Allergies: Causes, Symptoms, Triggers, and Management Tips

What Are Allergies?

Allergies are your immune system’s response to substances that are not a threat, but it perceives them as such. These substances or foreign objects are what you may know as “allergens.”

Any interaction that you may have with these allergens, be it via skin contact, inhalation, or through the food you eat, can trigger an allergic reaction.

Depending on the allergen and how your body responds to it, this reaction can cause symptoms ranging from mild skin irritation and sneezing to more severe reactions that require immediate medical attention.

What is Anaphylaxis?

Anaphylaxis is a severe allergic reaction that can develop rapidly and affect breathing, blood pressure, and multiple parts of the body. It can be life-threatening and requires immediate medical attention, especially if it causes breathing difficulties or throat swelling.

What Causes Allergies?

An allergic reaction generally occurs after the immune system has already become sensitised to an allergen. This means that when you first get exposed to an allergen, your body produces antibodies called immunoglobulin E (IgE) to work against it.

When you encounter the same allergen again, these antibodies trigger the immune response that produces allergy symptoms.

Some people are more likely to develop allergies than others. Your risk of developing an allergy may be higher if your biological parent has allergies and if you have an atopic condition, such as asthma or eczema.

Is There a Connection Between Gut Health and Allergies?

Research suggests that the gut microbiome, the community of microorganisms living in your digestive tract, may influence how your immune system responds to allergens. Changes in the gut microbiome have also been associated with allergic conditions such as food allergies, respiratory allergies, and atopic dermatitis.

However, the relationship is complex, and researchers are still studying whether these changes directly contribute to allergies.

What Are the Types of Allergies?

Based on the substance that triggers the reaction and the part of the body it affects, allergies generally get grouped into seven types: food, medicines, insect venom, latex, respiratory, pets, and skin allergies.

The symptoms can also vary considerably between these types. For example, a food allergy may primarily affect the digestive system, while a respiratory allergy may cause nasal or breathing symptoms.

Different allergies can affect different parts of the body depending on the allergen and how you are exposed to it.

Food Allergy

Eating a food that your immune system reacts to can cause symptoms such as tingling in the mouth, swelling of the lips, tongue, or face, widespread itching, and difficulty breathing. Severe reactions can progress to anaphylaxis.

Drug Allergy

Certain medicines can trigger an immune reaction that causes symptoms such as a skin rash, itching, facial or body swelling, coughing, chest tightness, or breathing difficulties. Severe drug allergies can also cause anaphylaxis.

Insect Allergy

Reactions to insect stings can cause pain, redness, and swelling around the affected area. Some people may also develop widespread itching, hives, wheezing, or difficulty breathing.

Bees, wasps, hornets, and fire ants are among the insects that can cause severe allergic reactions.

Latex Allergy

When the immune system reacts to proteins found in natural rubber latex, it can trigger an allergic reaction. Exposure can happen through products such as latex gloves and balloons. The symptoms of latex allergy can range from skin symptoms to severe breathing problems and anaphylaxis.

Respiratory Allergy

Respiratory allergies include conditions such as allergic rhinitis and allergy-related asthma. They are commonly triggered by allergens such as pollen and dust mites.

The symptoms you may experience due to respiratory allergies include a runny or blocked nose, coughing, wheezing, chest tightness, and shortness of breath.

Pet Allergy

Pet allergies develop when the immune system reacts to proteins found in substances released by animals. These allergens can be present in the animals’ fur, saliva, skin flakes, and urine. Exposure to them may cause sneezing, a blocked nose, itchy or watery eyes, skin irritation, or hives.

Skin Allergy

Skin allergies, including contact dermatitis and hives, can develop after contact with substances such as certain cosmetics, soaps, detergents, or plants. Depending on the trigger, the skin may become itchy, red, swollen, flaky, or blistered.

What Are the Symptoms of Allergies?

