3 supplements for allergies: what the research actually shows

Allergic rhinitis affects roughly 10-30% of adults and nearly 40% of children worldwide [1]. In the United States alone, around 60 million people deal with seasonal allergies each year [2]. The symptoms are familiar to anyone who’s suffered through pollen season: sneezing, runny nose, itchy eyes, congestion, and the general feeling that your immune system has decided to wage war against tree pollen.

Standard treatment involves antihistamines, nasal corticosteroids, and avoiding allergens when possible. But many people wonder whether dietary supplements might help reduce symptoms or decrease reliance on medications. I’ve gone through the clinical research on three supplements that have been studied for allergic rhinitis: probiotics, fish oil (omega-3 fatty acids), and vitamin D.

The short answer? There’s some evidence for each, but it’s not overwhelming. Let me walk through what we actually know.

Understanding allergic rhinitis

Before diving into supplements, it helps to understand what allergic rhinitis actually is. When you have allergies, your immune system treats harmless substances like pollen, dust mites, or pet dander as threats. It produces IgE antibodies that trigger the release of histamine and other inflammatory chemicals. This cascade causes the classic symptoms: sneezing, itching, congestion, and watery eyes.

Allergic rhinitis comes in two forms. Seasonal allergic rhinitis (hay fever) occurs during specific times of year when particular pollens are present. Perennial allergic rhinitis persists year-round, typically triggered by indoor allergens like dust mites, mould, or pet dander.

The condition isn’t just annoying. It affects sleep quality, work productivity, and general wellbeing. Studies consistently show that people with allergic rhinitis have reduced quality of life, particularly during symptom flare-ups [3]. So looking for additional approaches beyond standard medications makes sense.

1. Probiotics

This is probably the supplement with the most research attention for allergies, and the results are genuinely interesting.

What are probiotics?

Probiotics are live microorganisms, primarily bacteria, that may provide health benefits when consumed in adequate amounts. The human gut contains trillions of bacteria, and this gut microbiome appears to influence immune function in ways researchers are still working to understand.

The connection between gut bacteria and allergies isn’t as strange as it might sound. A significant portion of the immune system is associated with the gut, and the bacteria living there interact with immune cells in complex ways. The “hygiene hypothesis” suggests that modern clean environments and antibiotic use may alter gut bacteria in ways that increase allergy risk.

What does the research show?

A systematic review and meta-analysis examined multiple trials of probiotics for allergic rhinitis [4]. The analysis found that probiotics provided modest but statistically significant improvements in nasal symptoms and quality of life compared to placebo.

Specific strains matter. Lactobacillus paracasei (LP-33) has been studied most extensively and shows consistent benefits in several trials. Other strains like Lactobacillus acidophilus, Lactobacillus rhamnosus, and Bifidobacterium species have also shown promise.

One randomised controlled trial gave 425 patients with seasonal allergic rhinitis either a probiotic combination or placebo for five weeks during grass pollen season [5]. The probiotic group showed improved quality of life scores and reduced use of rescue antihistamines compared to placebo.

The mechanism appears to involve shifting the balance between different types of immune cells (specifically the Th1/Th2 ratio), which may reduce the allergic response.

My honest assessment

The evidence here is better than I expected going in. Multiple trials show modest benefits, and the safety profile is excellent. The effects aren’t dramatic; nobody’s going to throw away their antihistamines after taking probiotics. But as an add-on treatment, probiotics seem reasonable.

The catch? Studies use different strains at different doses, making it hard to recommend a specific product. LP-33 strains have the most evidence. Cost is also a factor; quality probiotic supplements aren’t cheap.

For more detailed information on probiotics, including their other potential benefits and safety considerations, see our comprehensive guide to probiotics benefits and side effects.

2. Fish oil (omega-3 fatty acids)

Omega-3 fatty acids have anti-inflammatory properties, which makes them theoretically attractive for allergies. But theory and reality don’t always align.

Understanding omega-3s

Fish oil contains two main omega-3 fatty acids: EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid). These compete with omega-6 fatty acids (which are more pro-inflammatory) in various metabolic pathways. The idea is that increasing omega-3 intake might shift the body toward a less inflammatory state.

Plant sources provide ALA (alpha-linolenic acid), which the body can convert to EPA and DHA. However, conversion rates are poor, typically under 10%, so fish or algae-derived supplements are more efficient sources [6].

What does the research show?

A cross-sectional study of 568 adults found that higher dietary intake of omega-3 fatty acids (both EPA and ALA) was associated with lower rates of allergic sensitisation and allergic rhinitis [7]. People who ate more omega-3-rich foods had fewer allergies.

However, cross-sectional studies can’t prove causation. People who eat more fish might differ in other ways from those who don’t.

Intervention trials, where researchers actually give omega-3 supplements to people and measure outcomes, show mixed results. Some studies report modest improvements in symptoms; others find no benefit. A Cochrane review on fish oil for asthma (a related allergic condition) concluded the evidence was insufficient to recommend fish oil supplements [8].

My honest assessment

The epidemiological data is intriguing. People with higher omega-3 intake do seem to have fewer allergies. But when it comes to treating existing allergic rhinitis with supplements, the evidence is weaker than for probiotics.

