Types of Allergic Reactions: Rashes to Anaphylaxis

By Spader, Catherine, RN

Allergic reactions come in many forms, from a mild itch to a life-threatening reaction called anaphylaxis. How can the same substance cause a rash in one person and swelling of the airways in another? Read on to learn more about the different types of allergic reactions.

What Causes Allergic Reactions?

All allergic reactions occur when your immune system mistakes a normally harmless substance as potentially dangerous to your body and makes antibodies to fight the “threat.” This leads to the release of histamine, a chemical that produces swelling and inflammation of your tissues. An allergic reaction can affect any part of your body including your:

  • Skin

  • Eyes

  • Digestive tract

  • Respiratory tract

  • Brain and nervous system

  • Heart and circulatory system

There are varying levels of allergic reactions within a person and from one person to another. You inherit the tendency for allergies to various substances. If you have an allergy, it’s most likely that one of your parents has an allergy. Allergies are also quite common, with approximately one in six million Americans suffering from some form of allergy.

Allergic Rhinitis

Allergic rhinitis, frequently called hay fever, is the most common type of allergy. Allergic rhinitis affects your nose and may also affect your eyes. You may have a stuffy, runny nose; sneezing; itchy nose, mouth or throat; facial pressure; bluish gray circles under your eyes; and irritated eyes.

Allergic rhinitis can be caused by:

  • Animals with hair, fur or feathers

  • Medications

  • Pollen from trees, grasses and weeds

  • Dust mites or cock roaches

  • Mold

  • Foods, especially shellfish, milk, fish, nuts, peanuts, soy, wheat, and eggs

Allergic Conjunctivitis

Allergic conjunctivitis is a common type of allergic reaction that affects your eyes. You will have watery, itchy eyes as well as redness, puffy eyelids, and possibly discharge from your eye.

Common causes of allergic conjunctivitis include:

  • Pollen from trees, grasses and weeds

  • Animals with hair, fur or feathers

  • Perfumes and cosmetics

  • Skin medications

  • Smoke

  • Air pollution

Eczema

Eczema, also known as atopic dermatitis, is a common allergic skin condition. Eczema symptoms range from localized blisters to small red bumps that itch, flake, or scale. Symptoms worsen with abrupt temperature changes. The affected area may darken and your skin might grow thick from scratching it all the time.

Eczema is commonly caused by skin contact with:

  • Animals with fur or feathers

  • Chemicals, such as acids, solvents and dyes

  • Fragrances and perfumes

  • Latex and rubber

  • Nickel, a metal often used in jewelry

  • Plants, especially poison ivy, oak, and sumac

  • Soaps and detergents

Hives

Hives are a type of allergic reaction that affects your skin. Hives are raised red areas or welts that are often itchy. Hives can be small and few in numbers, but they can grow and spread causing large areas of raised skin.

The many substances that can cause hives include:

  • Cats and other animals with fur or feathers

  • Insect bites

  • Medications

  • Plant pollen

  • Foods, most commonly shellfish, milk, fish, nuts, peanuts, soy, wheat, and eggs

Allergic Asthma

Allergy-induced asthma is narrowing of the airways in your lungs. Tightening of your airways leads to coughing, shortness of breath, and wheezing, which is a whistling sound that you hear when you are breathing. You may also feel pressure or tightness in your upper chest.

Substances that commonly trigger allergic asthma include:

  • Cockroaches

  • Rodent droppings

  • Animals with fur or feathers

  • Foods, especially nuts, fish, and shellfish

  • Pollen

  • Dust mites

  • Mold

Anaphylactic Reactions

An anaphylactic reaction (anaphylaxis) is a life-threatening type of allergic reaction that affects your whole body. It is rare but most commonly caused by food, medication, insect stings, and latex. If not treated immediately, it can lead to shock, coma and death within about 15 minutes.

You may have:

  • Feeling of warmth, flushing and skin redness

  • Tingling, tightness or swelling of your eyes, face, throat, tongue or lips. This can lead to difficulty swallowing, your throat closing up, and an inability to breathe.

  • Wheezing and shortness of breath due to narrowing of the airways or fluid in the lungs (pulmonary edema)

  • Palpitations or chest pain due to an abnormal heart rhythm (arrhythmia)

  • Dizziness and passing out

  • Confusion and slurred speech

  • Very pale or bluish gray skin

  • Weakness

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Cockroaches can cause allergic reactions.

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