Allergy symptoms depend on the allergen and the part of the body involved. They can affect the skin, airways, nose, eyes, and digestive system, and their severity can range from mild irritation to a serious allergic reaction.

Generally, allergens affect the skin, eyes, and the respiratory and digestive systems, and lead to the following symptoms:

• Skin rash or hives
• Itchy skin
• Sneezing
• A stuffy or runny nose
• Coughing
• Wheezing
• Itchy or watery eyes
• Swelling of the face, lips, tongue, or throat
• Difficulty breathing or swallowing
• Vomiting or diarrhoea

However, different types of allergies can also produce more specific patterns of symptoms.

What Are the Symptoms of Food Allergies?

A food allergy can affect several systems at once. Skin symptoms such as hives and swelling are the most common, often alongside symptoms in the mouth, throat, or the gut.

So, when you eat something you are allergic to, an immediate immune reaction gets triggered throughout your body, leading to:

• Tingling or an unusual sensation in the mouth
• Swelling of the lips, tongue, face, or throat
• Stomach cramps, vomiting, or diarrhoea
• Raised, itchy welts called hives
• A blocked or runny nose and itchy, watery eyes
• Anaphylaxis in severe cases

What Are the Symptoms of Medicine Allergies?

An allergic reaction to a medicine can show up in different ways, ranging from mild skin symptoms to more serious reactions.

When your body misinterprets a medication as a threat, it can trigger widespread skin and breathing reactions, such as:

• Hives or an itchy rash
• Skin irritation
• Swelling of the face
• Wheezing
• Shortness of breath
• Vomiting or diarrhoea
• Dizziness
• Anaphylaxis in severe cases

What is Hay Fever?

Hay fever, also called allergic rhinitis, is an allergic reaction to airborne allergens, such as dust particles and pollens.

When airborne allergens inflame the nasal passages and airways, they typically trigger several noticeable physical responses:

• Persistent sneezing
• Itching in the nose, eyes, skin, or roof of the mouth
• A runny or blocked nose
• Fatigue
• Red, watery, or swollen eyes

Some of these symptoms may not necessarily be caused by an allergy and could also occur due to other conditions. If you experience these symptoms and are unsure of the cause, consult your doctor for appropriate evaluation.

If your throat starts to close or you experience chest tightness or difficulty breathing, seek prompt medical attention, as these may be signs of a serious allergic reaction.

How Is Allergy Diagnosed?

Doctors diagnose allergies by looking at your symptoms, possible triggers, medical history, and the pattern in which your reactions occur. A diagnosis does not usually depend on a test alone.

Initially, your doctor may ask you about the exact symptoms you experience and when they occur. To better understand your condition, they may also ask you to maintain a written record of your symptoms and note down any possible triggers.

To confirm their diagnosis or to rule out other possible causes, your doctor may rely on two primary diagnostic evaluations:

Skin Test

A small amount of a suspected allergen is introduced into the skin, usually through a tiny prick. If you are sensitised to that allergen, the area may develop a raised, itchy bump.

In some situations, a doctor may recommend an intradermal test, in which a small amount of allergen is injected into the skin.

Blood Test

A blood test can measure allergen-specific IgE antibodies. Your blood sample is analysed in a laboratory to check for sensitisation to particular allergens.

Neither test should be interpreted on its own. A positive result indicates sensitisation, but your doctor needs to consider your symptoms and medical history to determine whether the allergen is actually responsible for your reactions.

How Can You Manage Allergies?

Managing allergies starts with identifying the substances that trigger your symptoms and reducing your exposure to them where possible. Depending on the allergy, your doctor may also recommend medicines or other treatments to control symptoms and reduce the risk of severe reactions.

To cut down on allergic flare-ups and lower the amount of triggers in your daily environment, you can take these proactive steps:

Identify and Avoid Triggers

Keep track of when your symptoms occur and what you were exposed to around that time. Once a trigger is identified, reducing exposure to it can help prevent future reactions.

