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Pollen allergies are a significant global health concern, especially as climate change increases the geographical spread and length of exposure to allergenic pollen. Approximately 40% of Europeans are sensitised to pollen allergens. While early bloomers like hazel and alder cause discomfort at the start of the year, many plants continue to release pollen throughout spring and summer. Notably, plants in the Oleaceae family, such as olive, ash, privet, and lavender, are major contributors, especially in regions with mild climates. These plants frequently show high cross-reactivity with other allergens, which can worsen symptoms in individuals already sensitive to other types of pollen.
Symptoms
Symptoms primarily affect areas directly exposed to pollen allergens, such as the mucous membranes of the nose, eyes, and mouth. The associated symptoms may include sneezing, nasal congestion, runny nose, watery eyes, itchy throat and eyes, and wheezing. Apart from the classical pollen allergy symptoms, pollen allergies may also cause sleep disorders, fatigue, depression, and impaired cognition in allergic patients.
Olive
Olive pollen is a major allergen in Mediterranean and other warm climates, peaking from mid-April to late June. In Spain, olive pollen rank as the second most prevalent cause of allergy after grasses. Ole e 1, which belongs to the Ole e 1 Family, shows strong cross-reactivity with other members of the Oleaceae family, including Fra e 1 (ash), Lig v 1 (privet), and Syr v 1 (lilac). Due to its extraordinary cross-reactivity with ash, Ole e 1 is a recognised marker allergen for diagnosing European ash pollen allergy.
Ash
European ash is a potent allergen source, which is widely distributed across temperate regions. The major allergen is Fra e 1, an Ole e 1-like protein family member, which is structurally similar to olive pollen. Ash pollen sensitisation has been underestimated due to its overlap with birch pollination. Recent studies suggest it plays a more significant role in pollen allergies, accounting for 18-34% of cases. Released in late spring, ash pollen extends allergy seasons and worsens symptoms in individuals already affected by olive pollen.
Privet & Lilac
Though primarily insect-pollinated and not major airborne allergens, privet and lilac are clinically relevant for allergy sufferers due to their high cross-reactivity with other Oleaceae family members, especially olive and ash.
Privet flowers from late spring to early summer, with Lig v 1, an Ole e 1-like protein, being the main allergen.
Lilac flowers from April to June, sharing significant cross-reactivity with olive, ash, and privet through allergens like Syr v 1, an Ole e 1-like protein.
Diagnosis
If a pollen allergy is suspected, it’s advisable to consult a doctor for confirmation. Various tests, including skin prick tests and blood tests, can provide valuable insights. The ALEX² allergy test offers a comprehensive panel of allergens, helping to ensure an accurate diagnosis.
Prevention and therapy
Fortunately, there are multiple treatment approaches to help manage pollen allergies. Doctors may prescribe symptomatic relief in the form of antihistamine tablets, nasal sprays, or eye drops. Using pollen calendars can help assess allergy risks and guide patients to take precautions during high pollen periods. Planning outdoor activities when pollen levels are lower can also reduce exposure and ease symptoms. Allergen-specific immunotherapy (AIT) is a long-term treatment option for pollen allergies. Since many patients with tree pollen allergies are also sensitised to other allergens, identifying the primary trigger is key for effective treatment, ensuring the best results with targeted AIT.
Conclusion
If you experience persistent allergy symptoms during spring and summer, it may be time to consult an allergy specialist to determine the best course of action. With the right management strategies, you can still enjoy the beauty of spring without the discomfort of allergies.
References
- Eder, K., et al., Component resolved analysis of ash pollen allergy in Bavaria. Allergy Asthma Clin Immunol, 2018. 14: p. 76.
- Imhof, K., et al., Ash pollen allergy: reliable detection of sensitization on the basis of IgE to Ole e 1. Allergo J Int, 2014. 23(3): p. 78-83.
- Kalmarzi, R., et al., The impact of allergic rhinitis on quality of life: a study in western Iran. Biomedpress, 2017. 4(9): p. 1629-1637.
- Tamm, S., et al., Evidence of fatigue, disordered sleep and peripheral inflammation, but not increased brain TSPO expression, in seasonal allergy: A [(11)C]PBR28 PET study. Brain Behav Immun, 2018. 68: p. 146-157.
- Villalba, M., R. Rodriguez, and E. Batanero, The spectrum of olive pollen allergens. From structures to diagnosis and treatment. Methods, 2014. 66(1): p. 44-54.
- NC State University, Ligustrum lucidum; [cited 2025 Mar 25]. Available from: https://plants.ces.ncsu.edu/plants/ligustrum-lucidum/
- Recorded Pollen and Mold Information. In 2012. [cited 2025 Mar 25]. https://pollenandmold.stlouisco.com/html/AshLilacPrivetOlive.html
- European Centre for Allergy Research Foundation, Pollen Allergy. In 2016. [cited 2025 Mar 25]. https://www.ecarf.org/en/information-portal/allergies-overview/pollen-allergy/