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Allergies are caused by a stressor, or antigen, overstimulating the body’s immune system resulting in unwanted reactions. Evidence supports the use of some supplements to generally suppress this response and reduce the body’s reaction. Genetics and the environment both play a role in the development of allergic diseases, such as food allergies.

Our evidence-based analysis on allergies features 34 unique references to scientific papers.

Research analysis led by and reviewed by the Examine team.
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Summary of Allergies

Overview | Causes | Symptoms | Diagnosis | Treatments


Allergies are common and chronic conditions that are intertwined with immune system function.[1] The immune system is the body’s defense network, which normally fights off unwanted invaders like viruses, bacteria, and other infectious agents. During most allergic reactions, the immune system is responding to a false alarm and treats a generally harmless substance, like pollen, as a threat.

There are different types of allergies, including asthma, atopic dermatitis, allergic rhinitis, and food allergies, but it is not uncommon for people who have allergies to be sensitive to more than one stressor.


The causes of allergies are complex, as both genetics and environmental factors contribute to their development. If you have a family history of allergies, you have an increased risk of developing allergies, but that does not mean you will develop them.

Allergic reactions can be caused by:

  1. Contact (foods, latex, poisonous plants)

  2. Injection (insect bites and stings)

  3. Ingestion (drugs, foods, supplements)

  4. Inhalation (dust, mold, pet dander, smoke, pollen)


Allergies can manifest in many ways, including asthma, itching, rashes, runny nose, sneezing, and swelling, and in varying degrees of severity, from mild irritation to anaphylaxis — a life-threatening reaction requiring immediate medical treatment.

The way allergies manifest depends on the exposure pathway, as shown below.

Differences in allergy exposure route and symptoms


Skin exposure: hives, rash, itching, blistering
Eye and mouth exposure: redness, swelling, itching, tearing up of eyes


Symptoms can vary widely, depending on the insect. Reactions can range from redness, general pain, swelling, and itching, to severe chest pain, throat swelling, and rash.


Food exposure: Upset stomach, diarrhea, nausea, vomiting, metallic taste, coughing, wheezing, nasal congestion, trouble breathing, hives, tingling, itching, redness.

Drug or supplement exposure: Symptoms can vary widely, but typically involve the whole body, resulting in chills, aches, nausea, etc.


Sinus irritation, stuffiness, itching, cough, mucus.


Blood test

When the immune system perceives a threat, it produces antibodies called immunoglobulin E (IgE). A blood test can measure the amount of IgE antibodies present in the body. A small amount is normal, but a large amount can indicate an allergy.

Two types of IgE blood tests are commonly used: total and specific.

  • High total IgE levels can indicate you have an allergy.

  • The specific IgE test helps identify the specific allergen you are sensitive to.

Sometimes a complete blood count (CBC) test is used to measure eosinophil white blood cell levels. Eosinophil levels, which are normally under 500 cells per microliter (cells/mcL), can be elevated if you have allergies.

Skin test

An allergy skin test (scratch, skin prick, or patch test) is used to determine which specific allergens are causing an allergic reaction. The test involves exposing skin to the specific allergen using one of these methods:

  • Scratch/prick test, in which a liquid drop containing the allergen is placed on the skin. A light scratch or prick through each drop is administered to better expose the body to the allergen.

  • Intradermal test, in which a small amount of the allergen is injected just below the surface of the skin.

  • Patch test, in which an adhesive patch is worn on the skin for 48–96 hours, after which the medical provider removes the patch and checks for rashes and reactions.

An allergy to the tested substance may exist if the site of the skin test becomes red or swells during any of the above tests. The larger the reaction, the more likely there is an allergy. Commonly tested allergens include pollen, dust, molds, and some drugs. Food allergies are typically not diagnosed with skin tests, as they are more likely to cause anaphylactic shock.

Oral food challenge

Oral food challenges (OFCs) can be used to confirm the presence of a specific food allergy or to determine whether the allergy has resolved. The test involves eliminating the foods being tested from the diet for a period of time, followed by a medically supervised refeeding of the eliminated foods.

There are three main types of OFCs:

  • Open, in which both the participant and observer know what food is being tested.

  • Single-blind, in which only the observer knows what food is being tested. In these trials, the tested food may be concealed in a capsule and a placebo capsule may or may not be used as a control.

  • Double-blind and placebo-controlled, the gold-standard in food allergy diagnostics, in which both the participant and observer are blinded to the food being tested. At least two feedings occur and neither party knows which food is being tested in which feeding.

