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Symptoms and Signs of Hay Fever

Doctor's Notes on Hay Fever

Hay fever (also termed allergic rhinitis) is a non-specific somewhat misleading term (fever is not usually a symptom) that refer to the signs and symptoms many people develop with the change of seasons. Classic signs and symptoms of hay fever are itchy, puffy and watery eyes plus a red, stuffy nose that appears at the change of seasons, especially when heavy concentrations of pollen and/or mold spores are airborne. Other signs and symptoms may include sneezing, bloodshot eyes, fatigue, ear stuffiness and difficulty sleeping.

The cause of hay fever is the body’s overactive immune response to antigens on pollen, molds or other airborne compounds that trigger the production of chemicals like histamine that produce symptoms. These antigens can be eaten, swallowed, or contact mucus membranes where immune system cells recognize them as foreign substances and react.

Medical Author:
Medically Reviewed on 3/11/2019

Hay Fever Symptoms

The usual symptoms of hay fever include the following:

  • Sneezing
  • 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
  • Fatigue
  • Trouble sleeping

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 it 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
    • 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 that 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.

Allergies Myths and Facts About Seasonal Allergies Slideshow

Allergies Myths and Facts About Seasonal Allergies Slideshow

This is mostly a myth, with an element of truth to it. It used to be fairly common advice for allergy-sufferers to move to the desert. With their hot, dry climates, deserts are free from a lot of the usual suspects that cause seasonal allergies like ragweed and grass. However, apparently everyone listened. Desert communities like Las Vegas and Phoenix now feature many of the same allergenic plants found elsewhere.

You still may get some relief in a drier climate, though. More remote desert areas can have lower pollen counts, though some people are allergic to desert plants like sagebrush and Russian thistle. You may get some relief from dust, too. Scientists from North Carolina studied different areas around the U.S. for dust mites, the microscopic pests responsible for many indoor allergies. They found that the Great Plains and Mountain West regions—drier than the coasts—produced fewer dust mites.


Kasper, D.L., et al., eds. Harrison's Principles of Internal Medicine, 19th Ed. United States: McGraw-Hill Education, 2015.