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Allergies and your immune system: What is the link?

 Allergies and your immune system: What is the link?

If you know anything about the human immune system it’s probably that if yours is weaker than it should be, you could be more susceptible to infections. But the immune system can also be overactive and react strongly to something that’s completely harmless – in other words, an allergic reaction. So if you have one or more allergies, it’s not a sign your immune system is weak. In fact, you could argue it’s quite the opposite.

Your immune system is a complex network of cells, proteins and organs that work together to protect you against infection by viruses, bacteria, parasites, fungi and other harmful micro-organisms (pathogens). Normally it’s a highly efficient system – immune cells recognise a pathogen, and that triggers a response from the rest of the immune system to hunt and destroy the pathogen.

If you have an allergy, however, your immune system mistakenly recognises something non-infectious as a pathogen – pollen, in the case of hay fever for instance. It overreacts, believing you’re under threat, and the result is an immune system attack that was never necessary in the first place.

Besides pollen, some of the common substances that confuse your immune system in this way include dust mites, some medicines, moulds, pet dander (tiny particles of skin shed by animals that have fur or feathers), insect venom and certain foods, all of which are classed as allergens.

How an allergy starts

Around a third of people have one or more allergies at some point in their lives (i). Certain types of allergies run in families, which suggests that some of us are genetically predisposed to developing them. But how do they start in the first place?

First you must be exposed to an allergen before you can develop an allergy to it (you can’t have an allergy to something you have never encountered). This is called sensitisation. It can happen the first time you come into contact with an allergen, or it can happen after you’ve encountered the allergen time after time for years with no ill effect.

When you become sensitised an allergen enters your body – your nose, eyes, skin, lungs or stomach – and, for some unknown reason, some of your immune cells detect it and ‘present’ it to other immune cells as a foreign invader or pathogen. Some of these immune cells called B-lymphocytes (white blood cells) then produce a type of antibody called immunoglobin E (IgE) in a form that’s specific to that particular allergen. The IgE antibodies are released into the bloodstream, where they bind to certain immune cells, including ones that live in tissues in the body called mast cells.

You won’t experience an allergic reaction at this stage, but if you come into contact with that allergen again it can bind to IgE on mast cells, which can then trigger an immediate immune response (though this doesn’t happen in everyone – in fact, according to the British Society for Immunology, some people can go their whole life carrying allergen-specific IgE-bound mast cells without ever experiencing an allergic reaction (ii) ).

Mast cells are made up of granules that break down or activate when this binding process happens, which results in the release a series of chemicals. The best-known chemical released by mast cells is histamine. When this gets out of mast cells it can cause a range of allergy symptoms, including itching, sneezing and wheezing. Other chemicals released by mast cells include leukotrienes, which have a similar effect on your body as histamine, and cytokines, some of which tell your immune system to make more IgE.

Tissues that have been affected by mast cell chemicals can also become sore and swollen, causing inflammation and even more longer-lasting allergy symptoms.

What are typical allergy symptoms?

If you have one or more allergies, you may have symptoms that affect your airways, sinuses, nasal passages, skin or your gastrointestinal system.

Allergic rhinitis

There are two types of allergic rhinitis – the seasonal type, which is more commonly called hay fever, and perennial allergic rhinitis, which can affect you year round. If you have hay fever, your immune system is reacting to pollen released by plants (trees, grasses, weeds etc), which is why most people affected get symptoms during the spring and summer months. Perennial allergic rhinitis can be caused by a number of allergens, including dust mites, pet dander and mould.

Symptoms of both types of rhinitis include cold-like symptoms such as sneezing, a blocked or stuffy nose and an itchy nose. These symptoms are triggered by the release of immune system chemicals in the inside layer of your nose (mucous membrane), making your nasal passages produce mucous and become swollen.

Find out more in our article What is hay fever?


If you have asthma, your airways become swollen and more narrow, which can make breathing difficult. This inflammation is often caused by exposure to a trigger such as cold air, cigarette smoke or pollution. However allergies can also trigger asthma symptoms. Allergens that typically trigger asthma symptoms include those that you inhale such as dust mites, animal fur and pollen. According to the American Academy of Allergy, Asthma & Immunology, up to 78 per cent of people with asthma also have allergic rhinitis (iii).

The symptoms of asthma include shortness of breath, wheezing, chest tightness and coughing. You can read more about it in our guide to asthma symptoms.


Also called dermatitis, eczema is often the result of an allergen coming into contact with your skin (typical allergens include detergents, perfumes and soaps). The most common form of eczema is atopic eczema: atopic means sensitivity to allergens, which may explain why many people with atopic eczema also have other allergies such as asthma and hay fever (iv).

Symptoms of eczema are itchy, dry, cracked and sore skin. Some people may find only small areas of their skin are affected, while others with more severe eczema may have inflamed skin all over. There’s more information about how you can help yourself in our article Eczema: treatment & support.


Urticaria is more commonly known as hives. It’s another allergy that affects your skin, but this time it’s usually triggered by something you eat or when you take a particular type of medicines (other urticaria triggers include dust, pollen and insect bites and stings).

The symptoms include itchy, red, raised patches on your skin, or red spots. The rash can also feel as if it’s stinging or burning. Thankfully urticaria dies down fairly quickly, often within just a few hours – though you can experience it for longer.

