Spring is about to be sprung, and it’s that time of year again when pollen levels begin to rise and many people experience seasonal allergies. One in four people in the UK (approximately 16 million) suffer from allergic rhinitis (hay fever) and up to 49% of the population report experiencing hay fever symptoms on occasion. Many of these will reach for over the counter (OTC) medications which can cause an array of side effects, therefore considering natural antihistamines can be a desirable alternative. In this blog we look at the mechanisms behind allergy and nutrients that act as natural antihistamines to reduce symptoms of seasonal allergies.
Firstly, let’s do a brief introduction to the allergic response
What happens during an allergy?
- An allergen, (in the case of hay fever, pollen), enters the body via the skin, respiratory tract or gastrointestinal tract, which are lined with epithelial cells. If the epithelial lining is compromised, then allergens are able to translocate across the lining, triggering the immune system.
- Allergens are detected by antigen presenting cells, which they present to T helper cells and then, in turn, antibody producing B cells (producing IgE antibodies in response). This creates antibodies against pollen, initiating a more rapid and intense response to pollen upon the next exposure.
- Pollen then binds with the antibody IgE, which activates receptors on mast cells (part of the innate immune system), prompting further immune response and releasing histamine.
- Mast cells induce a further inflammatory response, initiating the production of chemical mediators such as proinflammatory cytokines and leukotrienes.
- Other immune cells are recruited, including Th2 lymphocytes, eosinophils and basophils (Guryanova, 2022).
Both mast cells and basophils produce the chemical histamine, which is often a target of anti-allergic therapy such as OTC medications (antihistamines). Histamine is part of the immediate reaction to an allergen and therefore medications target histamine as they can quickly reduce symptoms.
When it is released, histamine induces vasodilation and increases vascular permeability, which allows an increase of fluid into blood vessels leading to swelling and irritation. It also increases heart rate, cardiac contraction and glandular secretion, all of which, when in combination with other immune activation, have the potential to induce anaphylactic shock, which can be fatal. However, in most people it will lead to symptoms associated with hay fever, including sneezing, itching and watering eyes and nose (Branco, 2018).
Nutritional support for allergy
Attenuating excess histamine is helpful when supporting individuals with allergies (we discuss this below). However, as can be seen above, allergy development involves disruption to epithelial (including gut) integrity and immune function leading to excess inflammation. Supporting these primarily is essential for building resilience to allergy and maintaining long-term immune function.
- Immune function – vitamin C, vitamin D3, N-acetyl cysteine (NAC)
- Microbiome – live bacteria supplements and prebiotic fibre
- Epithelial integrity- vitamin A, vitamin D3, zinc, glutamine, lactoferrin
- Mucosal tissue – NAC, marshmallow, slippery elm
- Reduce inflammation – curcumin, ginger, omega 3 fatty acids, quercetin (Murray, 2013)
Also – don’t forget antioxidants e.g. vitamins A, C and E. These help to protect against and repair damage, especially to the epithelium, and by doing so attenuate inflammation. Some antioxidants also have antihistamine properties so can have a cumulative effect, such as vitamin C and quercetin (below).
Natural antihistamines
In addition to the above support, natural antihistamines can be a great way to manage hay fever symptoms. These include:
Vitamin C has been widely discussed as an important anti-allergy nutrient. It has antioxidant properties (Bendich, 1986) and hence attenuates epithelial damage and therefore sensitisation (Carr, 2017).
Vitamin C contributes to the normal function of the immune system, and it is reported to have natural antihistamine properties by breaking down the molecular structure of histamine (co-factor for histamine N-methyltransferase), therefore decreasing its volume in the blood. It can improve symptoms of allergic rhinitis including itching and sneezing (Ghalibaf 2023
Vitamin C also supports the absorption of quercetin (Ghalibaf, 2023).
Quercetin is a potent antioxidant and also promotes a healthy inflammatory response. Quercetin counteracts the allergic response by suppressing IgE antibody formation, thereby acting at a very early step in the development of allergy. It inhibits the release of histamine and proinflammatory substances. Quercetin also has membrane stabilising properties and can have an anti-inflammatory effect on the mucous membranes. (Mlcek, 2016)
Clinical studies show that quercetin reduces symptoms associated with allergic rhinitis including itching, sneezing, nasal discharge, and sleep disorders and improves quality of life scores (Yamada, 2022).
Beta 1-3, 1-6 Glucan is best known for its immune supporting properties, with extensive research indicating it may optimise the function of the immune system. Put simply, Beta 1-3, 1-6 Glucan ‘primes’ the immune system, alerting the body to help defend itself against foreign invaders (Akramiene, 2007).
In terms of allergies, Beta 1-3, 1-6 Glucan is capable of binding to receptors on the surface of innate immune cells, and this action is suggested as playing a role in reducing the symptoms caused by IgE production, especially histamine release. Beta Glucan ‘down-regulates’ sensitivity and immune over reaction, as seen in allergies (Talbott, 2013).
Supplementation with beta glucan for 4 weeks improves allergy symptoms, overall physical health, and emotional well-being compared with placebo (Talbott, 2014).
Luteolin attenuates allergic nasal inflammation via inhibition of IL-4 production, stabilises mast cells and improves allergy symptoms. (Kritas, 2013). It is being considered as a potential pharmaceutical application for allergic rhinitis treatment (Liang, 2020).
