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Understanding Hay Fever and the IL33 Gene

Hay fever, also called allergic rhinitis, is an immune reaction that causes sneezing, runny nose, nasal congestion, itchy or watery eyes, and sometimes throat irritation. These symptoms occur when the immune system reacts to common environmental allergens such as pollen, pet dander, dust mites, or mold.

The IL33 gene makes interleukin-33, a signaling protein sometimes called an immune "alarmin." When airway cells are stressed by allergens, IL-33 is released and helps activate immune cells that drive type 2 helper T cell, or Th2, responses. Overactivity of this pathway can lead to the inflammation and symptoms associated with hay fever and related conditions like asthma. Variations in the IL33 gene can change how strongly this system responds, influencing an individual’s susceptibility to allergic inflammation.

What Your Genotype Means

Below are easy-to-read interpretations based on the rs928413 variant in IL33. Use the accordion to view the explanation that matches your genotype.

Two effect alleles (GG)

If your genotype is GG, you carry two copies of the effect allele for rs928413. This variant is associated with an increased risk of hay fever and asthma. Mechanistically, the change is linked to heightened IL-33 activity or signaling, which can amplify Th2-type immune responses when the airways encounter allergens like pollen, dust mites, or pet dander.

Practical implications:

  • You may be more likely to experience strong allergic symptoms and inflammation after allergen exposure.
  • Allergen avoidance and early management are especially helpful to reduce episodes and prevent escalation to asthma-like symptoms.
  • Targeted strategies to calm Th2 inflammation and stabilize mast cell responses can reduce symptom frequency and severity.
One effect allele (AG)

If your genotype is AG, you carry one copy of the effect allele. This genotype is associated with a modestly increased risk of hay fever and asthma compared with the baseline population risk. The IL-33 pathway may be somewhat more reactive, which can make allergic inflammation more likely under triggering conditions.

Practical implications:

  • You may notice seasonal or intermittent allergic symptoms, particularly during high-pollen seasons or when exposed to indoor allergens.
  • Combining allergen reduction with supportive lifestyle and nutritional measures can meaningfully reduce symptom burden.
No effect alleles (AA)

If your genotype is AA, you do not carry the G effect allele linked to increased IL33-related risk. Your IL-33 driven allergic risk is within the typical range for the general population. This does not eliminate the possibility of hay fever from other genetic factors or environmental exposures, but it suggests IL33 is not a primary driver of elevated risk in your case.

Practical implications:

  • Standard measures such as allergen avoidance, good nasal hygiene, and targeted nutrients often work well to control symptoms.
  • If symptoms are severe or persistent, further evaluation for other genetic or environmental causes may be helpful.

Diet and Nutrition Strategies

A nutrient-rich diet can support a balanced immune response and reduce overall inflammation that contributes to allergic symptoms.

  • Eat a variety of colorful fruits and vegetables to boost antioxidants and vitamin C. Citrus, berries, kiwi, bell peppers, and leafy greens are particularly helpful.
  • Include omega-3 rich foods such as fatty fish, chia seeds, flaxseed, and walnuts to support anti-inflammatory pathways.
  • Increase natural quercetin-containing foods like onions, apples, capers, and berries. Quercetin is a plant flavonoid known to stabilize mast cells and reduce histamine release.
  • Choose fermented foods like yogurt, kefir, sauerkraut, kimchi, and miso to support gut microbial balance, which is linked to immune regulation.
  • Limit highly processed foods, excess added sugars, and trans fats that can promote systemic inflammation.

Supplement Considerations

Supplements can complement diet and lifestyle when used appropriately. Discuss these options with your healthcare provider.

  • Vitamin C: A natural antioxidant that may reduce histamine levels and support immune health. Typical supplemental doses range from 250 to 1,000 mg daily depending on needs.
  • Quercetin: A bioflavonoid that helps stabilize mast cells and may reduce allergic symptoms. Common supplemental doses are 250 to 500 mg two to three times daily with meals.
  • Probiotics: Strains such as Lactobacillus and Bifidobacterium can support a healthier gut-immune axis. Choose a well-characterized product with adequate colony-forming units (CFUs) and strain information.
  • Omega-3 fatty acids (EPA/DHA): Fish oil supplements can help reduce inflammation; typical ranges are 500 to 1,000 mg combined EPA/DHA daily for maintenance.
  • Vitamin D: Supports immune regulation. Check blood levels before supplementing; many benefit from moderate supplementation if levels are low.

Lifestyle and Environmental Tips

  • Allergen avoidance: Close windows during high-pollen times, use HEPA filters or air purifiers, and keep indoor humidity between 30 and 50 percent to reduce dust mites and mold.
  • Nasal hygiene: Saline nasal rinses or sprays help remove allergens and reduce nasal inflammation.
  • Pet management: If pet dander triggers symptoms, restrict pets from bedrooms and wash hands after stroking animals. Regular bathing of pets can reduce dander.
  • Cleaning routine: Frequent vacuuming with a HEPA-filter vacuum and washing bedding in hot water weekly reduce indoor allergen load.
  • Exercise: Regular moderate exercise supports immune balance and respiratory health, but avoid outdoor workouts during peak pollen counts.
  • Hydration and sleep: Adequate fluids and good sleep support immune resilience and recovery from inflammatory episodes.

When to Seek Additional Testing or Care

  • If symptoms are severe, persistent, or interfering with daily life, consult a healthcare professional for evaluation and treatment options.
  • Allergy testing may identify specific allergens to target avoidance or immunotherapy.
  • Work with your provider to review medication choices, including antihistamines, intranasal corticosteroids, or other prescribed therapies when needed.

Important Disclaimer

PlexusDx provides educational information about genetic predispositions only. This content is not medical advice. Always consult your healthcare provider before starting, stopping, or changing diet, supplements, medications, or lifestyle practices based on genetic information.