Environmental & Seasonal Allergies

Written by Empire Medical Training Editorial Team

Medically reviewed by Sherry Wehner, MD Board-Certified Pathologist & Dermatopathologist; Aesthetic & Wellness Medicine

Updated June 2026 ·10 min read

Environmental allergies — also called inhalant or aeroallergen allergies — are the bread-and-butter of allergy practice. They are IgE-mediated hypersensitivity reactions to airborne particles a patient breathes in: pollen from trees, grasses, and weeds; the perennial indoor load of dust mites, mold, pet dander, and cockroach. They are common, they are chronic, and they meaningfully degrade quality of life — yet they are also among the most rewarding conditions a primary-care or aesthetics practice can take on.

The scale is striking. Allergies affect more than 56 million Americans and are the sixth leading cause of chronic disease in the United States. Approximately 30% of US adults have environmental allergies, and at least 10% have a food allergy. This guide sits within Empire's broader Allergy Testing & Treatment resource center and is written for clinicians who want an accurate, practical overview. It is clinical education, not medical advice, and nothing here substitutes for individualized clinical judgment.

What are environmental allergies?

An allergy is a hypersensitivity reaction that occurs when a patient is exposed to an antigen they are sensitized to. In environmental allergy, that antigen is something airborne. When a sensitized patient inhales it, the allergen binds IgE on the surface of mast cells, triggering degranulation and the release of histamine and other mediators. Histamine drives the familiar triad: nerve stimulation produces itch, vasodilation produces redness, and endothelial gapping in small vessels produces swelling. That single cascade explains nearly everything a patient describes — the itchy, runny nose, the watery eyes, the congestion.

Like almost all disease, the development of allergy is multifactorial, shaped by genetics, environment, and immunology. Genetics carries real weight: a child with one allergic parent is 30–50% more likely to develop allergies, and with two allergic parents that figure climbs to 60–80%. Environmental allergies are best understood by their two broad patterns, which is where any clinical workup starts.

Seasonal allergens: tree, grass, and weed pollen

Seasonal allergies are driven by pollens that surge at predictable times of year. The classic pattern across most of the US runs in three waves:

• Tree pollen — spring. Spring trees are among the most common seasonal triggers. In parts of the country, region-specific trees dominate: in Dr. Wehner's San Antonio practice, for instance, mountain cedar is a notorious winter-into-spring offender, while birch, oak, and ash drive spring symptoms elsewhere.
• Grass pollen — late spring and summer. Mixed grasses are a heavy mid-year load and one of the most frequently positive antigens on skin testing.
• Weed pollen — late summer and fall. Ragweed is the prototypical fall allergen and a major driver of the autumn allergy season.

The defining clinical feature of seasonal allergy is its calendar. When a patient reports symptoms that arrive the same weeks each year and resolve once the season passes, the timing itself is diagnostic information — which is why a careful history of when symptoms appear is as valuable as any test. Importantly, the specific grasses, trees, and weeds in any panel vary by region, a point that becomes central below.

Perennial allergens: dust mites, mold, pet dander, and cockroach

Perennial allergies persist year-round because their triggers are indoor and ever-present. These are the patients whose congestion never fully lifts. The major perennial allergens are:

• House dust mites. Extremely common and one of the most clinically important perennial allergens. Mites live in bedding, upholstery, and carpet, which is why home-environment questions matter so much in the history.
• Mold and fungi. Species such as Aspergillus fumigatus, Alternaria, and Cladosporium are common molds found in soil and damp indoor spaces; moisture and deteriorated buildings amplify exposure.
• Pet dander. Cat and dog are the headline triggers, but rabbit, horse, hamster, and animal feathers all contribute. Cat is one of the most common single positives on testing — and one patients are least willing to avoid.
• Cockroach. A significant and under-recognized indoor allergen, particularly relevant in asthma.

Because these allergens are tied to the patient's living and working environment, the history should probe pets, carpet, clutter, workplace chemical or irritant exposure, and signs of moisture. Many patients are not purely seasonal or perennial; the dust-mite-allergic patient who also reacts to spring trees is common, and recognizing both patterns shapes both avoidance counseling and the testing panel. For a fuller map of allergen categories, see types of allergens.

Why geography changes the allergy picture

One of the most practical points in allergy care is that allergy burden is not uniform across the country. Some regions of the US have substantially higher allergy rates than others, a pattern driven by climate, the dominant local flora, and mold load. Equally important, the specific trees, grasses, and weeds that matter shift from region to region — mountain cedar may dominate one market and be irrelevant in another.

