What is hay fever?
Hay fever, also known as allergic rhinitis, is an allergic hypersensitivity reaction occurring in the nasal mucosa and in the conjunctiva of your eyes. It is estimated to affect around 1 in 5 people in the UK and in Europe, particularly those who suffer from asthma and eczema. People suffering from hay fever experience symptoms such as sneezing, itching, rhinorrhea, and nasal congestion often following exposure of aeroallergens. The allergy is caused by inhaling plant pollens which release a chemical called histamine, causing inflammation. The pollen comes from various species of trees, grass, weed and plants. Therefore, the allergy symptoms can vary depending on the season in which the plants are blossoming. For example, people who are allergic to tree pollens usually have symptoms from March to May, while people allergic to grass pollens have symptoms from June to July. There is also a group that suffers from perennial allergenic rhinitis, which is a year-round sensitivity to dust mites, pets and indoor moulds. Research shows that children and adolescents are the most affected and that genetical and environmental factors play a key role in the disease. Environmental factors include rain, wind, temperature and sunshine. For example, dry and warm days with low humidity cause a very high release of pollen. Rain reduces the pollen count, as it attracts pollen grains and removes them from the air. Family history of asthma, hay fever or eczema plays a key genetical role to the disease. For instance, in identical twins, if one of them has hay fever, then the other will have hay fever because identical twins share the same genes. With fraternal twins, if one has hay fever, it is 50% likely that the other will as 50% of fraternal twins are equal.
Immunological response:
Pollen contains numerous factors that can trigger an innate immune response. These include pollen proteins, lipids and antigens. Exposure to the antigens results in the production of antigen-specific immunoglobulin E (IgE). IgE attach to mast cells and basophils which become sensitive to further antigenic exposure. On further exposure, the antigens bind to IgE causing degranulation of the mast cells and the release of a pro-inflammatory chemical, histidine. Histidine causes an inflammatory response which is responsible for the symptoms of hay fever.
Can you differentiate hay fever from the common cold?
This table shows the main difference between allergic rhinitis and a common cold:
Adapted from: Hayfever, chapter 23 [Assessed online] https://www.pharmpress.com/files/docs/Ch-23_Website.pdf
What can you do to reduce the symptoms?
Here you can find some tips that will help you to reduce your hay fever symptoms:
1. Put Vaseline around your nose to trap the pollen.
2. Wear sunglasses and a mask to stop pollen getting into your eyes and nose.
3. Shower and wash your hair after arriving home and change your clothes.
4. Keep the windows closed when there is a lot of pollens outside.
Medical treatments:
If the symptoms are severe, it is recommended to take medication. The most suitable treatments for hay fever are antihistamines. Antihistamines act by blocking the chemical histamine, which causes the inflammation. There are two types of antihistamines: sedating and non-sedating. Non-sedating antihistamines are more recommended than the sedating one, as they prevent you from feeling drowsy and distracted from your work. However, this can be avoided if you take the medication before going to sleep. Another recommended treatment is the nasal steroid spray, which is useful for those who suffer from nasal symptoms. It is recommended to take the spray before the hay fever season begins and used throughout the remainder of the season. Finally, eye drops are another treatment particularly suggested for those suffering from itchy eyes. However, if you suffer from severe allergy and the treatments mentioned above have not worked for you, you can undertake immunotherapy. Immunotherapy consists of the injection of an allergen extract into your skin or orally. This therapy involves four to six injections before the hay fever season. The scope is to reprogramme your immune system to stop adversely reacting to an allergen.
References:
NHS (2021). Hay fever. [Assessed online] https://www.nhs.uk/conditions/hay-fever/
Alan, N (2012). Managing symptoms in the Pharmacy (chapter 23: Hay fever). [Assessed online] https://www.pharmpress.com/files/docs/Ch-23_Website.pdf
Bpacnz (2009). Seasonal allergic rhinitis. Managing hay fever. [Assessed online] https://bpac.org.nz/BPJ/2009/November/docs/bpj24_hayfever_pages14-23.pdf
Thomsen, S F., Ulrik, C S., Kyvic, K O., Hjelmborg, J V B., Skadhauge, L R., Steffensen, I., Backer, V (2006). Genetic and environmental contributions to hay fever among young adult twins. Respiratory Medicine, vol.12 pp. 2177-2182.
NHS (2019). Hay fever self-care. [Assessed online] https://www.croydongp.co.uk/wp-content/uploads/2019/03/Hay-Fever-Self-care-19-Mar-2019-FINAL.pdf
Allergy UK (2021). Hay fever (Allergic rhinitis). [Assessed online] https://www.allergyuk.org/information-and-advice/conditions-and-symptoms/11-hay-fever-allergic-rhinitis
Sheikh, A., Panesar, S S., Salvilla, S., Dhami, S (2009). Hay fever in adolescents and adults. BMJ Clinical Evidence.
D’Amato, G., Cecchi, L., Bonini, S., Nunes, C., Annesi-Maesano, I., Behrendt, H., Liccardi, G., Popov, T., Van Cauwenberge, P (2007). Allergenic pollen and pollen allergy in Europe. European Journal of Allergy and Clinical Immunology.