Hay fever

Symptoms

Hay fever symptoms usually start immediately after you're exposed to a specific allergy-causing substance (allergen) and can include:

• Runny nose and nasal congestion
• Watery or itchy eyes
• Sneezing
• Cough
• Itchy nose, roof of mouth or throat
• Sinus pressure and facial pain
• Swollen, blue-colored skin under the eyes (allergic shiners)
• Decreased sense of smell or taste

Your hay fever symptoms may start or worsen at a particular time of year, triggered by tree pollen, grasses or weeds, which all bloom at different times. If you're sensitive to indoor allergens, such as dust mites, cockroaches, mold or pet dander, you may have year-round symptoms. Many people have allergy symptoms all year long, but their symptoms get worse during certain times of the year.

Although hay fever can begin at any age, you're most likely to develop it during childhood or early adulthood. It's common for the severity of hay fever reactions to change over the years. For most people, hay fever symptoms tend to diminish slowly, often over decades.

Causes

During a process called sensitization, your immune system mistakenly identifies a harmless airborne substance as something harmful. Your immune system then starts producing antibodies to this harmless substance. The next time you come in contact with the substance, these antibodies recognize it and signal your immune system to release chemicals such as histamine into your bloodstream. These immune system chemicals cause a reaction that leads to the irritating signs and symptoms of hay fever.

Seasonal hay fever triggers include:

• Tree pollen, common in the spring
• Grass pollen, common in the late spring and summer
• Weed pollen, common in the fall
• Spores from fungi and molds, which can be worse during warm-weather months

Year-round hay fever triggers include:

• Dust mites or cockroaches
• Dander (dried skin flakes and saliva) from pets such as cats, dogs or birds
• Spores from indoor and outdoor fungi and molds

Hay fever doesn't mean you're allergic to hay. Despite its name, hay fever is almost never triggered by hay, and it doesn't cause a fever.

Risk factors

The following factors may increase your risk of developing hay fever:

• Having other allergies or asthma
• Having a blood relative (such as a parent or sibling) with allergies or asthma
• Being male
• Being exposed to cigarette smoke during your first year of life
• Living or working in an environment that constantly exposes you to allergens — such as animal dander

Complications

Problems that may be associated with hay fever include:

• Reduced quality of life. Hay fever can interfere with your enjoyment of activities and cause you to be less productive. For many people, hay fever symptoms lead to absences from work or school.
• Poor sleep. Hay fever symptoms can keep you awake or make it hard to stay asleep.
• Worsening asthma. If you have asthma, hay fever can worsen signs and symptoms such as coughing and wheezing.
• Sinusitis. Prolonged sinus congestion due to hay fever may increase your susceptibility to sinusitis — an infection or inflammation of the membrane that lines the sinuses.
• Ear infection. In children, hay fever often is a factor in middle ear infection (otitis media).

Diagnosis

Positive reaction to allergy testYour doctor will ask detailed questions about your personal and family medical history, your signs and symptoms, and your usual way of treating them. Your doctor will also perform a physical examination to look for additional clues about the causes of your signs and symptoms. He or she may also recommend one or both of the following tests:

• Skin prick test. During skin testing, small amounts of material that can trigger allergies are pricked into the skin of your arm or upper back and you're observed for signs of an allergic reaction. If you're allergic, you develop a raised bump (hive) at the test location on your skin. Allergy specialists usually are best equipped to perform allergy skin tests.
• Allergy blood test. A blood test (sometimes called the radioallergosorbent, or RAST, test) can measure your immune system's response to a specific allergen. The test measures the amount of allergy-causing antibodies in your bloodstream, known as immunoglobulin E (IgE) antibodies. A blood sample is sent to a medical laboratory, where it can be tested for evidence of sensitivity to possible allergens.

References:

https://en.wikipedia.org/wiki/Allergic_rhinitis

http://www.medicinenet.com/hay_fever/article.htm

http://allergy-ireland.ie/hay-fever/

http://www.hayfever-relief.com

http://www.hse.ie/eng/health/az/H/Hay-fever/Treating-hay-fever.html