Hay Fever Causes
Hay fever, like all allergic reactions, is caused by allergens, foreign "invaders" that enter your body by inhalation, by swallowing, or through your skin.
- In hay fever, the allergens are airborne substances that enter your airways (mouth, nose, throat, and lungs) via your breathing and the linings of your eyes and sometimes ears via direct contact.
- Most of the time it is difficult to identify a specific allergen.
- Once these allergens come in contact with your airway, the white blood cells of your immune system produce antibodies to the offending substance. This overreaction to a harmless substance is often called a hypersensitivity reaction.
- The antibody, called immunoglobulin E, or IgE, is stored on special cells called mast cells.
- When the antibody comes in contact with the corresponding antigen, they promote release of chemicals and hormones called "mediators." Histamine is an example of a mediator.
- It is the effects of these mediators on organs and other cells that cause the symptoms of the allergic reaction, in this case hay fever.
- The most common allergens in hay fever are pollens.
- Pollen is small particles released by plants.
- It is moved around by wind to other plants of the same species, which it fertilizes so that the plant can bloom again.
- Pollens from certain types of trees, grasses, and weeds (such as ragweed) are most likely to cause reactions. Pollens from other types of plants are less allergenic.
- The time of year when a particular species of plant releases pollen, or "pollinates," depends on the local climate and what is normal for that species.
- Some species pollinate in the spring and others in the late summer and early fall.
- Generally, the farther north a plant is, the later in the season it pollinates.
- Variations in temperature and rainfall from year to year affect how much pollen is in the air in any given season.
- The other common allergens in hay fever are molds.
- Molds are a type of fungus that has no stems, roots, or leaves.
- Mold spores float through the air like pollen until they find a hospitable environment to grow.
- Unlike pollen, however, molds do not have a season. They are present throughout the year in most of the United States.
- Molds grow both outdoors and indoors.
- Outdoors, they thrive in soil, vegetation, and rotting wood.
- Indoors, molds (usually called mildew) live in places where air does not circulate freely, such as attics and basements, moist places such as bathrooms, and places where foods are stored, prepared, or discarded.
- The amounts of pollen and molds in the air are measured daily in many areas around the United States and reported by the National Allergy Bureau.
- The pollen and mold counts at which people develop allergic symptoms vary quite a lot by individual.
- Pollen and mold counts are not very helpful in predicting how a specific person will react.
- Risk factors for hay fever include:
- Family members with hay fever
- Repeated exposure to the allergen
- Other allergic conditions such as eczema or asthma
- Nasal polyps (small noncancerous growths in the lining of the nose)
- The allergens cause symptoms in an individual as he or she ages. Symptoms decrease in some allergy sufferers, but not all, as they grow older.
- Bodily changes of pregnancy may make hay fever worse.
Could I Be Allergic? Discover Your Allergy Triggers
Hay Fever Symptoms
The usual symptoms of hay fever include the following:
- Runny nose (clear, thin discharge)
- Congested ("stuffy") nose
- Postnasal drip
- Sensation of plugged ear(s)
- Watery, bloodshot eyes
- Itching of nose, soft palate, ear canal, eyes, and/or skin
- Trouble sleeping
When to Seek Medical Care for Hay Fever
Call your health care professional if you experience any of the following:
- Symptoms that do not improve with self-treatment
- Fever that does not subside
- Nasal secretions that are colored, thickened, or bloody
- Sore throat that gets worse
- Earache or ear discharge
Go to the hospital emergency department if you experience any of the following in conjunction with an allergic reaction:
- Very high fever
- Difficulty breathing
- Uncontrolled bleeding
- Discharge from the ear or severe earache
Hay Fever Diagnosis
Your health care professional will ask you questions about the following:
- Medical history, including allergies, asthma, and eczema
- Seasonal symptoms associated with specific geographic locations
- Family history of hay fever, asthma, and other allergies
He or she may take a drop of your nasal discharge, looking at it under a microscope for many immune cells called eosinophils, which increase dramatically in number during an allergic reaction.
An allergy specialist (allergist) may be able to determine the exact allergen causing your hay fever. He or she uses a skin test in which dilute solutions of various allergens are introduced into your skin. A positive reaction is indicated by a typical wheal and flare reaction (raised red bump).
Hay Fever Treatment
Hay fever does not always require medical treatment.
Hay Fever Self-Care at Home
Avoid known or suspected allergens.
Hay fever symptoms lend themselves to home treatment.
- Gargle with warm salt water, 1-2 tablespoons of table salt in 8 ounces of warm water, to soothe a mild sore throat.
- Take nonprescription antihistamines such as diphenhydramine (Benadryl) to relieve symptoms of sneezing, runny nose, and itchy throat and eyes. Caution -- these medications may make you too drowsy to drive a car or operate machinery safely.
- For stuffy nose, a combination of an antihistamine and a decongestant such as pseudoephedrine (Sudafed, Actifed) may work better.
Hay Fever Medications
Steroid Nasal Sprays
Examples of these include beclomethasone (Beconase), triamcinolone (Nasacort), and fluticasone (Flonase).
- These are not the steroids taken by some people to increase athletic performance.