Depending on the allergy, this may mean limiting exposure to pollen, dust, mould, smoke, strong fragrances, certain foods, or specific medicines.

Keep Your Indoor Spaces Clean

Regularly clean surfaces and wash bedding to reduce indoor allergens. Good ventilation can also improve airflow, while an appropriate air purifier may help reduce certain airborne particles.

Monitor Symptom Patterns

Keeping a record of your symptoms can help reveal patterns that may otherwise be easy to miss.

Note when symptoms appear, what you were doing, what you ate, and any possible exposure to an allergen. This information can also help your doctor refine your treatment plan.

When Should You Consult a Doctor?

Consider seeing a doctor if allergy symptoms keep returning or interfere with your daily activities. You should also speak to your doctor if symptoms begin after starting a new medicine, particularly if the reaction involves swelling, a rash, or breathing difficulties.

Persistent nasal symptoms, including frequent nasal blockage, recurring sinus infections, persistent coughing, and breathing discomfort, should not simply be ignored either.

Medical advice can also help determine whether recurring symptoms are actually caused by an allergy or another condition.

Can Allergies Be Treated?

There is no single treatment that works for every type of allergy. However, there are a few treatment approaches that help manage the symptoms and reduce inflammation.

Based on the allergens that affect you, the symptoms you experience, and their severity, your doctor may recommend:

• Antihistamines: These medicines can help manage symptoms such as itching, sneezing, and a runny nose.
• Steroid nasal sprays: These can reduce inflammation inside the nose and are commonly used for allergic rhinitis.
• Leukotriene modifiers: Medicines such as montelukast may be prescribed in certain cases, particularly when allergic symptoms occur alongside asthma.
• Biologic medicines: Some people with specific allergic conditions may be prescribed medicines such as omalizumab under specialist supervision.
• Allergen immunotherapy: This treatment gradually exposes the immune system to controlled amounts of a specific allergen. Depending on the allergy, it may involve allergy shots or forms of sublingual or oral immunotherapy.

The appropriate treatment depends on your diagnosis, so do not start prescription allergy medicines or immunotherapy without medical guidance.

Treatment for Anaphylaxis

Anaphylaxis requires immediate treatment because the reaction can worsen rapidly. Adrenaline (epinephrine) is the first-line treatment and is typically given using an auto-injector, such as an EpiPen, when available. After using an adrenaline auto-injector, seek emergency medical care immediately, even if the symptoms begin to improve.

Mool Health’s Perspective on Allergies

Allergies can look very different for different individuals. The same allergen that causes mild symptoms in one person may cause a more severe reaction in another.

At Mool Health, we believe that looking at your health as a whole can help you better understand factors that may influence how your body responds to allergens. This includes considering your gut health, given its potential role in immune regulation.

The Mool Health Gut Test can help you learn more about your gut health and identify areas that may need attention.

References

Pascal, M., Perez-Gordo, M., Caballero, T., Escribese, M. M., Lopez Longo, M. N., Luengo, O., Manso, L., Matheu, V., Seoane, E., Zamorano, M., Labrador, M., & Mayorga, C. (2018). Microbiome and Allergic Diseases. Frontiers in Immunology, 9, 1584. DOI: 10.3389/fimmu.2018.01584. https://pmc.ncbi.nlm.nih.gov/articles/PMC6056614/

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Cleveland Clinic. (2025). Allergies: Types, Symptoms, Treatment & Management. Cleveland Clinic. https://my.clevelandclinic.org/health/diseases/8610-allergies

Cleveland Clinic. (2024). Pet Allergies: What You Need to Know. Cleveland Clinic. https://my.clevelandclinic.org/health/diseases/17702-pet-allergies

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Asthma and Allergy Foundation of America. (n.d.). Types of Allergies. AAFA. https://aafa.org/allergies/types-of-allergies/

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