Bromelain is a proteolytic (and mucolytic) enzyme derived from pineapple stems that acts as a natural antihistamine and anti-inflammatory agent. It is frequently used to treat nasal congestion, sinusitis, and respiratory distress associated with allergies by reducing inflammation, breaking down mucus, and modulating the immune system. It has been shown to be particularly useful for nasal inflammation (Alves Nobre, 2025).
Spirulina is a blue-green algae and a nutritional powerhouse, providing protein, vitamins, minerals, essential and non-essential amino acids, fatty acids, trace elements and the carotenoids beta carotene, beta cryptoxanthin and zeaxanthin.
In the support of allergies, spirulina has been shown to relieve inflammation in the nasal cavity as well as decreasing histamine levels, thereby reducing itching, nasal discharge, nasal congestion, and sneezing. The main mechanism appears to be by supressing the differentiation of Th2 cells and IgE production (Gromek,2024). One study demonstrated that spirulina was more effective than the antihistamine medication cetirizine at improving the symptoms of allergic rhinitis (Cingi, 2008).
It is important to note that spirulina has a plethora of support for attenuating histamine and allergic responses. However, in some sensitive individuals it has been documented that it may trigger allergic symptoms via IgE activation, these reports are rare and seem to be for poor quality spirulina products (Gromek, 2024). However, if an individual is very sensitive it is recommended to start with a small dose to test individual tolerance.
The above interventions can be very useful when supporting those with seasonal allergies, however it is best to start a couple of months before symptoms begin to help build resilience and immune tolerance. Hence this is a perfect time of year to begin!
Key takeaways
- Seasonal allergies (also known as allergic rhinitis or hay fever), are symptoms of immune dysregulation, initially triggered by sensitisation of the respiratory epithelium leading to a cascade of immune activation and production of histamine.
- Histamine is a chemical mediator released by basophils and mast cells (part of the immune system) in response to an allergen. It causes vasodilation and increases vascular permeability, which allows an increase of fluid into blood vessels leading to swelling and irritation. This leads to symptoms associated with hay fever, such as sneezing, itching, watery eyes and nose, associated with hay fever.
- Natural antihistamines are useful for ameliorating symptoms of hay fever, these include vitamin C, quercetin, luteolin, bromelain, beta glucans and spirulina.
- Additionally supporting a healthy immune response, epithelial integrity and a healthy balance microbiome are effective long-term interventions for supporting resilience to allergy. Therefore, live bacteria supplements, immune supporting nutrients (e.g. vitamin D, N-acetyl cysteine and vitamin C), nutrients that support the integrity of the gut and respiratory epithelium (glutamine, vitamin A and zinc) and reducing inflammation (curcumin, ginger and quercetin) are helpful interventions.
References
Akramiene, D., Kondrotas, A., et al. (2007). Effects of beta-glucans on the immune system. In Medicina (Kaunas, Lithuania) (Vol. 43, Number 8, pp. 597–606).
Alves Nobre, T., de Sousa, A. A., et al.(2025). Bromelain as a natural anti-inflammatory drug: a systematic review. Natural Product Research, 39(5), 1258–1271.
Bendich, A., Machlin, L. J., et al. (1986). The antioxidant role of vitamin C. Advances in Free Radical Biology and Medicine, 2(2), 419–444.
Branco, A. C. C. C., Yoshikawa, et al. (2018). Role of Histamine in Modulating the Immune Response and Inflammation. Mediators of Inflammation, 2018.
Carr, A. C., & Maggini, S. (2017). Vitamin C and Immune Function. Nutrients, 9(11).
Cingi, C., Conk-Dalay, et al.(2008). The effects of spirulina on allergic rhinitis. European Archives of Oto-Rhino-Laryngology : Official Journal of the European Federation of Oto-Rhino-Laryngological Societies (EUFOS) : Affiliated with the German Society for Oto-Rhino-Laryngology – Head and Neck Surgery, 265(10), 1219–1223.
Ghalibaf, M. H. E., Kianian, F., et al. (2023a). The effects of vitamin C on respiratory, allergic and immunological diseases: an experimental and clinical-based review. Inflammopharmacology, 31(2), 653.
Gromek, W., Kołdej, N., et al.(2024). Spirulina (Arthrospira platensis): Antiallergic Agent or Hidden Allergen? A Literature Review. Foods, 13(7), 1052.
Guryanova, S. V., Finkina, E. I., et al. (2022). How Do Pollen Allergens Sensitize? Frontiers in Molecular Biosciences, 9, 900533.
Liang, K. L., Yu, S. J., et al.2020). Luteolin Attenuates Allergic Nasal Inflammation via Inhibition of Interleukin-4 in an Allergic Rhinitis Mouse Model and Peripheral Blood From Human Subjects With Allergic Rhinitis. Frontiers in Pharmacology, 11, 291.
Mlcek, J., Jurikova, T., et al. (2016). Quercetin and Its Anti-Allergic Immune Response. Molecules (Basel, Switzerland), 21(5). Murray, J. Pizzorno. M. (2013). Textbook of Natural Medicine (4th Ed).
Talbott, S. M., Talbott, J. A., et al. (2013). β‐Glucan supplementation, allergy symptoms, and quality of life in self‐described ragweed allergy sufferers. Food Science & Nutrition, 1(1), 90.
Yamada, S., Shirai, M., et al. (2022). Effects of repeated oral intake of a quercetin-containing supplement on allergic reaction: a randomized, placebo-controlled, double-blind parallel-group study. European Review for Medical and Pharmacological Sciences, 26(12), 4331–4345.
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Last updated on 4th March 2026 by cytoffice
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