What is Hay Fever, Know its Causes, Symptoms, Treatment, Prevention, Pathophysiology, Risk Factors
What is Hay Fever?
Hay fever is a common allergic condition that has symptoms similar to common cold and it is usually accompanied by sneezing, congestion, sinus pressure and runny nose. It is usually caused due to allergic reaction to certain airborne triggering agents such as pollen grain. Even though the symptoms of Hay fever may be similar to common cold, the cause of both the condition is quite different. Hay fever is caused as an immunological response to an allergic agent and common cold is caused due to viral infection. The symptoms of hay fever may be seasonal depending on certain time of the year when the amount of causative agent such as pollen grains is more in the environment.
The term hay fever is often misinterpreted. It is not an allergy to hay nor does the affected person necessarily develop fever. Hay is not a common allergen. Hay fever is basically an allergy caused by exposure to airborne allergens such as pollen, pet dander, dust mites and certain fungi which affects the nose, eye and even sinuses. Pollinosis is a specific term that is used to describe hay fever caused by pollen.
Symptoms of Hay Fever
The symptoms of hay fever vary from person to person and it also depends of the type of allergen he or she is allergic to. The hay fever symptoms may set off at different time of the year and depending on the abundance of the allergic substance in the air. For example, in case of hay fever caused by pollen, the symptoms are more prevalent at that time of the year when pollen count in the air is more.
The most commonly encountered symptoms of hay fever include:
- Watery eyes
- Itchiness in throat
- Itchiness in nose
- Runny nose
- Blocked nose
- Generalized weakness and headache
- Excessive sweating
- Difficulty with sensation of smell and taste
- Facial pain and sinus blockage
- In severe cases, the itchiness spreads from the throat to the nose and ears.
- In some cases, hay fever can also be associated with symptoms like generalized fatigue, tiredness, irritability as well as insomnia.
- In asthmatic patients, hay fever worsens their wheezing and breathlessness. In some cases, the symptoms of asthma are seen only when they have hay fever.
Causes and Pathophysiology of Hay Fever
Hay fever is caused when our immune system in unable to differentiate between a harmless foreign material and a threat. The body reacts on exposure to the foreign substance and a series of immunological reaction takes place. An antibody called as immunoglobulin E is produced as part of the defence mechanism. This is followed by release of the chemical histamine. A few examples of hay fever triggers and associated peak time are mentioned below:
- Grass Pollen Causing Hay Fever: These tend to affect individuals in the late spring and in summer.
- Tree Pollen as a Cause of Hay Fever: These affect individuals during spring season.
- Hay Fever due to Weed Pollen: Hay fever due to weed pollen is commonly noticed during Fall/Autumn.
- Fungi and Mould Spores Causing Hay Fever: This type is mostly common during warm weather.
Risk Factors for Hay Fever
The chances of developing hay fever increases with the following risk factors:
- Genetic Inheritance as a Risk Factor of Hay Fever: The risk of developing hay fever is higher if there is family history of hay fever or other similar allergies.
- History of Other Allergies: Individuals who are known to have other allergies are at higher risk of developing hay fever.
- Underlying Condition Such as Asthma as a Risk Factor: Asthmatic patients tend to suffer from hay fever more than others.
- Gender and Age: It has been noticed that hay fever usually affects younger boy's more than younger girls. Studies have shown that boys are affected by hay fever at least twice more than girls before reaching adolescence. However, post adolescence girls are affected more than boys.
- Season of Birth: Usually, people born during the seasons when there is more pollen in the environment suffer from hay fever more often than people born during other time of the year.
- Passive Smoking as a Risk Factor for Hay Fever: Exposure to passive smoking or second hand smoke also contributes to hay fever. Children who are exposed to passive smoking especially during the first few years of life are at higher risk of developing allergic rhinitis.
- Order of Birth: It has been seen that the incidence of hay fever is higher among the first born child than the others.
- Number of Siblings: Babies with no siblings or one sibling develops hay fever later in life more than other children born to bigger families.
- Children in High Income Families: Children born in families following a high standard of living are at higher risk of developing hay fever as they grow up.
The last 3 risk factors are usually due to higher risk of developing childhood infections and autoimmune issues.
