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Summer Allergies in a Changing Climate

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Anyone with seasonal pollen allergies to grasses greets the summer season with sneezing, itching, watery eyes, and other symptoms. Some may develop asthma exacerbations or seasonal gastrointestinal symptoms due to inhaled and swallowed pollens in the gut. In August, the autumn pollens from ragweed and mugwort make their debut and even more individuals will experience seasonal symptoms.

Seasonal hypersensitivity symptoms can result in significant health burdens from lost work or school days and increased healthcare costs. Pollen-related health burdens are likely to increase, not decrease, as our changing climate alters the start, duration, and intensity of pollen seasons. A multi-year study of North American plants and pollen distributions found that pollen seasons may be longer in higher northern latitudes by as much as four weeks. We are seeing real-time evidence of this as cities in Siberia recorded 100-degree temperatures during June 2020 for the first time in recorded history.

The Different Types of Aeroallergen Reactions

Pollen reactions happen when the body’s immune system over-reacts to the presence of harmless substances such as pollens or foods. Pollen-related symptoms may be driven by either IgE or IgG immune responses. Since both IgE and IgG levels may rise with pollen or other aeroallergen exposures, the testing selected should be determined by the patient’s reaction to the antigen. More immediate reactions (minutes to hours after exposures) indicate type I hypersensitivity, while chronic inflammatory symptoms are associated with IgG reactions.


IgE reactions result in type I hypersensitivity, the type of immediate reaction that may result in anaphylaxis. IgG4 is a blocking antibody for IgE, and it helps protect against anaphylactic reactions. The other three IgG subclasses (IgG1, IgG2, IgG3) result in delayed hypersensitivity reactions, which can occur up to 72 hours after an exposure. IgG1,2,3 all cause more chronic inflammation by activating the complement system. It can be difficult to determine the trigger with IgG reactions due to the delay in symptom presentation, without testing.

Aeroallergens and Food Cross-Reactivities

Pollen exposures can also promote cross-reactions with commonly eaten foods, because there are common proteins found in the pollens that are shared with other types of fruit and vegetable plants. These cross-reactions can exacerbate food sensitivity reactions during pollen season. Common pollen-food cross-reactions are listed in the chart below:


Season Aeroallergen Food Cross-Reactions
Spring (March - Mid-May)

Birch (Betula) Pollen

Almonds, Apples, Carrots, Celery, Cherries, Coriander, Fennel, Hazelnuts, Kiwi, Parsley, Peaches, Pears, Plums, Raw potato

Summer (Mid-May - July)

Grasses (Poaceae spp.)

Celery, Cantaloupe, Oranges, Peaches, Tomatoes, Watermelon, Grains (possibly)

Fall (August - November)

Ragweed (Ambrosia spp.) Pollen

Banana, Cantaloupe Melon, Chamomile , Echinacea, Honeydew Melon, Sunflower Seeds, Tomatoes, Watermelon, Zucchini

Mugwort (Artemisia vulgaris) Pollen

Apples, Carrots, Celery, Kiwi, Peanuts, Anise Seeds, Caraway Seeds, Coriander, Fennel Seeds, Parsley


Indoor Allergies; Dust Mites

Shrimp, Clam, Crab, Lobster, Oyster

On-Demand Webinar: When Food Allergies and the Environment Collide

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5 Steps to Help Patients Through Pollen Season

Clinicians may employ a series of steps to manage both food sensitivity and inhalant allergies and provide patient relief:


1. Evaluate Hypersensitivity

2. Serum testing for IgE/IgG4 for aeroallergens and suspected Type I (immediate) food allergens.

3. Improve diet:

  • Eliminate processed foods, trans-fats and known IgE food allergens
  • Eliminate and rotate foods per IgG results to reduce the likelihood of food sensitization
  • Increase fruit and vegetable consumption
  • Evaluate digestion, gastric pH and the gastrointestinal microbiome and treat per results

4. Monitor, manage, or eliminate aeroallergen exposures:

  • Monitor pollen counts and air pollution levels if there are seasonal exacerbations or comorbid seasonal inhalant allergies.
    • Keep doors and windows closed when counts are high, stay indoors and use air-conditioning, etc.
  • Identify and eliminate environmental mold exposures that may contribute to antigen sensitization and inflammation. Epidemiologic studies in the United States and Europe have associated mold sensitivity, particularly to Alternaria alternata and Cladosporium herbarum, with the development, persistence, and severity of asthma.
  • Reduce dust mite exposures
    • Wash bedding weekly in hot water
    • Vacuum frequently
    • Do not sleep with pets if dander is a problem, and keep pets out of bedrooms.

5. Use anti-inflammatory therapies to modulate the immune system.

  • Stabilize mast cells with
  • Andrographis paniculata (green chiretta)
  • Vitamins A, C, D, E, B6
  • Flavonoids (quercetin, luteolin)
  • Herbs
    • Ammi visnaga (khella)
    • Astragalus membranaceus, Astragalus mongholicus
    • Cordyceps (Ophiocordyceps sinensis)
    • Petasites hybridus (butterbur)
      • Use preparation free of pyrrolizidine alkaloids
    • Urtica dioca (stinging nettles)
    • Spirulina
    • Quercetin

In conclusion, summer aeroallergen woes may be exacerbated by food sensitivities, food-pollen cross-reactions or indoor aeroallergens. A variety of management strategies may be employed to provide relief for patients during the summer allergy season.




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