Hay fever (allergic rhinitis)

What it is

Hay fever is the everyday name for allergic rhinitis: a set of nose symptoms caused by an immune system that overreacts to things in the environment that most people tolerate.¹ Despite the name, it is not necessarily a reaction to hay, and it does not cause a fever.¹

In allergic rhinitis, the immune system overreacts to a usually harmless substance by making antibodies called immunoglobulin E (IgE). These antibodies travel to cells that release histamine and other chemicals, causing an allergic reaction.²

There are two types: seasonal and perennial, or year-round.¹ Seasonal allergic rhinitis is triggered by outdoor allergens such as pollen and mold spores. Some people have symptoms year-round due to indoor allergens from pets, mold, dust mites and cockroach residue, or a combination of both.²

Allergic rhinitis affects 40 million to 60 million Americans.¹ CDC figures for 2024 put seasonal allergy at 25.2% of US adults and 20.6% of children under 18.⁵

Symptoms

The main symptoms are a stuffy nose from blockage or congestion, a runny nose or postnasal drainage, itching (usually in the nose, mouth, eyes or throat), red and watery eyes, puffy, swollen eyelids, sneezing and cough.¹ Some people also get dark circles under the eyes.⁴ Fatigue is often reported too, due to poor sleep from a blocked nose.¹

Allergic rhinitis can also be associated with problems beyond the nose, such as decreased concentration and focus, sleep disorders and missed days of work or school.¹ In children, ACAAI says it is important that irritability or other symptoms caused by allergies are not mistaken for attention deficit disorder.¹

A cold can look much the same, and timing is one way to tell them apart. Hay fever symptoms can begin immediately after exposure to an allergen and continue as long as the exposure continues. A cold most likely begins a day or two after exposure to the virus and can last a few days to a week.¹ With hay fever, a runny nose will likely have a thin, watery discharge, while a cold may bring a thicker or yellowish discharge and a low-grade fever.¹

Itching is another clue. If your eyes, nose or ears itch, that also could be an allergy, and NIH’s comparison chart lists fever as “never” for an airborne allergy.⁶ Colds last about a week and cause less itching of the nose and eyes. Allergies usually occur at the same time every year and last as long as the allergen is in the air.³

Not every runny nose is an allergy. Many people with rhinitis symptoms do not have allergies.² Strong odors, pollution, weather changes, smoke and other irritants may cause symptoms of non-allergic rhinitis. It usually begins in adults and causes year-round symptoms.²

What triggers it

Seasonal symptoms can occur in spring, summer and early fall, and are usually caused by sensitivity to airborne mold spores or to pollens from trees, grasses or weeds.¹ Most of the pollen that causes allergic reactions comes from trees, grasses and weeds, which make small, light, dry grains that travel by the wind. Flowering plants that spread their pollen by insects do not cause allergic rhinitis.⁷

Throughout the US, trees produce the most pollen from February through April, and in some regions, such as the South, trees may produce pollen as early as December or January. Grass pollen is most common from April through early June, and weed pollen appears in the late summer and fall.⁷ In the fall, a common allergen is ragweed or other weed pollens, or outdoor mold.¹ Mold spores that get into the nose cause hay fever symptoms, and allergic symptoms from fungus spores are most common from July to the first hard frost.⁸

Year-round symptoms are generally caused by dust mites, pet hair or dander, cockroaches or mold.¹ With cats and dogs, the allergy is to a protein found in the pet’s dander, saliva and urine.⁹ Underlying or hidden food allergies rarely cause year-round nose symptoms.¹

Irritants matter too. People with allergic rhinitis may be more sensitive to irritants such as smoke, perfume or cold, dry air.²

When to see an allergist

ACAAI says occasional allergies aren’t just something you have to live with, and that consulting an allergist is the most effective way to diagnose allergic rhinitis symptoms.¹ For chronic, long-term rhinitis, AAFA advises seeing a board-certified allergist if possible.³

An allergist finds out what you are and are not allergic to, which matters because many people with rhinitis symptoms do not have allergies. An allergist can also screen you for allergic asthma, which is common in people with rhinitis.²

Your allergist may start with a detailed history, looking for clues that help pinpoint the cause of your symptoms. You’ll be asked about your home and work, pets, family medical history, and how often and how badly your symptoms occur.¹ Then comes a physical exam and, most likely, allergy testing.² The test may be either a blood test or a skin test.³ The most common skin test is the prick or scratch test, in which a tiny drop of a possible allergen is pricked or scratched into the skin, and the results are known within 10 to 20 minutes.¹

Symptoms can also be triggered or made worse by allergens in the workplace, which is called occupational rhinitis. Common triggers include cleaning products, chemical fumes, certain types of dust and corrosive gases, and an allergist can help you identify them.¹

Breathing trouble is a different matter. Asthma symptoms like shortness of breath are often closely linked to allergies, and ACAAI says to seek emergency treatment if you have difficulty breathing or your skin turns blue.¹⁰

For questions about managing your symptoms, talk to an allergist.