Understanding allergies and intolerances is essential for managing your health and well-being. These conditions occur when your immune system or digestive system reacts abnormally to certain substances. Read on to learn about common types, symptoms, and examples of allergies and intolerances.

What Are Allergies and Intolerances?

Allergies are exaggerated immune responses to typically harmless substances, such as pollen, pet dander, or certain foods. When you’re allergic, your body produces antibodies (IgE) that trigger symptoms like sneezing, itching, or even life-threatening reactions like anaphylaxis.

Intolerances, on the other hand, are non-immunological reactions. They often involve difficulties in digesting specific foods, leading to symptoms such as bloating, stomach pain, and diarrhea. For example, lactose intolerance occurs when your body lacks the enzyme needed to digest lactose, the sugar found in milk.

Common Allergy Examples

Food Allergies:

Examples: Peanut allergy, shellfish allergy, egg allergy.

Symptoms: Hives, swelling, difficulty breathing, and, in severe cases, anaphylaxis.

Environmental Allergies:

Examples: Pollen allergy (hay fever), mold allergy, pet allergy.

Symptoms: Sneezing, itchy and watery eyes, runny nose, and skin rashes.

Drug Allergies:

Examples: Allergic reactions to penicillin or other medications.

Symptoms: Rash, itching, swelling, and in rare cases, severe anaphylaxis.

Common Intolerance Examples

Lactose Intolerance:

Example: Inability to digest lactose in dairy products.

Symptoms: Bloating, gas, diarrhea, and stomach cramps after consuming dairy.

Gluten Intolerance (Non-Celiac Gluten Sensitivity):

Example: Reaction to gluten found in wheat, barley, and rye.

Symptoms: Bloating, abdominal pain, and fatigue after eating gluten-containing foods.

Histamine Intolerance:

Example: Difficulty breaking down histamine in foods like aged cheese, red wine, and processed meats.

Symptoms: Headaches, hives, and digestive issues.

Why Knowing Your Allergies and Intolerances Matters

Improved Health and Quality of Life:

Recognizing triggers helps you avoid harmful substances, reducing symptoms and preventing complications.

Personalized Diet and Lifestyle:

Identifying food intolerances can lead to tailored dietary plans that improve digestion and overall energy levels.

Enhanced Safety:

Awareness of severe allergies, such as peanut or insect sting allergies, is crucial. It allows you to carry emergency medication like an epinephrine auto-injector and avoid potentially life-threatening reactions.

Effective Treatment Planning:

With proper testing—such as skin prick tests for allergies or elimination diets for intolerances—you can work with healthcare professionals to develop strategies that manage your symptoms and improve your well-being.

Allergy testing is vital for diagnosing and managing allergic reactions. By measuring IgE antibody levels, these tests identify the substances causing your symptoms, helping doctors develop personalized treatment plans. Comprehensive allergy panels—including both food and environmental allergens—offer critical insights into your immune system’s behavior. At-home allergy tests make it easier than ever to determine your allergy status. If you suspect you have an allergy, consult your healthcare provider to choose the most appropriate test and begin managing your condition effectively.

What is Allergy?

Allergies are exaggerated immune reactions—such as sneezing, difficulty breathing, itching, or skin rashes—to substances or situations that don’t affect most people.

Symptoms

A person with allergies may experience:

• Itchy, watery eyes
• Sneezing
• Itchy, runny nose
• Feeling tired or ill
• Swollen lips, tongue, eyes, or face
• Vomiting or diarrhea

Types & Conditions

Drug Allergy

An abnormal immune reaction to a medication (distinct from common side effects or drug toxicity).

Food Allergy

An immune response that occurs shortly after eating certain foods, causing symptoms like digestive problems, hives, or swollen airways. In severe cases, it can lead to life-threatening anaphylaxis.

Insect Allergy

An abnormal reaction to insect bites, stings, or debris. Venom or bite fluids can trigger these reactions.

Latex Allergy

A reaction to proteins in natural rubber latex, which can cause itchy skin, hives, or anaphylaxis with symptoms like throat swelling and severe breathing difficulty.

