Generic Health Relevance

An allergic reaction is the hypersensitive response of the immune system to a usually harmless substance. Normally, the immune system will destroy a foreign substance, or antigen, without any outward signs or symptoms. However, sometimes the immune system overreacts and releases excessive antibodies in response to these antigens (allergens) triggering an inflammatory response in the body. Allergic reactions can happen to any one person at any time in his or her life for a wide variety of reasons. Common allergens are airborne (pollen, mold, dust mites), food (dairy, eggs, wheat), insect stings (bees, wasps), medications (penicillin), plants (poison ivy), and industrial products (latex). Allergies usually cause a person to have annoying and uncomfortable symptoms, like a runny nose, itchy eyes, or skin irritations. However, occasionally a person may suffer a severe allergic reaction known as anaphylaxis, a life-threatening form of shock.

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Allergens enter the body by being injected or absorbed into the skin, ingested, or inhaled into the lungs and the resulting symptoms can range from mild to severe. Allergies elicit a wide variety of symptoms that affect the respiratory system, the circulatory system, and the skin.

Respiratory System

  • Hoarseness
  • Itchy, runny nose and/or sneezing
  • Dry cough
  • Labored breathing
  • Wheezing

Circulatory System

  • Low blood pressure
  • Fast heartbeat
  • Pale skin
  • Dizziness
  • Loss of consciousness


  • Flushing, itching, or burning skin (especially the face and chest)
  • Hives
  • Swelling of face, neck, hands, feet, lips, and/or tongue
  • Warm, tingling feeling in the face, mouth, chest, feet, and hands

Other Symptoms

  • Anxiety
  • Abdominal cramps
  • Headache
  • Itchy, watery eyes


The prevalence of allergies has risen sharply since the Industrial Revolution with more than 50 million people reported to have allergies each year. Food allergies have also risen sharply, especially in children. According to the American Academy of Allergy, Asthma, and Immunology, up to 50% of all school-age children have reported sensitization to some type of food, resulting in an allergic response. Sensitization occurs when a substance triggers the immune system to recognize the substance as a threat to the body.

Allergic conjunctivitis. Inflammation of the conjunctiva (the mucous membrane covering the white part of the eye) causing redness, tearing, and itchiness.

Allergic rhinitis. Triggered by outdoor and indoor allergens. Results in itchy, watery eyes, swelling of nasal passages, congestion, and sneezing.

Asthma. Triggered by outdoor and indoor allergens causing inflammation of the lungs and constriction of the bronchial airways.

Eczema. A form of dermatitis characterized by dry, flaky skin found in patches on specific areas of the body (back of knees, elbow creases, etc.).

Food allergies. Triggered by food intolerance or insensitivity causing symptoms like rash, coughing, wheezing, swelling of face, tongue, or mouth, and hives.Insect venom allergy. An extremely dangerous allergic reaction caused by stinging insects that inject venom. This type of allergy often causes anaphylaxis.Skin contact allergy. Caused by direct contact with an allergen triggering swelling, redness, and blistering.

Risk Factors

Age. Food allergies are highly common in children. Studies show that exposure to allergens in infancy (like having a pet) can reduce the risk factor for developing allergies as an adult.

Chronic illness and weak immunity. Chronic autoimmune diseases and weak immunity increases a person’s risk for developing allergies due to a taxed immune system.

Environment. Highly polluted areas carry an abundance of noxious factors that can trigger an allergic response.

Genetics. An allergy is not inheritable. However, a tendency to have allergies can be carried from parent to child, especially if both parents have allergic conditions.

Smoking. Secondhand smoke is incredibly unhealthful and increases the risk for infants and children in developing respiratory illness and allergies.

Stress. High levels of stress hormones can cause the body to develop allergic symptoms like hives and skin rashes.


If you are concerned about having symptoms of allergies, seek professional help from an allergist. An allergist will ask for a detailed medical history and use allergy testing to identify the allergen source.

Medical history. Your medical history is particularly important because it gives your allergist the details of your behavior, the environment in which you live, and your family history – all factors that contribute to the development of allergies.

Skin test. These tests can identify a large number of suspected allergens, including food-related, contact, and airborne. There are three types:

  • Scratch – An allergen is placed in a liquid that is “scratched” on a section of the skin using a tool that barely punctures the liquid onto the surface. Your skin is closely watched to see if there is a localized reaction – redness, itchiness, or puffiness.
  • Intradermal – This test is ordered if the scratch test does not show clear results. The allergen is injected into the dermis layer of the skin and monitored for the same reaction as the scratch test.
  • Patch – The patch test involves the use of adhesive patches that are embedded with allergens and placed on patches of your skin. These adhesive patches are left on the skin and monitored at set intervals (48; 72; 96 hours) after application.