I wouldn’t take fish oil specifically for allergies, but omega-3s have other potential benefits for cardiovascular health, so they’re not unreasonable supplements for other reasons. If you’re already taking fish oil, there might be a modest bonus for allergy symptoms, but don’t expect much.

3. Vitamin D

This is the supplement that surprised me most when reviewing the research. Vitamin D deficiency is remarkably common, and its connection to allergies is more substantial than I initially assumed.

The vitamin D deficiency problem

About half the global population has insufficient vitamin D levels [9]. This is partly because modern lifestyles involve less sun exposure and vitamin D-rich foods aren’t a major part of most diets. Factors like darker skin, living at higher latitudes, ageing, and regular sunscreen use all reduce vitamin D synthesis.

Vitamin D is primarily known for bone health, but receptors for vitamin D are found throughout the immune system. Vitamin D influences how immune cells develop and respond to stimuli.

The allergy connection

Several observational studies have found associations between low vitamin D levels and higher rates of allergic disease. One study found that vitamin D deficiency was more common in people with allergic rhinitis compared to controls [10].

The mechanism may involve vitamin D’s effects on regulatory T cells, which help keep immune responses from overreacting. Vitamin D also influences the gut barrier and the microbiome, which links back to the probiotic story.

What does the research show?

A randomised controlled trial gave vitamin D or placebo to patients with allergic rhinitis for eight weeks [11]. The vitamin D group showed significant improvement in nasal symptoms compared to placebo. Another study found that vitamin D supplementation reduced allergic rhinitis symptoms and improved quality of life scores.

A meta-analysis examining vitamin D supplementation for allergic rhinitis concluded there was a significant reduction in symptoms with treatment [12]. The effect sizes were moderate, not massive, but consistently favoured vitamin D over placebo.

My honest assessment

If you have allergic rhinitis and low or borderline vitamin D levels (which is likely given how common deficiency is), supplementing vitamin D seems reasonable. The research is more consistent than I expected.

The practical issue is knowing your vitamin D status. A blood test can measure 25-hydroxyvitamin D levels. Levels below 30 ng/mL are generally considered insufficient, and below 20 ng/mL is deficient.

For a complete overview of vitamin D’s benefits and safety considerations, see our vitamin D guide.

Other supplements sometimes mentioned

A few other supplements appear in allergy discussions:

Quercetin is a plant flavonoid with antihistamine properties in test-tube studies. Some people swear by it, but human clinical trials are limited. It might help, but the evidence base is thin compared to the three supplements above. See our quercetin article for more details.

Black seed (Nigella sativa) has traditional use for allergies and some clinical trial support. One study found it improved nasal symptoms in allergic rhinitis [13]. It’s worth considering if you’re interested in herbal approaches. More information is available in our black seeds guide.

Butterbur has shown benefit for hay fever in some trials, but hepatotoxicity concerns with certain preparations limit enthusiasm.

Practical recommendations

Based on my review of the evidence, here’s what I’d suggest:

Get your vitamin D tested. If levels are low (which is probable), supplementing makes sense for multiple reasons, including potential allergy benefits. The NHS recommends 10 micrograms (400 IU) daily for adults during autumn and winter, though higher doses may be appropriate if deficient [14].

Consider probiotics as an add-on. The evidence is decent, safety is excellent, and they’re unlikely to interact with standard allergy medications. Look for products containing well-studied strains like Lactobacillus paracasei.

Don’t rely on supplements alone. These are adjuncts, not replacements for standard treatment. Antihistamines, nasal corticosteroids, and allergen avoidance remain the foundation of allergy management.

Be patient. Unlike antihistamines that work within hours, supplements typically need weeks of consistent use before any benefits appear. Studies usually run for 4-8 weeks minimum.

What won’t help

I should mention some things that don’t have good evidence:

Local honey for allergies is popular folk wisdom, but clinical trials don’t support it. The amount of pollen in honey is trivial, and the types differ from airborne pollens causing hay fever.

High-dose vitamin C is often recommended, but evidence for allergic rhinitis is weak. It might have slight antihistamine effects, but nothing dramatic.

Most “immune boosting” supplements are marketing more than science.

The bottom line

For allergic rhinitis, probiotics and vitamin D have the most consistent evidence among dietary supplements. Fish oil’s benefits are less clear for allergies specifically, though it may have other health benefits.

None of these supplements are miracle cures. The effects in studies are modest. But for people looking to optimise their approach to allergy management, they’re reasonable considerations, particularly vitamin D if you’re among the many people with insufficient levels.

As with any supplement, discuss with your doctor if you’re taking other medications or have underlying health conditions. And remember that the foundation of allergy management remains avoiding triggers where possible and using proven medications when needed.

Related reading

• Probiotics: 32 benefits, side effects, and contraindications
• Fish oil: 28 benefits, side effects, and contraindications
• Vitamin D: comprehensive benefits and safety guide

References

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2. American College of Allergy, Asthma & Immunology. Allergic Rhinitis. https://acaai.org/allergies/allergic-conditions/allergic-rhinitis/
3. Meltzer EO. Quality of life in adults and children with allergic rhinitis. J Allergy Clin Immunol. 2001;108(1 Suppl):S45-53.
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14. NHS. Vitamin D. https://www.nhs.uk/conditions/vitamins-and-minerals/vitamin-d/