Mold Allergy

An overreaction to inhaled mold spores that can cause coughing, itchy eyes, and, in some cases, trigger asthma symptoms.

Pet Allergy

A reaction to proteins found in an animal’s skin cells, saliva, or urine. Often triggered by pet dander, with cats and dogs being the most common culprits.

Pollen Allergy

An adverse reaction to pollen from trees, flowers, grasses, and weeds. The immune system mistakenly attacks pollen, producing chemicals that lead to allergy symptoms.

Primary Biomarkers for Allergies

Immunoglobulin E (IgE):

IgE is the primary antibody involved in allergic reactions. Elevated total IgE levels or allergen-specific IgE (measured via blood tests like ImmunoCAP or skin prick tests) indicate sensitivity to particular allergens such as pollen, pet dander, or certain foods.

Eosinophil Count:

Eosinophils are a type of white blood cell that increases during allergic inflammation. An elevated eosinophil count can be a strong indicator of conditions like asthma, allergic rhinitis, or atopic dermatitis.

Inflammatory Cytokines (e.g., IL-4, IL-5, IL-13):

These cytokines play crucial roles in the allergic response by promoting IgE production and eosinophil activation. Increased levels of these cytokines in blood or tissue samples can further confirm an allergic condition.

Serum Tryptase:

Tryptase is released by mast cells during allergic reactions, especially in severe cases such as anaphylaxis. Elevated baseline tryptase levels may help identify individuals with mast cell activation disorders.

Key Biomarkers for Intolerances

Immunoglobulin G (IgG):

While its role in food intolerance is debated, some tests measure specific IgG antibodies to common food proteins. Elevated IgG levels may indicate a delayed hypersensitivity reaction or food intolerance, helping guide dietary modifications.

Inflammatory Markers (CRP, IL-6):

Chronic low-grade inflammation can be associated with food intolerances. Elevated C-Reactive Protein (CRP) and IL-6 levels may signal an inflammatory response to certain foods, particularly in individuals with conditions like non-celiac gluten sensitivity.

Gut Permeability Indicators:

Biomarkers such as zonulin are emerging indicators of gut permeability (“leaky gut”), which can be associated with food intolerances and inflammatory responses. Elevated levels may suggest that larger food molecules are entering the bloodstream, triggering adverse reactions.

How Is Allergy Diagnosed?

Allergy testing helps determine which substances trigger your symptoms. Common methods include:

Skin Test: Small amounts of potential allergens are pricked into the skin (usually on the forearm or back). A raised bump (similar to a mosquito bite) within 15–20 minutes indicates an allergy.

Blood Test: Tests such as the Radioallergosorbent Test (RAST) or ImmunoCAP measure the levels of IgE antibodies in your blood to identify specific allergies.

Additional Testing Methods:

Intradermal Skin Test: Injects allergens just under the skin for more precise results, especially for substances like venom or penicillin.

Elimination Diet: Involves removing suspected foods from your diet and then gradually reintroducing them under medical supervision to observe any adverse reactions.

Who Should Run an Allergy Test?

Allergy testing should be conducted by healthcare providers—preferably allergists or immunologists—who can interpret your symptoms, choose the right tests, and safely administer them. It is recommended for:

Individuals with persistent symptoms like sneezing, itchiness, watery eyes, or hives.

Those with severe reactions such as swelling, breathing difficulties, or a history of anaphylaxis.

Children with asthma, eczema, or a family history of allergies, as early diagnosis can improve management.

Adults experiencing changes in their allergic responses.

What Foods Are Tested in Allergy Testing?

Common foods include:

Cow’s milk

Eggs

Shellfish

Tree nuts (e.g., walnuts, almonds, Brazil nuts, cashews)

Peanuts

Wheat

Soy

Fish

Are Food Allergy Tests Reliable?

Food allergy tests, including skin prick tests and blood tests (e.g., ImmunoCAP or RAST), measure IgE antibodies to determine sensitivity. However, they can sometimes produce false positives, so test results should be considered alongside your medical history and symptoms. An oral food challenge, performed under strict medical supervision, remains the most reliable method to confirm a food allergy.