Blood test. If your allergist is concerned you will have a severe allergic reaction to a skin test, a blood test will be ordered. This blood test checks for the presence of circulating antibodies specific to the allergen itself. ImmunoCAP is a test method often used by allergists.

Elimination test. This is a simple food elimination diet test where common foods that cause allergic reactions are removed from the diet completely. The foods are added individually back into the diet to see which may be causing allergic symptoms.


The medical treatment for allergic diseases is designed around the medical history, the results of the allergy tests, and the severity of symptomatic response to the allergen of the patient suffering from the disease. The obvious first line of action is avoiding the allergen completely, especially if the patient is allergic to ingested substances, such as food and medications. Your allergist may recommend that you completely remove the source of the allergen from your home and limit exposure to airborne allergens when away from home.

Allergy Medications

Antihistamines. Block the trigger hormone, histamine, from causing an inflammatory response. Antihistamines are useful in treating the runny nose, itchiness, and redness of an allergic reaction, but may cause drowsiness.

Decongestants. Reduce stuffiness by shrinking the mucous membranes in the nose.

Epinephrine. Life-saving medicine used to treat the severe allergic reaction, anaphylaxis. This medicine comes in a self-injectable form known as an epi-pen. The shot must be administered quickly to reverse the reaction and a person who receives the shot needs to be taken to the hospital to make sure a secondary reaction does not occur again.

Nasal corticosteroids. Reduces swelling in people suffering from nasal allergies. These are nose sprays.

Mast cell stabilizers. Stops the release of histamine from mast cells. These eye drops or nose sprays help relieve itchy, watery eyes or an itchy, runny nose.

Oral corticosteroids. Prescribed by a healthcare professional to reduce inflammation and stop severe allergic reactions. These are corticosteroid medications that can cause serious side effects and must be closely monitored by your physician.

Immunotherapy Treatments

This treatment option involves the use of sublingual immunotherapy and allergy shots. Allergy shots are injections of a small amount of allergen into your body, with the dose increasing over time. These shots are effective for some patients who are allergic to pollen, dust, stinging insects, and asthma. Unfortunately, they are not as effective in treating people who have allergies to food, medicines, or have skin hypersensitivities.

Sublingual immunotherapy is a way to treat allergies without having to endure a shot. Allergists give patients a small dose of allergen under their tongues to build up a tolerance to the foreign substance and reduce symptoms. Sublingual immunotherapy is a safe alternative to injections and is administered to treat nasal allergies and asthma.

Alternative Treatments and Home Remedies

Alternative remedies for allergies can help relieve symptoms, act as natural antihistamines, and strengthen the immune system. You must be open with your healthcare provider about any supplements or herbal remedies you are using to avoid harmful interactions.

Vitamin C. Boosts the immune system and acts as a natural antihistamine. Studies show that vitamin C is an anti-inflammatory with the ability to reduce allergy symptoms when injected intravenously in high doses.

Bromelain. A natural enzyme derived from pineapples used to reduce swelling and inflammation and may have anti-allergic properties.

Probiotics. Beneficial microorganisms found in the gut known to strengthen the immune system and fights off allergies.

Quercetin. An antioxidant derived from many different plants and foods reported to reduce allergic symptoms and have antihistamine properties.


AAFA Medical Review. (2015, November). What are the symptoms of an allergy? Retrieved from Asthma and Allergy Foundation of America:

AAFA Medical Review. (2018, March). Allergy treatment. Retrieved from Asthma and Allergy Foundation of America:

American Academy of Allergy, Asthma & Immunology. Allergy statistics. Retrieved from AAAAI:

Doheny, K. (2009, April 23). Living with severe allergies. Retrieved from:

Galli, S.J., et. al. (2008, July 24). The development of allergic inflammation. Nature. Retrieved from:

Meng, J-F., and Rosenwasser, L. J. (2010, June 11). Unraveling the genetic basis of asthma and allergic diseases. Allergy, Asthma, & Immunology Research. Retrieved from:

Vollbracht, C., et al. (2018, June 27). Intravenous vitamin C in the treatment of allergies: an interim subgroup analysis of a long-term observational study. Journal of International Medical Research. Retrieved from Sage Publishing:

Mlcek, J., et al. (2016, May 12). Quercetin and its anti-allergic immune response. Molecules. 21(5). Retrieved from PubMed:


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