit-info.de/themen/krankes-kind/ Krankungen/allergien/heuschnupfen/ (accessed June 11, 2020).
 "How is hay fever treated?", Allergy Information Service - Helmholtz Center Munich - German Research Center for Health and Environment . https://www.allergieinformationsdienst.de/krankheitsbilder/heuschnupfen/therapie.html#c191311 (accessed June 11, 2020).
 "Heuschnupfen» Therapy »Lungenaerzte-im-Netz", Deutsche Lungenstiftung eV and Association of Pneumological Clinics eV https://www.lungenaerzte-im-netz.de/krankheiten/heuschnupfen/therapie/ (accessed June 11, 2020) .
 “Risk and provocation factors for the development of allergies”, Allergy Information Service - Helmholtz Center Munich - German Research Center for Health and Environment . https://www.allergieinformationsdienst.de/immunsystem-allergie/risikofaktoren.html (accessed June 23, 2020).
 "S3 guideline allergy prevention - update 2014: guideline of the German Society for Allergology and Clinical Immunology (DGAKI) and the German Society for Child and Adolescent Medicine (DGKJ)". Accessed June 08, 2020. [Online]. Available at: https://www.awmf.org/uploads/tx_szleitlinien/061-016l_S3_Allergiepr%C3%A4vention_2014-07-abgelaufen.pdf.