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Friday, April 20, 2012

Seasonal Allergies

Author: Dr Paul Nadler University of California San Francisco 2008-07-22

Seasonal Allergies: Itchy eyes, runny nose and sneezing are common springtime symptoms for people with seasonal allergies. This article will explain what causes them, how to treat them, and when to see a clinician.

Introduction


For many people, springtime brings more than blooming flowers and warmer weather. It heralds a bloom of unpleasant symptoms such as runny nose, watery and itchy eyes, and sinus congestion.  For people sensitive to pollens released by plants, these unpleasant symptoms may not be restricted to just one season a year. They can recur in summer, fall, winter, or intermittently through the year.

People who have an allergic reaction to outdoor plant pollens suffer from a medical condition called seasonal allergies.  Another term for this condition is “hay fever.”  At least 10% to 25% of people in the United States react to pollens, and the incidence is rising.    

Seasonal allergies are caused by a person’s immune system overreacting to pollens that are released into the air during the season when plants reproduce.  (Some patients may also react to mold spores, but this usually causes allergic symptoms year-round).

These pollens lodge in the conjunctiva- the membrane that lines the eyelids and covers the whites of the eyes, or the lining of the nasal passages.  Therefore, they commonly produce a combination of ocular and nasal symptoms.  Taken separately, the allergic reaction of the eyes is called “allergic conjunctivitis”; the reaction of the nasal passages is called “allergic rhinitis.”  Most affected people suffer symptoms in both areas, but for some, symptoms in one area can predominate.

Common symptoms of allergic conjunctivitis:
•    Tearing and burning of the eyes and eyelids
•    Itchy, red eyes
•    Swelling and redness of the eyelids
•    A stringy or “ropy” or thin discharge from the eyes (not pus)
•    The skin below the eyes can swell and turn bluish (called “allergic shiners”)

Common symptoms of allergic rhinitis:
•    Runny nose with clear, watery mucus
•    Loss of taste
•    Sinus congestion

Other symptoms:
•    Hoarse voice
•    Popping of the ears
•    Itchy nose and throat
•    Fatigue and headache

The underlying problem that causes these symptoms is an overreaction of the patient’s immune system.  Inhaled pollens, or pollens that directly contact the lining of the eyes, are processed by certain cells of the immune system and a specific type of antibody is created, called IgE.  This IgE causes other cells of the immune system, principally mast cells, to release histamine.  Histamine is a chemical that leads to teary eyes, runny nose and itching.  If swollen nasal membranes block the increased mucus it causes symptoms of sinus congestion.  It some cases, the blocked mucus that builds up can be secondarily infected by bacteria or viruses. It is sometimes difficult to tell if a patient’s symptoms of congestion are caused by a severe allergy or a sinus infection.  But, if a patient develops a fever, it is a good sign that an infection has developed and medical attention should be sought.

What Causes Seasonal Allergies?


Although the commonly used term for seasonal allergies “hayfever” suggests the cause of the problem, this term is very misleading.  Only a few people are reacting to hay. Rather, most people respond to pollens from plants, grasses, and trees.  And it is very uncommon for allergies to cause a fever! A patient with a runny nose or sinus congestion with fever is more likely to have a viral or bacterial illness.

Although spring is a classic time for people to suffer seasonal allergies, plants release pollens at various times of the year.  They vary in type and quantity depending on the specific plant, region, and whether it is a dry or wet year.

•    In the western United States mountain cedar is a main source of tree pollen from December to March
•    In the eastern, southern, and midwestern United States, the causes of symptoms in the spring include oak, elm, maple, alder, birch, juniper, and olive trees
•    In the early summer, people often react to pollens from grasses such as bluegrass, timothy, redtop, and orchard grass
•    In the dry Southwest, grasses pollinate later in the season 
•    Late summer, ragweed is a major cause of symptoms

Unfortunately, people may be sensitive to several pollens, so they may react periodically throughout the year.  Also, when a patient moves from one state to another, they may develop an allergic reaction to pollens in the new area, making their symptoms more frequent.

