Allergic Reactions

We all overreact to certain situations in life—some of us more than others (slowly raises hand). But when your immune system overreacts to a harmless substance, also known as an allergen, your body responds by triggering an allergic reaction—the runny nose, watery eyes, itchy skin, sneezing, and wheezing you experience when you’re just trying to pet your dog or enjoy a beautiful spring day.

Allergies are one of the most common chronic diseases and impact more than 50 million Americans each year, according to the American College of Allergy, Asthma, & Immunology (ACAAI). More specifically, they are the sixth leading cause of chronic illness in the United States.

“An allergic reaction is due to a sensitization of our body’s immune system to an outside allergen,” Omid Mehdizadeh, MD, an otolaryngologist and laryngologist at Providence Saint John’s Health Center in Santa Monica, California, tells SELF. In other words, an allergy occurs when the immune system sees a substance as harmful (even though it’s not) and overreacts to it.

Identifying potential allergens that cause you to sneeze like crazy or break out in hives can help you differentiate between mild reactions that are manageable at home and severe reactions that scream, “Get to the emergency room right away!” Here is everything you need to know about the types of allergic reactions, common symptoms, causes, and how to treat them.

Allergic reactions can range from mild to severe and can be life-threatening.

Amanda K Bailey

It’s no secret that your immune system works hard to protect the body from viruses, diseases, and infections. However, in some people, the immune system sees a non-threatening substance (an allergen) as harmful, which sets off a whole host of reactions. Your body responds by making antibodies called immunoglobulin E (IgE), which cause certain cells to release chemicals like histamine into the bloodstream to defend against the allergen. This sets off a cascade of symptoms that you know of as an allergic reaction.¹

Allergic reactions can range from mild to life-threatening and may cause symptoms in the nose, sinuses, throat, lungs, ears, skin, or lining of the stomach, according to the American Academy of Asthma & Immunology (AAAAI). While not an exhaustive list, Dr. Mehdizadeh says foods—like gluten, dairy, soy, shellfish, and nuts—pollen, metals, ragweed, dust mites, grasses, and dander, top the list of common allergens.

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If it seems like the list of allergic reactions is long, you’re not mistaken. Allergic reactions can affect your eyes, nose, skin, and lungs. Clinically, experts even distinguish between different classifications of reactions. “There are different types of allergies and allergic reactions, which are classified by the types of cells involved,” Edith Schussler, MD, a pediatric allergy and immunology specialist at Weill Cornell Medicine and New York–Presbyterian, tells SELF. Dr. Schussler says type 1 reactions are immediate, and the type most people think of when talking about being allergic to something like pollen, pets, or food.² “It’s also the type that is mediated by IgE antibodies and may cause anaphylaxis,” she explains. Type 2 through 4 allergic reactions involve different body processes and chemicals and are typically more delayed reactions than type 1. Because type 1 allergic reactions are what most people experience, that’s what we’re going to focus on here.

Type 1 allergies generally produce symptoms quickly—within a few seconds to minutes. They include food allergies such as peanuts, tree nuts, milk, soy, egg, fish, and shellfish, as well as environmental allergies related to pollen, pets, and other allergies that result in a runny nose, congestion, watery itchy eyes, and postnasal drip. Some but not all drug allergies are IgE mediated, meaning they fall in line with type 1 allergic reactions, says Dr. Schlusser.

Here are a few more details about how type 1 allergic reactions typically show up:

• Nasal: Hay fever or allergic rhinitis, which can be seasonal or happen yearlong, causes inflammation in the nasal lining and increases  sensitivity to inhalants. Common triggers are pollen, pet dander, mold, dust mites, smoke, strong odors, or changes in humidity and temperature.³
• Eyes: When an allergen irritates the conjunctiva (the white part of your eye) you may experience what’s called allergic conjunctivitis or ocular allergy.⁴ This produces symptoms like itching, swelling, and redness in the eyes. Nasal and eye symptoms often occur together. Causes include pollen, mold spores, dust mites, and pet dander, per the AAAAI.
• Skin: When your skin comes into contact with an allergen, you may experience atopic dermatitis or eczema, which causes your skin to itch, flake, peel, or get red. Hives, which are red itchy bumps on the skin, are another common allergic reaction symptom. These can be large or small and often occur in clumps. Causes for hives include physical contact with an allergen (including foods), heat, medications, or insect bites, according to the AAAAI.
• Lungs: Allergic asthma causes inflammation and swelling inside the airways of the lungs, making it difficult to breathe when you inhale an allergen. Allergic asthma is typically triggered by allergens like pollen, pet dander, dust mites, mold, tobacco smoke, or strong odors, per the Asthma and Allergy Foundation of America (AAFA).
• Food allergy: This is one of the few allergies that can cause anaphylaxis, which is a life-threatening condition (more on this in a bit). Common food allergies include cow’s milk, eggs, fish, peanuts, shellfish, soy, tree nuts, and wheat, according to the AAAI. Coming into contact with a food allergen can cause hives, nasal issues, vomiting, stomach cramps, diarrhea, throat tightness, wheezing, chest tightness, trouble breathing, and tingling in the hands, feet, and lips.⁵

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