Allergy is a common problem especially in the developed countries. In a research conducted in United States research it was noted that about 8% of the American children have some kind of food allergy.

How Allergic Reaction Occurs?

The person can be exposed to an allergen in a variety of ways such as inhalation, swallowing or contact with the skin. The first time the immune system sees an allergen, it responds by activating specialized cells called B cells. These cells make large amount of proteins called IgE antibodies. These antibodies attach to other immune cells called Mast cells making them sensitive to that particular antigen.

The next time the allergen enters the body these sensitive Mast cells quickly attack. They attach to the allergen and release the preformed chemicals such as Histamine. These chemicals can then cause the early symptoms of allergies. Then 4-6 hours later the mast cells release other chemicals (such as leukotorienes and prostaglandins and thromboxanes ). They are responsible for the symptoms such as redness and swelling in the affected area.

The diseases that  are mediated mainly by IgE antibodies include allergic rhinitis, skin allergy, asthma, allergy reactions to insect bites, drug allergy and food (peanuts) allergy.

What are the Symptoms of Allergy?

There are different parts of the body where the allergic reaction may occur such as skin, sinuses, nose, eyes, airways and gut. This is why signs and symptoms of an allergic reaction show great variation.

Inhaled allergens can produce following symptoms

• Sneezing
• Stuffy nose
• Runny nose
• Cough

An allergic reaction involving the skin is called Eczema and it could present with the following symptoms

• Rash
• Itching
• Flaring skin
• Peeling skin

 Food allergies can present with the following symptoms

• Vomiting
• Diarrhea
• Abdominal cramps
• Rectal bleeding

An allergic reaction to an insect or a drug can present with some or all of the following symptoms 

• Shortness of breath
• Restlessness
• Swollen tongue, lips and face
• Rash that is itchy and spreading often referred to as Hives

• Anaphylactic Reaction

It is a life-threatening allergic reaction. In anaphylaxis the allergen causes a generalized allergic response involving almost all the major systems of the body. The symptoms could be:

• Shortness of breath
• Hives
• Hypotension (Fall of Blood pressure )
• Heart attack or cardiac arrest

 

How Allergy is treated? 

There is no drug available to cure Allergy, but there are drugs that can help to relieve the symptoms of allergy. They include antihistamines, decongestants, steroids, bronchodilators, mast cell stabilizers and leukotriene inhibitors. The newer modality of treatment for the allergy is immunotherapy that is provided in the form of allergy shots.

 

Antihistamines

• They are the first line drugs used for the treatment of allergy. They include drugs such as Diphenhydramine (Benadryl), Cetrizine (Zytrec),  loratidine (Claritin), Desloratadine (Clarinex), and levocitrizine (Xyzal).
• In response to an allergic reaction specialized   immune cells in our body called Mast cells release different chemical. Histamine is once such important chemical. It is responsible for different symptoms of allergy such as stuffy nose, sneezing, runny nose, red itchy eyes, itching and rash of the skin. Antihistamine blocks the histamine from acting on its receptor, thus preventing these symptoms.
• They are usually safe. The commonly noticed side effect with antihistamines is sedation. This can be successfully addressed by taking antihistamines just before bedtime or by using newer non-sedative antihistamines. The other problems noted with these drugs are dryness of mouth and blurring of vision.

Decongestants

• In response to an allergic reaction blood vessels in nose and eyes dilate, increasing the blood flow to these organs. This can result in the symptoms such as stuffy nose and redness of the eyes.
• Decongestants cause the constriction of these dilated blood vessels.  This decreases the blood flow to the nose and eyes, thus reliving the symptoms of congestion.
• They include drugs such as Pseudoephedrine (Sudafed), and Ephedrine.
• Decongestants can produce some serious side effects such as hypertension, glaucoma. The minor side effects noted with these medications are restlessness and irritability.

Steroids

• They are anti-Inflammatory medications. They work by decreasing the inflammation associated with allergy.
• They are available in different form such as nasal sprays, eye drops.  The oral as well as topical preparations are also available. They are used in the inhaled forms to relieve the respiratory symptoms associated with allergies.
• They can cause serious side effect especially when given in high doses, systemically and for longer period of times. The potential side effects of long-term steroid therapy include weight gain, high blood pressure, cataract, diabetes and osteoporosis.

Bronchodilators

• They are used to treat respiratory problems such as asthma. They are available in both short acting as well as long acting forms. They include drugs such as salbutamol, and salmetrol .
• They can increase the heart rate and result in high blood pressure as side effects.

Mast cell stabilizers

• They are mainly used to prevent the attacks of symptoms. They are also used in the treatment of nasal allergies.
• They work by inhibiting the release of chemical mediators such as Histamine from the mast cells.
• They include drugs such as Cromolyn and Nadocromolyn.
• The side effects noticed with mast cell stabilizers are bad taste and blurring of vision.

Leukotriene Inhibitors

• They are mainly used to treat asthma and nasal allergy
• They include drugs such as Zafirlukast and Montelukast.
• They work by blocking the actions of Leukotrienes, chemicals mediating the allergic reaction.
• The rare side effects noticed with Leukotriens are rash, cough, stuffy nose, fever and heartburn.

Allergy Shots/immunotherapy

This is a newer modality of treatment of allergy. They are used when the allergy cannot be controlled with the conventional anti-allergic drugs. The allergy shots are made up of small amounts of the allergens such as pollens, pet dandruff, and dust mites. They work by desensitizing you against these allergens.