Unproven tests and misdiagnosis

Mail-order lab tests that can be shipped right to your door which claim to help you identify food allergies (i.e. causes an immune reaction) and intolerances (i.e. causes a digestive reaction) have become increasingly popular. However, many such tests rely on an unproven method — IgG blood tests, not to be confused with IgE blood tests, discussed above.

The Canadian Society of Allergy and Clinical Immunology (CSACI),[2] the European Academy of Allergy and Clinical Immunology (EAACI),[3], the National Institute of Allergy and Infectious Diseases (NIAID),[4] and the American Academy of Allergy, Asthma & Immunology (AAAI)[5] recommend against such tests, as they have not been shown to reliably or accurately identify food allergies or intolerances.[6]

Caution is also advised for the following tests and treatments for allergies, as they are either unproven or disproven.[4]

  • Applied kinesiology (muscle testing)

  • Basophil histamine release/activation

  • Cytotoxicity assays

  • Electrodermal test

  • Endoscopic allergen provocation

  • Facial thermography

  • Gastric juice analysis

  • Hair analysis

  • Lymphocyte stimulation

  • Mediator release assay (MRT-LEAP diet)

  • Provocation neutralization

  • Pulse testing

Another form of misdiagnosis can come from confusing flu and cold symptoms for allergies caused by airborne particles (pollen, dust, pet dander). While these symptoms share many similarities, the chart below can help you tell the differences.

Difference between cold, flu, and allergy symptoms



Usual, high (100–102 °F), sometimes higher. Lasts 3–4 days.






General Aches, Pains


Usual; often severe


Fatigue, Weakness


Usual, can last up to 3 weeks


Extreme Exhaustion


Usual, at the beginning of the illness


Stuffy, Runny Nose








Sore Throat






Common, can become severe


Chest Discomfort

Mild to moderate


Rare, except for people with allergic asthma

Adapted from NIH News in Health. Cold, Flu, or Allergy? Know the Difference for Best Treatment.


An allergy treatment plan will vary based on allergy type and severity, but commonly includes medicines (antihistamines, bronchodilators, corticosteroids, allergy shots, nasal sprays, creams, and eye drops), avoiding the allergen, and lifestyle changes.

People who are at high risk of anaphylactic shock should take additional precautions, such as carrying epinephrine at all times. Consider discussing a specific treatment plan with your physician.

The table below displays an analysis of human studies and indicates which supplements may or may not affect allergies. While there is no cure-all supplement, some may aid in allergy control or symptom relief.

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Human Effect Matrix

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The Human Effect Matrix looks at human studies to tell you what supplements affect Allergies.

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Grade Level of Evidence
Robust research conducted with repeated double-blind clinical trials
Multiple studies where at least two are double-blind and placebo controlled
Single double-blind study or multiple cohort studies
Uncontrolled or observational studies only
Level of Evidence
? The amount of high quality evidence. The more evidence, the more we can trust the results.
Supplement Magnitude of effect
? The direction and size of the supplement's impact on each outcome. Some supplements can have an increasing effect, others have a decreasing effect, and others have no effect.
Consistency of research results
? Scientific research does not always agree. HIGH or VERY HIGH means that most of the scientific research agrees.
grade-c Strong Very High See 2 studies
Two studies found that spirulina is strongly effective in controlling allergies, with the symptoms of nasal discharge, sneezing, nasal congestion, and itching being reduced, and smell being improved. According to self-reports in one study, more than twice as many subjects in the spirulina group reported more than a 2-fold increase in satisfaction with treatment. In another study, it was comparable to or even more potent than the comparator pharmaceutical drug. More research is needed.
grade-c Strong - See study
At least in regards to allergic rhinitus, oral ingestion of tinospora cordifolia appears to abolish symptoms in 61-83% of persons (depending on symptom) extending to nasal blockage, mucus, pruritis, and sneezing.
grade-c Notable Very High See all 4 studies
Supplementation of the seed appears to beneficially influence most symptoms associated with allergies and most causes of the allergies (rhinitus, eczema, asthma, etc.), with the magnitude being somewhat notable among supplements.

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Frequently Asked Questions and Articles on Allergies

Which supplements can help against colds and the flu?
Vitamin C, vitamin D, zinc, and other supplements may provide an edge against colds and the flu, but they should only serve to complement your main defensive arsenal: good hygiene, proper hydration, healthy diet, restful sleep, stress control, and exercise.
Do probiotics improve quality of life in seasonal allergies?
Bacteria in the gut can influence the immune system, and the immune system plays a large role in seasonal allergies. So can probiotics influence allergic symptoms?
Click here to see all 34 references.