The Sweet Spring Challenge: Seasonal Allergies

The blessings of spring get mixed reviews from the estimated 35 million Americans who suffer from seasonal allergies. It's not easy to appreciate the miracles of nature through itchy eyes, runny nose and uncontrollable sneezing.

But what actually causes seasonal allergies? And what are the worst offenders? Below Dr. Gillian Shepard, a clinical associate professor of medicine at Weill Medical College of Cornell University, talks about the arch nemesis of carefree springtime- the seasonal allergy.

What are "seasonal allergies"?
People with seasonal allergies are allergic to something that's in the air for just part of the year. For example, people are often allergic to tree pollen, and the allergy only occurs when the trees produce their flowers and pollen, which lasts for several weeks in most places.

Some very common seasonal allergies are triggered by tree pollen in the springtime, grass in the spring through summer and then ragweed and other weed pollens in the fall.

Which trees cause the worst seasonal allergies?
Almost any tree is capable of inducing allergic reaction if you're programmed that way. In different parts of the country, people will react to different trees depending on what's there. For example, on the east coast, it is very common to be allergic to birch, oak and maple tree pollen. If you go to the western states, you may find that the cottonwood, poplar, and aspen trees are much more of a problem.

And of course the area where you live will determine when you have a problem. It takes from around February to the end of May for the tree pollen season to work its way up from Florida up through Maine. Allergy sufferers should be careful not to plan trips that take them in the direction of the tree pollen.

How long is the season in the Northeast?
The Northeast is particularly afflicted by tree pollen. There is so much of it that the average person is familiar with the sight of cars covered with yellow pollen during late April and early May.

Also when an allergic person will suffer depends on which tree they're allergic to. Some of them will pollinate in mid-April, and others will not pollinate until later, toward the end of May approaching Memorial Day.

Some very unlucky people that are sensitive to all these different tree pollens may have a tree pollen season in the Northeast that goes for 6 weeks. Others, if they're only sensitive to one type of pollen, might have symptoms only for 3 weeks during that time.

Do all season allergies- grass, ragweed, tree pollen- affect people the same way?
The symptoms one gets from tree pollen allergy are exactly the same as grass, ragweed, even symptoms from dust mite or cat allergy. You breathe the allergy substance in and an allergic reaction ensues, giving you the stuffy nose, sneezing, itchy eyes and so on.

What factors influence day-to-day allergic reactions?
The environment is absolutely critical. First the obvious, there is a lot less pollen inside than outside. But it's also important to remember that pollen can be sucked in through filter systems, so that if you have an air conditioning unit, you should change the filters frequently. You should also try and keep the windows closed to keep the pollen out.

The environment also has a bearing in a lot of other ways. For example, it is now clear that if you live in an area where the ozone level is high, you will be more sensitive to the allergy substance. For example, if normally it takes a larger exposure to grass pollen for it to induce allergy symptoms but the ozone level is high, a minimal exposure might make you sneeze and itch.

Another factor that influences when somebody reacts is if they have any sort of a viral infection, like the common cold. The inflammation that results from a cold causes tiny little cracks in the lining of the nose and sometimes in the chest, and that may allow pollen to get through the lining. This may, in turn, trigger an allergy reaction, or it may rev up an allergy reaction that's already occurring.

What causes oral allergy syndrome?
A lot of people don't realize that there are cross-reactions between plants such as tree pollen and other foods, like fruits and vegetables. For instance, in the case of birch tree pollen, there's a direct cross-reaction with various fruits, particularly apples and peaches. When someone has an allergy, the immune system cannot distinguish between the pollen of birch trees and the pollen of the fruits. So if somebody eats an apple or a peach, they immediately encounter the pollen and it induces a lot of itching and tingling in the mouth.

It only happens with raw fruits, because when they are cooked you break down this allergy protein. So people who have the oral allergy syndrome, particularly to fruits and occasionally to some vegetables, very commonly have allergy to birch tree pollen.

And if you treat those patients with allergy shots, then this oral allergy syndrome settles down a great deal. The oral allergy syndrome is also much greater in May. If someone is breathing in a lot of the pollen of birch trees in May, then their immune system revs up at that time and it makes them much more sensitive to food with similar pollen.

That's just one example of cross-reactions between pollens and various other food substances. For example, patients who are allergic to ragweed pollen in the fall often will have a cross-reaction allergy to chamomile and may have problems drinking chamomile tea.

When should a person who has seasonal allergies see a doctor?
In most cases, the symptoms of springtime allergies are fairly straightforward; nasal, eye symptoms, and can be handled certainly by over-the-counter medications, or if not, very easily by prescription medications.

Anyone with seasonal allergies should consider seeing a doctor if they're worried about their symptoms, if they seem unusual or if they're not relieved by over-the-counter medications.

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