Treatment and Management of Hay Fever
Hay fever is usually treated by medications that are easily available over the counter. In many cases, a combination of multiple drugs tends to provide better relief. The most common choice of treatment modality includes:
Antihistamine Medicines to Treat Hay Fever
Antihistamine sprays and tablets are easily available over the counter. As the name indicates, antihistamine arrests release of the chemical called histamine. These drugs often provide relief to runny nose, itchiness and sneezing. They do not work in case of blocked nose. Example of over-the-counter antihistamine drugs includes Claritin, Alavert, Zyrtec etc.; example of prescription drugs includes Allegra and Astelin. Drugs like Astelin can be used upto 8 times a day. However, most of these drugs are associated with drowsiness and foul taste in mouth.
Eye Drops to Manage Hay Fever
Eyes drop containing cromoglycate helps is reducing itchiness and inflammation in the eyes.
Nasal Corticosteroids for Hay Fever
These are very effective in the management of inflammation caused by hay fever. Examples include Flonase, Nasonex, Beconase and Veramyst. These drugs may not act immediately and may take about a week before bringing an improvement in symptoms. In some cases, it may have mild side effects such as foul taste, foul odour and nose irritation.
Corticosteroids to Treat Hay Fever
In severe cases of hay fever, oral corticosteroids such as prednisone are prescribed. However, these drugs should be used for short period of time and with utmost caution in view of the side effects associated with them.
Immunotherapy for Hay Fever
These are allergy shots that are given to the patient to gradually desensitize the patient's immune system against a particular allergen. Small dosage of the known allergen is given and over a period of time the dosage is increased. This usually provides long term relief and it also helps in prevention of asthma and other allergies. In the past, few allergists have started considering sublingual immunotherapy for management of hay fever.
Alternative Therapies for Hay Fever
Alternative therapies such as acupuncture, homeopathy etc. can also be considered for management of hay fever.
Epidemiology and Prevalence Rate of Hay Fever
It has been estimated that in United States, about 7.8% of individuals above the age of 18 suffer from hay fever. Studies have shown that 7.5% of the adult population i.e. about 17.6 million in the United States are diagnosed with hay fever every year; and about 9% of the younger population i.e. 6.6 million children are diagnosed with hay fever every year. A study done in 2010 states that white children are more prone to hay fever (10%) than black children (7%).
Hay fever may be seasonal or perennial; symptoms are usually more common in spring, summer and early fall.
Diagnosis of Hay Fever
Diagnosis of hay fever is done based on the signs and symptoms demonstrated by the affected individual. A detailed case history is taken to understand any recent history of exposure to known allergen. Intervention by an allergist or an immunologist is often helpful. A blood test and a skin test are usually done for determining the allergen and for planning out the mode of treatment.
- Skin Test for Hay Fever: This test is done by pricking the skin with a small amount of suspected allergen after which the amount of immunoglobulin E (IgE) antibodies produced by the body is measured. In positive cases, there is elevated level of IgE antibodies.
- Blood Tests to Detect Hay Fever: This test is done to measure the level of immunoglobulin or IgE in the blood. If the level is close to zero it means there is no sensitivity; however, if the level is 6 it indicates high sensitivity and occurrence of Hay Fever.
Prevention of Hay Fever
Not much can be done to prevent the development of hay fever. However, individuals known to have hay fever can avoid worsening or flare up of the condition by limiting their exposure to the known allergen. The following precautionary methods are suggested for prevention of hay fever:
- Being aware of the elevated pollen count during the susceptible months. It has been noticed that the pollen count is usually high during humid, windy and non-rainy days; and also during early evenings.
- Avoid exposure to pollen grains while being indoor by shutting the windows and doors when the pollen count is high.
- Avoid lawn mowing and gardening to limit contact with pollen grains and prevent hay fever.
- Wash hands and eyes frequently with water to prevent lodgement of pollen.
- Wear protective clothing such as hats, scarfs, masks, glasses etc. while going outdoor during susceptible season.
- Install pollen filter in cars to prevent hay fever.
- Avoid indoor plantation and avoid flowers inside the house or work place.
- Avoid carpets and keep the surrounding dust free.
- Quit smoking and limit exposure to smoke (passive smoking).
- Avoid pets or contact with fury animals.
Hay fever is a common medical condition which is caused due to exposure to air borne allergen which triggers the immune system leading to an allergic reaction. It is commonly characterised by symptoms similar to common cold. Hay fever can easily be treated with certain medications and the condition can be prevented by taking precautionary measures to limit exposure to the known allergens.
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