Read more about it in our article What is urticaria?

Allergic conjunctivitis

This type of allergy can be triggered when your eyes come into contact with allergens such as pollen, dust mites, pet dander or chemical ingredients in cosmetics, make-up and eye drops. Some of these things may affect you all year round, such as dust mites. This means you could experience sore, watery, itchy, puffy eyes that feel hot and gritty on a regular basis. Some people can also develop conjunctivitis through wearing contact lenses.

There’s more information in our guide to conjunctivitis.

Severe allergy: anaphylaxis

Some types of allergies trigger a severe reaction called anaphylaxis. The allergens that typically trigger anaphylaxis include insect bites or stings, foods and medicines. The way the immune system reacts is the same for anaphylaxis as other allergies – that is, the reaction starts when IgE binds to the allergen and activates the release of chemicals from mast cells.

With anaphylaxis, symptoms start suddenly, get worse very quickly and can be very severe. These include breathing difficulties, lightheadedness or fainting, rapid heartbeat, clammy skin, anxiety and losing consciousness. Sometimes you can also experience other allergy symptoms with anaphylaxis, including urticaria and swelling.

Since these symptoms can be potentially life threatening, anaphylaxis is considered a medical emergency. Find out more by reading our guide to anaphylaxis.

Natural support for allergies

If you have an overactive immune system that is causing an allergy or allergies, there are treatments that may help control your symptoms including antihistamine medicines and drugs that help manage inflammation. In the meantime there are several things you could do to help yourself live with your allergy symptoms:

Eat healthily

Try to make sure you have a healthy, nutritious, balanced diet that includes lots of fruit and vegetables.

Get plenty of sleep

Avoiding having too many late nights is also a good idea, as sleep helps support your immune system to function normally. How much sleep is the right amount depends on the individual, but in general you should be aiming for something between six and nine hours a night.

Tackle stress

Managing your stress levels can help with allergies, since experts believe stress could make your symptoms worse as well as increase the frequency of allergy flare-ups (v). Try practising deep breathing or meditation, taking part in relaxing activities you enjoy – or just make time on a regular basis to take things easy.

Avoid allergens

It may go without saying, but wherever possible try to avoid or limit your exposure to any allergens that trigger your allergy symptoms. This can be tricky with some allergens, such as airborne ones for instance. If you have hay fever, spending time indoors with your windows and doors closed whenever the pollen count is high may limit your exposure. If your allergen is an indoor one - dust mites, for instance – using a HEPA filter (either a freestanding filter or one that comes in a vacuum cleaner) may be helpful. Using anti-allergy bedding may also help with dust mite allergy.

Try nutritional supplements

There are a few natural supplements you could try, either on their own or alongside conventional allergy medicines. The main ones include:

  • High-strength multivitamin and mineral – this can help support your overall health and immune system.

  • High-strength fish oils – these are widely thought to have an anti-inflammatory action. One study even suggests a diet rich in one of the two main omega-3 fatty acids found in oily fish as well as vitamin C may reduce your risk of having hay fever (vi).

The omega-3 fatty acids found in fish such as salmon, trout, herring and mackerel are also now available in vegetarian and vegan supplements, where they are sourced from plant organisms called microalgae instead of fish.

  • Vitamin C – thought to be a natural antihistamine, vitamin C is found in many fruits and vegetables as well as supplements. One study has found that high doses of vitamin C may reduce allergy symptoms, and that a deficiency in vitamin C could lead to allergies (vii). An earlier study also suggests vitamin C may act as an antihistamine if you take 2g of it a day (viii).

  • Vitamin D - supplements containing vitamin D have been shown in studies to improve asthma control, with researchers suggesting this may happen because of the role vitamin D plays in modulating the immune system (ix). Vitamin D3 is the natural form of the vitamin that your body makes when your skin is exposed to sunlight, which is why many natural practitioners recommend it. Supplements containing vitamin D3 are widely available – you can also get them in veggie-friendly drops as well as vegan products sourced from lichen rather than the fat from lamb’s wool.

  • Quercetin – lab tests show that this substance, a member of the bioflavonoid family, may help to prevent the release of histamine from immune cells (x). Quercetin is available as a supplement, but you can also get it in foods such as onions, black tea, blackberries, kale, blackcurrants, yellow and green peppers and broccoli.

There’s lots more to discover about immune health in our Immunity pages. For information on a wide range of health issues, visit our pharmacy health library


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Disclaimer: The information presented by Nature's Best is for informational purposes only. It is based on scientific studies (human, animal, or in vitro), clinical experience, or traditional usage as cited in each article. The results reported may not necessarily occur in all individuals. Self-treatment is not recommended for life-threatening conditions that require medical treatment under a doctor's care. For many of the conditions discussed, treatment with prescription or over the counter medication is also available. Consult your doctor, practitioner, and/or pharmacist for any health problem and before using any supplements or before making any changes in prescribed medications.

Our Author - Christine Morgan


Christine Morgan has been a freelance health and wellbeing journalist for almost 20 years, having written for numerous publications including the Daily Mirror, S Magazine, Top Sante, Healthy, Woman & Home, Zest, Allergy, Healthy Times and Pregnancy & Birth; she has also edited several titles such as Women’ Health, Shine’s Real Health & Beauty and All About Health.

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