Diagnosing Seasonal Allergies


To distinguish which patients have seasonal allergies from those with a cold or sinus infection cause by viruses or bacteria,a clinician ask many questions to determine whether there is a pattern of recurrent symptoms or “triggers” that lead to symptoms. Specifically, a clinician will ask whether the symptoms of runny nose or itchy irritated eyes occur in a pattern that matches the release of pollens in the local area. The clinician will ask about past symptoms, when they occurred, how long they lasted, and whether any previous medication helped.   Some patients will have a very good understanding of what triggers their symptoms and, if known, should always share these with the examining clinician.

Other clues include the age at which a patient first developed symptoms- 80% of patients with allergic rhinitis first had a runny nose caused by allergies before age 20.  A family history of allergies is also a clue, as this condition tends to be hereditary.  A personal medical history of asthma or eczema also increases the likelihood that the symptoms of runny nose or teary eyes are caused by seasonal allergies instead of an acute viral or bacterial infection.

A careful physical exam will also help in diagnosis.  Eyes irritated by allergies usually produce thin clear discharge or a stringy ropy one.  These symptoms almost always affect both eyes at the same time.   The inside of the eyelids may become bumpy and white or yellow tissue can seem to grow up (vernal conjunctivitis).  Nasal discharge is thin and clear. Green mucus from the nose is more likely to be an infection.  To better separate an infection from an allergy as the cause of the nasal symptoms, the clinician may want to look up into the nose with a light.  In allergic rhinitis (a runny nose caused by allergies), the membranes develop a bluish red color instead of the usual bright red color seen in infection.  To better examine the nasal passages, a flexible fiberoptic scope may be used by clinicians experienced in this technique.  As mentioned previously, fever is very unusual in cases of congestion or runny nose caused by allergies.  Lymphadenopathy, commonly called “swollen glands” are usually caused by an infection, not allergies.

Laboratory Testing


One office test that can be used in diagnosing nasal allergies is to examine the nasal discharge under a microscope.  A special cell, called an eosinophil, which is produced by the body’s immune system during allergic reaction, can be seen in high number in the mucus of some people.  Unfortunately, this test is not very accurate.  A more specialized evaluation is skin testing for allergies.  Samples of pollen are injected or “pricked” into the skin of the patient.  An allergic reaction to the test confirms a patient’s sensitivity to the pollen. There is also a blood test known as the RAST test which tests the body’s immune reaction to a group of pollens.  It actually measures the antibodies (IgE) directed at known causes of allergies.  Even though this blood test is very high-tech and easy to order, it is not very sensitive, so some people with allergies may not be diagnosed by this test alone.  It is quite specific however.  So if it determines that a patient has an allergy to pollen, it is usually accurate. 

Unfortunately, it is not clear which patients with seasonal symptoms should have these tests performed.  Neither the World Health Organization, the American Academy of Allergy, Asthma and Immunology, nor the U.S. Agency for Healthcare Research and Quality have issued firm guidelines as to who needs these expensive, imperfect tests. 
The diagnosis of seasonal allergies still relies on a clinician taking a careful, detailed history of the patient’s symptoms and performing a thorough physical exam.  The decision to pursue these tests will be depend on many factors, including the severity of a patient’s symptoms, the patient’s response to medications, and the personal preferences of the patient and the treating clinician.

Treating Seasonal Allergies WITH Medication


Patients with mild symptoms of seasonal allergies can be effectively treated with oral medications called antihistamines.  These drugs work by blocking the release of histamine, which is released by the patient’s immune system during an allergic reaction.  Histamine is responsible for the symptoms of swelling, tearing, runny nose, and itching.  Antihistamines are available both by prescription and over-the-counter.  First-generation antihistamines, such as diphenhydramine, are very effective, but can cause excessive sedation for many patients.  They should not be taken prior to operating dangerous machines.  The newer antihistamines such as loratadine and fexofenadine also work effectively and cause little or no sedation.  

