Allergy Overview – Symptoms, Causes and Its Treatment


The response of an immune system to the foreign invader is called Allergy. The term used to describe the foreign substance is known as Allergens. There is no specific type of allergens to your body. Many allergens are substances that are not harmful to most of the people, and they enter into our body when we inhale, eat, or touch them. However, when the immune system has an adverse reaction to a substance, it can be an allergen. 

What Causes an Allergic Reaction?

When the immune system overreacts to the allergen, it produces Immunoglobulin E (IgE) antibodies. An allergic reaction occurs when these antibodies reach histamine and other chemicals releasing cells. Atopy is described as the genetic tendency that develops allergic diseases. Atopic people get allergic inflammation due to the immune reaction when exposed to allergens. Symptoms may vary depending on the allergen like sneezing, inflammation, etc. allergic reaction triggers symptoms in the nose, throat, ears, lungs, sinuses, and lining of the stomach.

What are the Types of Allergens?

How and Why allergy develops? There is no definite answer to these questions. However, the development of allergy is either through the environment or genetics. The certain types of allergens that are allergic to the people are,

  • Dust and latex.
  • Pet dander.
  • Bee venom.
  • Pollen or molds.
  • Foods such as nuts or shellfish.
  • Medications such as aspirin or penicillin.

Affected Areas

Depending on allergen and from where it enters, the symptoms may vary.

1. Nose, Eyes, Sinuses & Throat

If allergens enter in while inhaling, the unleash of histamine induces the lining of the nose to produce mucus and become swollen. There might be symptoms like runny nose, violent sneezing, and itching. People may also experience sore throat and water in the eyes.

2. Stomach and Bowel

Few people can be allergic to certain food items like peanuts, dairy products, eggs, and seafood, which may affect their stomach. Infants may be allergic to cow’s milk, which causes asthma, eczema, and upset stomach.

3. Lungs and Chest

The lining of lung passage will bulge when you inhale the allergen. It leads to difficulty in breathing. An allergic reaction also triggers asthma.

4. Skin

Allergy disorders like urticaria and eczema will provoke skin problems.

What are the Allergy Symptoms?

The severity range differs according to the person’s immune system. The mild irritation signs are,

  • Skin rash and itching.
  • Nasal congestion.
  • Scratchy throat.
  • Watery eyes.
  • Hives.

Severe allergic reaction symptoms include,

  • Diarrhea, vomiting, nausea.
  • Nasal congestion, runny nose, itchy eyes.
  • Swelling of the tongue.
  • Wheezing, coughing, shortness of breath.
  • Drop-in blood pressure and dizziness.
  • Skin rash.
  • Unconsciousness.

The severe symptoms may be life-threatening or even leads to shock.

How can the Allergy be Diagnosed?

Doctors use allergens to recognize the type of allergies through testing. The tests include,

  • Skin Tests.
  • Challenge (elimination-type) Tests.
  • Blood Tests.
  • Patch Tests.

1. Skin Test

A drop of liquid that contains the substance you may be allergic to is placed on your forearm. Within 15 min if the skin feels itchy and red bump occurs, it means that you are allergic to the substance. The intake of Antihistamines before the test will interfere with the result.

Prick/puncture – Using the disposable plastic device allergens in a diluted form is pricked into your skin surface. If the results are negative, follow intradermal tests, which give more details about allergy symptoms.

Intradermal – Under the surface of the skin, a diluted allergen is injected using a thin needle. It specifies the causes of the symptoms.

A skin test is a valuable diagnosis for,

  • Venom allergy.
  • Food allergy.
  • Allergic contact dermatitis.
  • Penicillin allergy.
  • Pollen, mold, and animal dander allergy.

2. Challenge Testing

It is an effective method for diagnosing food allergy. During the test, the specialist will give you the food you suspect you are allergic to, and they will increase the amount gradually to check the reaction. It is a riskier test as the reaction can be severe, but it is an accurate way to diagnose food allergies. 

3. Blood Test

This test is required when skin test results are not possible or accurate. It measures IgE antibodies level in the immune system to specific allergens.

4. Patch Test

A patch test can discover contact dermatitis when the skin comes in contact with the allergen. In a special metal disc, a tiny portion of the suspected allergen is attached. For 48 hrs the disc is strapped around the skin and monitored.

What are the Treatments for Allergy?

Treatments for allergies can only soothe the symptoms, and it can’t be cured. 


Drugs are used to appease allergic symptoms in an emergency.

  • Antihistamines – When the immune system releases histamine during a reaction, antihistamines block them.
  • Decongestants – Relieves blocked nose.
  • Corticosteroids – Helps to reduce inflammation. It’s available in the form of a pill, nasal spray, inhaler, or cream.
  • Antileukotrienes – This medication blocks the chemicals that result in swelling.


It involves a gradual increase in doses of the substance to which the person is allergic. This procedure is performed under supervision by the specialist as there is a risk of a severe reaction. Treatment aims to make your body get adjusted to the allergen, which helps to reduce the severe reaction. Before starting treatment, the patient and allergists need to define the stimulating factors and type of allergens. It is suggested only when a patient is selectively sensitive to various allergens.

Allergic Disorders

There are several different allergy disorders as below:

Allergic Rhinitis (Hay Fever)

It refers to the nasal symptoms, and aeroallergens are the reason for this disorder. Symptoms include,

  • Postnasal drip (throat clearing).
  • Stuffy and runny nose.
  • Sneezing.
  • Itchy nose, ears, and throat.  


Hyperactivity or inflammation in airways, respiratory viral infections leads to asthma. The common signs are,

  • Coughing and wheezing
  • Chest tightness
  • Shortness of breath.

Eczema (Atopic Dermatitis)

Infants usually get this allergy. Direct exposure to an allergen is not a reason for this disorder. It occurs in people who have other allergic conditions like asthma or allergic rhinitis. Following are the feathers,

  • Dry skin and itching
  • Rashes found in the face, behind knees and elbows. 

Allergic Eyes (Conjunctivitis)

Inflammation of membranes covering the eyeball surface and under the surface of eyelid leads to allergic eyes. The signs include,

  • Swelling of the membrane.
  • Watery and itchy eyes.
  • Redness of eye and under the lids.

Hives (Urticaria)

A sign of red, itchy welts occurs due to skin reaction known as hives. It occurs over any part of the body. Chronic hives that recur for a longer period is rarely due to an allergic reaction. It is characterized by,

  • Intense itching.
  • Swelling (at face, lips, feet, and hand).
  • Red, raised welts.

Contact Dermatitis

When allergens come in contact with your body causes reaction, then contact dermatitis occurs. Symptoms include,

  • Dry skin and hives.
  • Rigorous itching.
  • Oozing blisters.
  • Red skin.
  • Swelling in the face, eyes, or groin areas.

Food Allergy

Intake of certain foods will show signs when they are inappropriate for the immune system by causing an abnormal response. Although symptoms may be similar to food intolerance, they are not the same. The symptoms include,

  • Diarrhea or vomiting.
  • Itching in the mouth.
  • Stomach ache.
  • Breathing trouble.
  • Asthma or hives.

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