- Sprays take a few days to work, but when they reach an effective level, they do a very good job of decreasing symptoms without causing drowsiness.
- They must be used daily if they are to work properly.
- Nonprescription antihistamines (diphenhydramine [Benadryl], clemastine [Tavist], and hydroxyzine [Atarax]) are the most commonly used drugs. Loratadine (Claritin), cetirizine (Zyrtec), and fexofenadine (Allegra) are long-acting, nonsedating antihistamines available without a prescription.
- These antihistamines are inexpensive and readily available. The effects do not last long.
- They may make you too drowsy to drive a car or operate machinery safely. You may start using them at bedtime. Drowsiness often lessens with continued, regular dosage.
- Many hay fever sufferers choose to take longer acting prescription antihistamines, such as fexofenadine (Allegra), loratadine (Claritin), and desloratadine (Clarinex). These drugs are more expensive, but they have to be taken only once or twice a day. The biggest advantage of these drugs is that they cause only mild sleepiness, if any at all.
- Montelukast (Singulair) is a leukotriene inhibitor approved by the U.S. Food and Drug Administration for treatment of hay fever.
- It is available with a prescription and comes in tablet, chewable tablet, or granule forms. The granules may be sprinkled directly on the tongue or mixed with cold or room temperature soft food like applesauce or pudding.
- Leukotrienes are powerful chemical substances that promote the inflammatory response seen during exposure to allergens. By keeping these chemicals from producing, leukotriene inhibitors reduce inflammation.
- Leukotriene inhibitors are particularly effective when used with an antihistamine.
- Available in aerosol (Nasalcrom) and in eyedrops (Crolom), cromolyn sodium makes your mucous membranes less sensitive to allergens.
- It gives better relief if you take it as a preventive measure, even when you do not have symptoms.
- Decongestants are available in oral versions (such as pseudoephedrine [Sudafed]), eyedrops, or sprays (such as phenylephrine [Sinex]).
- Eyedrops are effective for relieving annoying eye itch.
- Nasal sprays are very useful, especially in relieving nasal congestion. However, they can cause a rebound effect and inflammation called rhinitis medicamentosa if overused.
- Oral decongestants can cause high blood pressure, rapid heartbeat, and nervousness.
- Use all decongestants according to package instructions -- usually no more than 3 days.
Be sure to tell your health care professional if you are pregnant
, plan to become pregnant, or become pregnant while taking these medications.
For more information on medications, see Understanding Allergy and Hay Fever Medications
Other Therapy for Hay Fever
Immunotherapy (allergy shots) is an alternative if medical therapy is not helpful. Allergy shots do not always help, but they can improve symptoms in many people. They are best given by an allergist.
- Immunotherapy consists of a series of injections over several months. The shots contain very small amounts of the antigen causing the hay fever reaction. The idea is to minimize your reaction to the allergen by slowly decreasing your sensitivity to it in a controlled setting, which is usually the allergist's office.
- Allergy shots do not always work, but in general hay fever responds well to this treatment.
- Severe adverse effects are uncommon.
Your immune system changes over time. Sometimes your body naturally lowers its immune reaction to allergens.
Hay Fever Follow-up
- Follow the treatment recommendations of your health care professional. Give the medications a chance. Most of them work well but some take several days to reach full effectiveness.
- See your health care professional if you experience any complication of hay fever.
- Any adverse effects of the medications prescribed should also prompt a visit to your health care professional.
- Consult your health care professional periodically to see if new, better medications with fewer side effects are available.
- Periodic re-evaluation of your allergy sensitivity is also recommended to prevent further illness.
- If you would like to have allergy shots for desensitization, discuss it with your primary doctor or an allergist.
Allergies can best be described as:
Hay Fever Prevention
- You can't prevent hay fever altogether, but you can learn to cope with it.
- Follow the treatment recommendations of your health care professional. The medications are very effective but may take several days to reach full effectiveness.
- Moving to a new part of the country usually doesn't help. People who do this often find themselves with new allergies within a few years.
- Use air conditioning and limit outside exposure during hay fever season.
- Allergy shots may help reduce the severity of your symptoms.
- To keep from bringing your allergy indoors, do what you can to keep your home free of mold and other allergens.
Hay Fever Prognosis
Common complications of hay fever include the following:
- Secondary infection: This is a bacterial infection that occurs in tissues such as the mucous membranes of the nose, throat, or sinuses or the ear that have already been irritated and inflamed by the allergic reaction. Ear infection (otitis) or sinus infection (sinusitis) are common secondary infections of hay fever.
- Rebound nasal congestion (rhinitis medicamentosa): This may result from using decongestant nasal sprays more than twice daily for 3 consecutive days.
- Enlargement of lymph nodes in the nose and throat
- Decreased lung function
- Facial changes: Most of the facial changes are because of local inflammation and congestion. These are temporary and resolve with the treatment of the disease. These include facial swelling, redness around the nose, and allergic "shiners."
- The crease across the top of the nose caused by frequent nose wiping can persist in children with long-term hay fever.
Reviewed on 10/9/2019
Medically reviewed by Michael Manning, MD; American Board of Allergy & Immunology
Allergic rhinitis: Clinical manifestations, epidemiology, and diagnosis