For patients with more severe or localized symptoms, putting the medicine to work directly at the site of the problem is helpful.  For allergic conjunctivitis, antihistamine eye drops are a useful treatment.  Other types of eye drops that may be used work by stabilizing mast cells- preventing the release of histamine. They are effective for mild symptoms and are very safe for long-term use.  Also, nonsteroidal antiinflammatory eye drops (NSAID) are commonly used.  Some of the newer, and most effective, eyedrops are medications that both stabilize mast cells and oppose the action of histamine. If ocular symptoms are very severe, drops containing steroids may be necessary.  But these drops must be prescribed and used with caution.  It is very important to ensure that a patient does not have glaucoma (too much pressure in the eye) before using these drops as they can raise intraocular pressure.  Also, to avoid causing damage to the lens (cataracts) with long-term use, certain types of steroid drops may be preferred.  Steroid drops should only be prescribed by an ophthalmologist to ensure safety.

If the symptoms of nasal congestion or runny nose are prominent, a prescription nasal spray containing a steroid should be used.  These medications are effective in relieving both the runny nose and the congestion, and are more effective than oral antihistamines.  The newer preparations have very little absorption into the body so they are safe to use on a long-term basis.   To get the maximum benefit, the spray must be used properly. It is important that the medication goes into the nasal passages, and does not drain down the back of the throat.  Do not tilt the head back when using them.  Remember- “spray while looking at your toes.”  It may help to hold the other nostril closed when spraying.  Time the release of spray so you “sniff” up the medication gently into the nose.  And excessive mucus crusting of the nasal passages should be cleared with nasal saline first in order to improve contact of the medication with the nasal lining.  Some people may want to use an oral decongestant, such as pseudoephedrine, for few days before a nasal steroid is used in order to clear the passages of the nose. 

Some common side effects of nasal steroids include a dry nose or an unpleasant taste.  Dry nasal passages can be worse in the winter, and can be alleviated with saline nasal spray.  In some cases, a different formulation of nasal steroid should be prescribed.  Petroleum jelly, applied to the nose, can also help.

For patients with milder nasal symptoms, there are mast cell stabilizing nasal sprays, such as cromolyn, and a nasal antihistamine called azelastine.  Cromolyn is very safe, but less effective than steroid nasal sprays.   Azelastine is effective on both a runny nose and congestion. It starts to work within minutes, and can be used on an “as needed” basis.  It can be sedating if used more often than recommended, however.

Both steroid nasal sprays and mast cell stabilizing sprays may take a few days to work, with maximum benefit occurring in 10 days to two weeks.

The over-the-counter nasal sprays such as oxymetazoline are also effective, but are only safe for short-term use.   As a result, they are not advised for treating seasonal allergies, as the pollen season may last weeks and sometimes longer.  Patients may use them for the first two or three days of treatment while waiting for the effective, but slower acting, steroid nasal sprays to take effect.  These over the counter nasal sprays should NOT be used for more than three days however.  They work by constricting the blood vessels in the nasal passages.  After a week, these blood vessels compensate by swelling more than usual, causing “rebound congestion.”  A patient can get into a vicious cycle of temporary relief from a nasal spray followed by worsening congestion.  This problem is called by the medical term “rhinitis medicamentosa.”  It can be prevented by not using the over the counter nasal sprays for more than three days straight.  This condition does not occur with prescription nasal sprays, even after long-term use.

Over-the-counter decongestants, such as pseudoephedrine, can help relieve symptoms of congestion.  But they must be used with caution- they can raise blood pressure, make benign prostate hyperplasia worse acutely (leading to urinary obstruction in some cases), speed up the heart, and make it difficult to sleep.  They are sometimes useful if taken for a short time or temporarily with prescription medications to give some rapid relief of symptoms.

