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Seasonal Allergies v. Year-Round Allergies - What Is the Difference?


Updated: September 8, 2008

Question: Seasonal Allergies v. Year-Round Allergies - What Is the Difference?

Seasonal allergies and allergic asthma act differently than year-round allergies. If you're wondering why and how, you're not alone.

Answer: The difference between seasonal allergies and asthma and the year-round variety is, first off, the time at which each occurs. People who suffer from year-round allergies and asthma have asthma symptoms and allergy symptoms all year long, through all 4 seasons. This is sometimes referred to as indoor allergies.

On the other hand, other people with allergic asthma and nasal allergies only suffer from symptoms during certain times, or seasons, of the year. For some people, it's only in the spring, while for others it might be during the hottest days of the summer or in the early fall. Or, for a few unfortunate people, it might be 3 out of the 4 seasons in a year.

No matter how long you have symptoms, if they only occur at certain times of the year, then they're what are often called outdoor allergies. Allergies are labeled indoor or outdoor to designate what triggers them.

Allergic asthma triggers are substances that set off allergy symptoms and / or asthma symptoms in sensitive people. Different kinds of triggers are found either mostly indoors or mostly outdoors. Examples of indoor triggers are:

  • animal dander, saliva and urine
  • dust mites
  • mold spores
  • insect allergens

As you can see, these are the types of things that can be in your home environment most any time. It doesn't matter how warm or cold it is; indoor allergens can thrive year-round in your home, office, or school. So they can also cause year-round allergy symptoms and / or asthma symptoms.

On the other hand, outdoor allergens are mostly present in high numbers when nature is greening and growing, and tend to die down during the colder, winter months in most parts of the world. Examples of outdoor triggers are:

  • tree, grass, and weed pollens
  • outdoor mold spores

A few other substances usually found outdoors can also set off symptoms, but these are considered to act more as irritants than triggers. That means that although they can cause symptoms, they more typically cause irritation to already inflamed airways. They don't actually trigger airway inflammation on their own. Examples are:

  • air pollution
  • vehicle exhaust
  • sawdust

Though different in several ways, the kind of treatment recommended to treat these types of allergies is the same. However, for year-round allergies, medication is generally taken daily all year; seasonal allergy sufferers may only use medication during the season triggers are present.

For people with asthma, treatment is generally year-round, even if the worst triggers are the seasonal kind. This is to maintain consistent control of the condition.


"Expert Panel Report 3: Guidelines for the Diagnosis and Management of Asthma." NHLBI Guidelines for the Diagnosis and Treatment of Asthma. 28 Aug 2007. National Heart Lung and Blood Institute. 18 Dec. 2007 <http://www.nhlbi.nih.gov/guidelines/asthma/asthgdln.pdf>

AAAAI, "Tips to remember: outdoor allergens." American Academy of Allergy Asthma & Immunology. 01 January 2006. AAAAI. 18 Oct 2007 http://www.aaaai.org/patients/publicedmat/tips/outdoorallergens.stm

"Tips to remember: indoor allergens." 2007. American Academy of Allergy Asthma & Immunology. 27 June 2008

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