What is Seasonal Allergy?
The phrase seasonal allergy is frequently used in commercials trying to sell a product that is designed to reduce allergy symptoms such as runny nose and itchy, watery eyes. What is seasonal allergy and what do you need to know to combat it?
You may be one of the unlucky sufferers of seasonal allergy, often called hay fever, which probably affects upwards of 30% of the world’s population. The term hay fever is really a misnomer since hay isn’t likely to be the actual culprit and you don’t develop a fever. The term came into use apparently when individuals who were cutting and harvesting field hay developed signs of an allergic reaction: itchy, watery eyes; a runny nose; sinus congestion; post-nasal drip and its associated cough. (As an aside, this was probably due to grass pollen, dust, and/or mold spores that were present in large amounts in the field and which became airborne as the hay was cut and bundled.)
The correct term to use for this unfortunate condition is seasonal allergic rhinitis. If you suffer with these typical symptoms throughout the year, then you have a condition called perennial allergic rhinitis. In medical parlance the eye symptoms are properly referred to as allergic conjunctivitis; the inflammation (which causes redness) of the whites of the eyes. In addition to making you very uncomfortable, allergic rhinitis and conjunctivitis can be forerunners to other diseases including sinusitis and asthma. The signs or conditions which accompany allergic rhinitis can make thinking and concentrating difficult, which can lead to poor performance in school and/or on the job.
If you suffer from allergic rhinitis or allergic conjunctivitis, you should visit your allergist to find out what it is you are allergic to. Since there are numerous materials that can trigger an allergic reaction (pollen, dust, mold spores, pet dander, mites, etc.), it is important to determine what you need to try and avoid, and determine if there are medications or treatments that you can use to reduce symptoms or prevent the allergic response.
In this blog I am dealing only with seasonal allergies, seasonal rhinitis, caused by pollen. The goal is to provide you with information about the likely pollen trigger(s) based upon the time of year you most often develop allergic rhinitis. See the table at the end of this blog for a list of some of the common pollens that cause allergic rhinitis and the times when they are likely to be in the air.
In general, individuals with allergic rhinitis/conjunctivitis during the late winter and early spring are probably allergic to one or more tree pollens. It is during this time of the year that numerous trees are in flower and produce lots and lots of pollen that is transported in the air. This is also the period during which the cone bearing trees like cedars and pines are producing large amounts of pollen that become airborne. The principal types of pollen in the air that trigger allergic reactions are cedar, elm, alder, mulberry, oak, willow, cottonwood, ash, birch, hickory, pecan, sweetgum, and maple. Pine trees are producing large amounts of pollen during the spring but this is rarely the pollen responsible for triggering allergy symptoms.
Allergic reactions in individuals resulting from grass pollen are usually most prevalent during the period mid-spring to early summer. Individuals who have allergies to weeds are most often affected during the summer and early fall, with the principal cause being pollen from various plants in the family Asteraceae (the sunflower family); the principal species causing allergic rhinitis is ragweed. It should be noted that there are some species of weeds which produce pollen that cause allergic rhinitis during the spring and early summer instead of autumn.
It is important to keep in mind that the start and end dates for particular pollen types will vary slightly from year to year but generally follow the patterns described above. The amount of pollen in the air is very much influenced by weather conditions such as temperature and precipitation. Typically one finds those years with high rainfall, particularly if the rainfall is spread out over long time periods, associated with lower pollen levels in the air.
Based upon skin test reactions of seasonal rhinitis sufferers, it appears that the principal types of pollen causing seasonal rhinitis are weeds, perhaps as high as 60-75%. The major weed pollen causing allergic rhinitis is ragweed. The next most frequent type of pollen causing seasonal rhinitis based upon rhinitis patients having a positive skin test reaction is grass. Some 40% of seasonal rhinitis patients have a positive skin test reaction to grass pollens. The type of pollen eliciting a positive skin test most infrequently (approximately 10%), and hence the least likely culprit causing seasonal rhinitis is tree pollens.
H. Wayne Shew, Ph.D.
NAB certified counter
BSC/AAAC Collection Station—Birmingham, Alabama
If you feel you are suffering with seasonal allergies, contact Alabama Allergy & Asthma Center at 205-871-9661.