For patients with very severe local symptoms or general symptoms of fatigue and headache, a short course of an oral steroid may be prescribed (or an injected steroid can be given in the office).  While effective, they should not be used unless more common and milder medications have been tried.  Long-term oral or injected steroid use can weaken bones, raise blood sugar, increase pressure in the eye, and cause other changes in the body.   (These are not the same steroids as used by bodybuilders; they do NOT increase muscle mass).   As mentioned before, the steroid in nasal sprays are safe for long-term use as there is little absorption.  These adverse effects result from use of oral steroids, such as prednisone, over a long period.

A newer type of treatment involves blocking the reaction of the immune system to pollens with leukotriene inhibitors.  These work on a different part of the immune system than antihistamines or steroids and can be added to these treatments.  They are less effective, however, and most patients will not get adequate relief if used alone.

The decision as to which medicines are most effective for any given patient and how long to use them are best made by a clinician who is experienced in treating seasonal allergies.  Medication effectiveness can be improved if the patient follows up with the same treating clinicians so adjustments in the regimen can be made as the patient’s symptoms improve (or persist).  Most primary care clinicians can treat seasonal allergies effectively.  But if the patient’s symptoms do not respond despite a trial of several effective medications, or are particularly severe, consultation with a specialist in Allergy and Immunology is important.

Immunotherapy (“allergy shots”)


This is a specialized form of treatment in which small and increasing doses of allergen are given by injection.  In time, the body desensitizes to the allergen, and therefore the patient reacts less strongly when exposed to plant pollens.  These treatments, performed by an allergist, require many repeat visits, and can be expensive.  They also may require maintenance shots to be given for years after the initial course of therapy.  They carry a small risk of a sudden severe allergic reaction- 6 of every 10,000 injections.  They are most appropriate for patients with severe symptoms not controlled adequately with medication, or patients who have significant side effects from the medications.  They are sometimes very helpful in children to prevent worsening sensitivity to pollen, and to reduce the use of medications that can be sedating or affect their development physically or intellectually.

Treating Seasonal Allergies WITHOUT Medications


1)    Do not rub the eyes.  The mechanical pressure of rubbing can cause mast cells to release histamine.
2)    Use artificial tears to dilute and remove allergens.  Do not use over the counter drops that contain vasoconstrictors on a regular basis.  Occasional intermittent use of vasoconstricting drops is O.K., but save them for that special time when you want to reduce redness for a meeting or a social engagement.
3)    Use cool compresses regularly to soothe and reduce swelling of the lids.
4)    Avoid contact lens use (allergens can stick to them and make your symptoms worse)
5)    Limit outdoor exposure during times of pollen release.
6)    Use air conditioners to filter the air. Ensure that vents and heating ducts are cleaned regularly.
7)    Keep windows closed during peak seasons- both car and house.  This is especially important on windy days.
8)    Use saline nasal spray to remove mucous crusts in the nose.  Removing these crusts with saline spray also lets steroid nasal sprays work better as they can better contact the nasal lining.
9)    Saline lavage, with a bulb syringe, or a NETI pot, may help some people who experience a lot of congestion or postnasal drip, and are willing to learn the technique. (An explanation of the equipment and technique, as well as a short video is at:  http://www2.med.umich.edu/prmc/media/newsroom/details.cfm?ID=142 )
Warmed saline should be used.  The solution can either be bought or mixed at home.

More information resources on the Web

    •     National Library of Medicine
           www.nlm.nih.gov/medlineplus/healthtopics.html
    •     National Institute of Allergy and Infectious Diseases (NIAID)
           www.niaid.nih.gov
    •     Allergy, Asthma, and Immunology Online
           www.acaai.org
    •     American Academy of Allergy, Asthma, and Immunology
           www.aaaai.org

The American, Academy of Allergy, Asthma and Immunology has a Web site that tracks pollen counts:
http://www.aaaai.org/nab/index.cfm

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