Allergy- Definition, Types, Causes, and Symptoms

A medical disease in which the body’s immune system reacts improperly to a foreign substance is known as an allergy. An allergen is a substance that induces an allergic reaction. There are different Types and Symptoms of Allergies.

Different people are sensitive to one or more of these particles in our environment. Their immune system reacts in very different and overactive ways to these particles. In this article, we will learn about allergies, their types, and their symptoms. By the end of this article, you will understand allergic reactions and the reasons behind them.

What is Allergy?

An allergy is an exaggerated or overactive immune response to foreign substances such as pollen, dust, mites, certain medications, bee venom, pet dander, or maybe a food item. These foreign substances that cause allergies are called allergens. Allergy is typically not harmful to one’s body. People who are prone to allergies are called allergic or atopic. When an allergic person comes in contact with an allergen, the immune system responds by producing IgE antibodies. Dust allergy is the most common type of allergy in India.

Fig: Allergy

Types of Allergies

There are many types of allergies depending upon the type of allergens. Some of the allergies are seasonal, and others are year-round. Some of the allergies may be lifelong to a person.  Different types of allergies are discussed below:

1. Drug Allergy: It is also called medicine allergy. True drug allergy is very rare to diagnose in people. People with certain drug allergies have an oversensitive immune system. Their immune system considers the medicine as an invader and reacts to it. Common symptoms of drug allergy are hives, rashes, or fever.

2. Food Allergy: Food allergy occurs when one’s immune system reacts to certain food items, considering it a harmful invader. Even a small amount of allergy-causing food (allergen) can trigger symptoms like digestive problems, vomiting, nausea, hives, or swollen airways. In adults, most food allergies are due to peanuts, shellfish, and tree nuts. In children, food allergies are due to milk, eggs, wheat, soy, peanuts, tree nuts, and shellfish.

3. Insect Allergy: There are many insects or insects-like bugs that can cause insect allergies. Bees, hornets, wasps, yellow jackets, fire ants are the most common stinging insects that cause allergic reactions. Some non-stinging insects like cockroaches and dust mites also cause allergies. Insect allergy is the most common cause of asthma and year-round allergy.

4. Latex Allergy: Latex allergy is a type of allergy caused by natural rubber latex. Latex rubber makes many products like gloves, balloons, rubber balls, bandages, etc. Contact with these latex products may cause an allergic reaction. Some people might have breathing problems skin problems due to repeated contact with latex products.

5. Mold Allergy: Molds are tiny fungi with spores that float in the air like pollen. Molds can be found in damp indoor areas like the kitchen, bathroom, basement, or outside under the mushroom, leaves, or in the grass in humid weather. Inhaling the spores of these fungi causes allergic reactions in some people. Mold allergy is common in July to early fall.

6. Animal/Pet Allergy: Some people have allergies to animals or pets. Most commonly, pets with fur cause pet allergies in some people. Allergies with cats are more common than allergies with dogs. People with pet allergies may be more sensitive to a certain breed of pet, e.g. dogs and cats. The oversensitive immune system of such people reacts to harmless proteins such as a pet’s urine, saliva, or dander (dead skin cells).

7. Pollen Allergy: Pollen allergy is the most common type of seasonal allergy. Many people call pollen allergy hay fever. Some experts called this seasonal allergic rhinitis. In seasons like spring, summer, and fall, plants produce small pollen grains to fertilize other plants of the same species. The majority of these pollen grains that cause allergic reactions come from trees, weeds, and grasses. Symptoms of a pollen allergy may include runny nose, mucus production, sneezing, itchy and stuffy nose, itching eyes, etc.

Fig: Types of Allergy

Risk Factors of Allergies

1. Allergies can affect anyone of any age. Most children are more prone to allergies. First-time events of allergy can happen at any age.
2. It is unclear why one person develops a certain kind of allergy and others don’t.
3. If a person has a family history of a certain kind of allergy like asthma, dust allergy, pollen allergy, then he/she may have inherited the risk of having the same allergy.
4. Children born with cesarean section have a higher risk of allergy than children born vaginally.5. In the case of sensitive people, certain irritants in the environment, hormones, stress, smoke, perfume also cause allergic reactions.
6. Symptoms of allergy grow slowly.
7. Exposure to tobacco smoke, harmful gases, and air pollution increases allergies.
8. Boys are more prone to allergies as compared to girls.
9. Allergies are most common in westernized countries. It is less common in people with a farming lifestyle.

Causes of Allergies

1. If allergens that cause allergy are inhaled, swallowed, or if they come in contact with a person’s skin, it causes an allergic reaction in that person.
2. The oversensitive immune system of such people considers these harmless foreign substances as harmful and dangerous invaders. The immune system produces IgE antibodies to attack these harmless allergens as a response to this.
3. When that person comes in contact with that allergen once again, certain chemicals such as histamine, cytokines, and leukotrienes are released, which cause allergic symptoms.
4. Allergic reactions and symptoms differ with the type and amount of allergens one has come in contact with.
5. one person may be allergic to only one type of allergen and not the other.
6. The most common allergens are pollen, dust, mites, latex, food, medicines, animal dander, urine, insect bites, stings, etc.
7. Allergies might have a genetic component. This means parents can pass on their allergies to their children.
8. Allergies can increase the risk of other medical problems such as anaphylaxis, asthma, sinusitis, and infection of the ears or lungs.