This has a direct clinical consequence: the antigen panel a clinician tests should reflect the local pollen and mold profile. Allergen extracts are customarily tailored to the part of the country a practice serves, and a quality allergy lab will supply a region-appropriate full array of allergens. Testing for antigens that simply are not in your patients' environment wastes panel slots; missing the locally dominant ones misses real disease. Geography, in other words, is not background trivia — it is how you build a sensible panel.

Symptoms and conditions environmental allergies cause

Environmental allergies present through a recognizable cluster of chronic and recurrent conditions. The most common are conjunctivitis, sinusitis, rhinitis, eczema, and asthma — the symptoms everyone associates with allergy. In practice that looks like:

• Allergic rhinitis — nasal congestion, sneezing, rhinorrhea, and itch; often the dominant complaint. See our dedicated overview of allergic rhinitis.
• Allergic conjunctivitis — itchy, red, watering eyes that frequently travel with the nasal symptoms.
• Sinus symptoms — chronic or recurrent sinusitis driven by ongoing inflammation and congestion.
• Asthma triggers — aeroallergens including pollen, dust mites, mold, pet dander, and cockroach are well-established asthma provocateurs. Allergy care supports asthma management but does not replace it; see asthma and allergies.

The thread connecting all of these is the histamine-driven inflammatory response. Because the same mediators act across the eyes, nose, sinuses, and airways, a patient often presents with several of these at once — and treating the underlying allergy can quiet the whole cluster.

Testing for environmental allergies

The workhorse test for inhalant allergens is the skin prick test. It is cheap, quick, and gives visible results, and it is most sensitive for environmental allergens — the very allergens this page is about. A small amount of each antigen is introduced into the superficial skin, and the clinician reads the wheal and flare: the central swelling (wheal) and surrounding redness (flare). A response is considered positive when the wheal is at least 3 mm larger than the negative control, with valid positive and negative controls confirming the test.

Skin testing is not for every patient. Candidates with extensive eczema in the test area, dermatographism (a wheal from simple scratching, which makes everything read falsely positive), antihistamine use they cannot stop, or very young age may instead need specific-IgE blood testing (often called RAST), which can screen many antigens from a single draw. Each method has its place; for a side-by-side, see skin testing for allergies and blood testing for allergies. Crucially, neither result is a diagnosis on its own — both must be correlated with the clinical history, and clinicians should avoid the temptation to over-test and fish for incidental positives.

Environmental control and management

Management of environmental allergy is layered. The foundation is allergen avoidance and environmental control — practical, often underused, and the first thing to counsel. Measures track directly to the offending allergen: for dust mites, encasing bedding, reducing carpet and clutter, and controlling humidity; for mold, addressing moisture and damp building conditions; for pet dander, limiting exposure where the patient is willing. When testing turns up only one or two positives — commonly house dust mite or cat — avoidance counseling alone is frequently the right first step.

Avoidance pairs with pharmacotherapy: intranasal corticosteroids and antihistamines remain the mainstays for symptom control, and notably, inhaled or intranasal steroids do not interfere with skin testing, so patients can stay on them during a workup. But avoidance has limits — you cannot wall a patient off from spring pollen — and pharmacotherapy treats symptoms without changing the underlying sensitization. That is where immunotherapy enters.

Where immunotherapy fits

Immunotherapy — what patients call "allergy shots" — is the most rewarding part of allergy care because it is the only approach that modifies the disease rather than masking symptoms. It does not cure allergy, but it durably desensitizes the patient and can transform quality of life for someone with severe seasonal disease. Importantly, immunotherapy works well for environmental allergens specifically; it is not used for food allergies, where avoidance is the rule.

Eligibility hinges on the testing result: subcutaneous immunotherapy (SCIT) is typically appropriate — and insurance-covered — when a patient has three or more positive environmental allergens on skin testing. SCIT proceeds through a build-up phase and then a maintenance phase, with patients observed in-office after each injection given the small risk of a systemic reaction. Sublingual immunotherapy (SLIT) is more convenient because patients dose at home, and FDA-approved SLIT tablets exist for specific allergens — grass, ragweed, and dust mite. Be candid with patients, though: SLIT is generally less effective than shots and often not insurance-covered, and compounded "allergy drops" are largely off-label. For the full picture, see allergy immunotherapy.

The exact build-up and maintenance schedules, dose escalation, cross-reactivity between antigens, and the workflow of partnering with a certified allergy lab are taught in depth in Empire's Allergy Test & Treatment training — this page covers the science and the why, not turnkey protocols.