Fig: Causes of Allergy

Symptoms of Allergies

Allergic reactions can have different symptoms and can affect different body parts. Some of the common symptoms of allergic reactions are:

1. Red, itchy, watery eyes
2. Stuffy nose, sneezing, runny nose, itching in the nose
3. Itching in the ear or on the roof of the mouth
4. Red, itchy, dry skin
5. Itchy rashes on the skin
6. Hives or itchy welts
7. Facial swelling
8. Nausea and vomiting
9. Redness and swelling of the skin
10. Flaking or peeling of skin
11. Symptoms of Asthma-like coughing,  shortness of breath, wheezing
12. Anaphylaxis, a severe life-threatening reaction

Fig: Symptoms of Allergy

Common Allergic Conditions

The most common allergic conditions include Hay fever, Asthma, Sinusitis, Hives, anaphylaxis, and Atopic Eczema (Dermatitis), which are given in detail below:

1. Hay fever: Hay fever is also called seasonal allergy or rhinitis. The farmers coined the term ‘Hay fever’ because they observed the same symptoms every year during harvest season. Hay fever is like having a cold. Due to hay fever, the tissue lining our nose becomes inflamed, causing a stuffy feeling. Hay fever symptoms may include sneezing, runny nose, scratchy throat, red and itchy eyes, etc.

2. Asthma: It is a disease affecting the airways that carry air in and out of the lungs in our body. Anyone can suffer from asthma. Most children by age 5 and adults in their 30s can get asthma. Asthma can be passed through parents to their children. Symptoms of asthma include coughing, wheezing, shortness of breath, chest tightness, or producing a lot of mucus.

3. Sinusitis: It is the inflammation of the mucous membranes in the sinuses. It is caused by infection, allergies, and irritation from toxic substances in the air. Sinusitis can be acute or chronic.

4. Hives: It is also called urticaria. They are raised red welts of various sizes on the skin’s surface. They are often itchy and associated with an allergic reaction and histamine release or abnormalities in parts of the immune system.

5. Atopic Eczema: It is also called dermatitis. It is a type of hereditary disease. Symptoms may include superficial inflammation, redness, oedema, oozing, crusting, scaling, and intense skin’s itching. Over scratching may lead to bleeding and infection.

6. Anaphylaxis: It is an acute type of allergic reaction. Symptoms of it include wheezing, difficulty breathing, and gastrointestinal symptoms—abdominal pain, vomiting, diarrhoea and cramps, low blood pressure, pulmonary edema, the occurrence of Hives and angioedema (hives on the lips, eyelids, throat, etc.).

Summary

The exaggerated and overactive reaction of the immune system to certain foreign substances is called allergy. The foreign substances which cause allergies are called allergens. A person who has an allergy is called allergic or atopic. In most cases, allergy is not harmful to the human body. When an allergic person comes in contact with an allergen, the immune system responds by producing IgE antibodies. Symptoms of an allergy include red, itchy, watery eyes, stuffy nose, sneezing, runny nose, itching in the nose, itching in the ear or on the roof of the mouth, red, itchy, dry skin, etc. Allergy is most common in children. It can be hereditary. Various types of allergies include dust allergy, food allergy, drug allergy, latex allergy, etc. Common allergic conditions include Hay fever, Asthma, Sinusitis, Hives, anaphylaxis, Atopic Eczema (Dermatitis), etc.

FAQs

Q.1. What is an allergy?
Ans: Allergy is an exaggerated and overactive reaction of our immune system to certain foreign substances (allergen).

Q.2. What causes an allergic reaction?
Ans: Various kinds of allergens like dust, mites, latex, pollens, foods, chemicals, drugs, etc. are responsible for allergic reactions in our body.

Q.3. Who develops allergies?
Ans: Allergies can affect anyone regardless of age or gender. It is observed that boys suffer more from the allergy than girls. Allergies are also inherited by parents to their children.

Q.4. What are different types of allergies?
Ans: Different types of allergies include drug allergy, food allergy, insect allergy, mold allergy, latex allergy, pet allergy, etc.

Q.5. What is anaphylaxis?
Ans: Anaphylaxis is a sudden, life-threatening immune system reaction. Certain allergic reactions develop anaphylaxis. Common allergens that may cause anaphylactic reactions include medications, insect stings, foods, and latex.

We hope this article on the Types and Symptoms of Allergies helps you in your preparation. Do drop in your queries in the comments section if you get stuck and we will get back to you at the earliest.