Anaphylaxis is your body’s response to antigens, exhibiting an allergic reaction. Health experts emphasize on immediate treatment to prevent anaphylactic shock.

Allergies

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ZAKA CLINIC GULBERG LAHORE

Saad Ullah Siddiqui

Overview

<p dir="ltr">An allergy is a response of the body&rsquo;s immune system to foreign substances which normally do not illicit a harmful response. These foreign substances are referred to as allergens and range from certain foods to pet dander and pollen etc<sup><a href="#accordion">[1]</a></sup>.</p>

<p dir="ltr">The immune system keeps the body healthy by fighting against pathogens. It attacks any foreign substance that is potentially harmful to the body. Moreover, the response for example, sneezing, inflammation, hives, etc., depends on the allergen.&nbsp;</p>

<p dir="ltr">Your immune system is vulnerable to environmental triggers; however, it does not react to harmless triggers e.g. pet dander. This, unfortunately, is not the case for allergy-prone individuals. Their immune systems perceive pat dander as harmful and threatening to the body, thereby attacking it.</p>

<p dir="ltr">Generally, allergies are very common, and doctors prescribe certain medications to treat the symptoms.</p>

<p>&nbsp;</p>

<h5><strong>What Happens During An Allergic Reaction?</strong></h5>

<p>An allergic reaction starts when your body encounters the triggers either through inhalation, swallowing, or dermal contact. In response to the triggers, the body starts making the protein IgE that grabs the allergen. Furthermore, histamine and other chemicals are released in the blood, which causes allergic symptoms.<br />
&nbsp;</p>

<h5><strong>Prevalence</strong></h5>

<ul>
	<li>According to the annual US National Health Interview, in 2010, 17.9 million adults were diagnosed with hay fever (allergic rhinitis), i.e. 7.8% of the population of the country was affected.</li>
	<li>The yearly diagnosis in children is more frequent compared to adults, with approximately 7.1 million children (9.5 %) being diagnosed with allergies.</li>
	<li>8.6 million children reported having respiratory allergies between a period of 1-2 months in 2010.</li>
	<li>A study cited among the Pakistani population revealed that 19.6% of individuals have allergic asthma. The sensitization to various inhalant allergens was pollen 20.3%, paper mulberry 20.3%, HDM 20.3%, thresher 20.2%, and raw cotton 17%<sup><a href="#accordion">[2]</a></sup>.&nbsp;<br />
	&nbsp;</li>
</ul>

<h5><strong>What Are The Common Allergens?</strong></h5>

<ul>
	<li>Animal products, including pet dander, cockroaches, and dust mite waste</li>
	<li>Drugs that include penicillin and sulfa drugs</li>
	<li>Foods, for example, wheat, milk, nuts, and egg</li>
	<li>Insect bites and stings, including from&nbsp;bees, wasps, mosquitoes, and spiders</li>
	<li>Airborne mold spores</li>
	<li>Plants, including trees, grass, weeds, and plant resin; poison ivy and poison oak are common plant allergens</li>
	<li>Other allergens consist of latex gloves, condoms, metals like nickel, etc.&nbsp;<br />
	&nbsp;</li>
</ul>

<h5><strong>Seasonal Allergies</strong></h5>

<p>The most common seasonal allergy is hay fever caused by pollen released from the plants. The symptoms include the following:</p>

<ul>
	<li>Watery eyes</li>
	<li>Itchy eyes</li>
	<li><a href="https://merisehat.pk/disease/cold-flu">Coughing</a></li>
	<li>Runny nose<br />
	&nbsp;</li>
</ul>

Signs And Symptoms

<p dir="ltr">The symptoms of allergy depend on the allergen: airborne, dermal, food, or insect bite.&nbsp;Nasal allergy is triggered when you inhale allergens that have the following symptoms:</p>

<ul>
	<li>Watery and itchy eyes</li>
	<li>Sneezing</li>
	<li>Runny and itchy nose</li>
	<li>Lethargy and illness<br />
	&nbsp;</li>
</ul>

<p dir="ltr">Some of the common symptoms of skin allergy are rashes and hives (urticaria). Your skin may become red, itchy, and swollen.&nbsp;</p>

<p dir="ltr">Food allergies can cause stomach cramps, nausea, vomiting, and diarrhea.&nbsp;Insect sting triggers can cause swelling, redness, and pain in the area where you have been stung. The symptoms can range from mild to severe; however, most of the symptoms settle down once the cause is eliminated.&nbsp;&nbsp;</p>

<p>&nbsp;</p>

<p dir="ltr">Range of symptoms:</p>

<ul>
	<li>Mild symptoms are usually quite unnoticeable and would just make you a little worse for wear.</li>
	<li>Moderate symptoms can make you feel slightly worse, and you may also get a cold or flu.</li>
	<li>Severe allergic reactions are rare, but extreme, and require immediate medical attention.<br />
	&nbsp;</li>
</ul>

<h4><strong>Anaphylaxis</strong></h4>

<p>Severe allergic reactions are called anaphylaxis and the whole body is affected. The symptoms include the following:</p>

<ul>
	<li>Itching and hives all over the body</li>
	<li>Shortness of breath and wheezing</li>
	<li>Hoarseness and tightness in the throat</li>
	<li>Swelling of the face, lips, throat, and eyelids</li>
	<li>Tingling sensation in the hands, feet, scalp, and lips</li>
</ul>

<p dir="ltr">Anaphylaxis is a threat to life. Epinephrine injections should be used immediately. However, since they&rsquo;re not easily available over the counter in Pakistan, the affected individuals should seek immediate help from their nearest hospital.<br />
&nbsp;</p>

<h4><strong>Underlying Mechanisms Of Action Of Allergies</strong>&nbsp;</h4>

<p dir="ltr">The most common cause of allergies is the hypersensitivity of the <a href="https://www.merisehat.pk/article/how-an-over-prescription-of-antibiotics-affects-your-immune-system">immune system</a>. Various allergic reactions are apparent due to different underlying mechanisms at play, for example, allergic reactions can be Immunoglobulin E (IgE) mediated or due to the production of immunoglobulins IgM or IgG, etc. Delayed allergic reactions are often mediated by T cells.<br />
&nbsp;</p>

Causes

<p dir="ltr">Immunoglobulin E (IgE) mediates type 1 hypersensitivity reactions, e.g. reactions to bee stings, drugs (penicillin), and certain foods (nuts, fish etc). The allergen binds to the antibodies in the white blood cells (basophils and mast cells), causing a release of chemicals (histamine and leukotrienes) which manifests as an allergic reaction.&nbsp;</p>

<p dir="ltr">These reactions include hives, skin rash, runny nose, sneezing, nausea, diarrhea, and other serious symptoms like swelling of the tongue, throat, and lips or even an asthma attack. Anaphylaxis is the most serious form of an allergic reaction, which can be life-threatening and requires immediate medical attention.</p>

<p dir="ltr">The symptoms depend on the part of the body exposed to the allergen. For example, inhalation of pollen can cause nasal allergies, while food-associated reactions are more widespread.&nbsp;&nbsp;<br />
&nbsp;</p>

<h5><strong>Airborne Allergens</strong></h5>

<p dir="ltr">40% of the allergies in children are due to airborne allergens. The most common allergens include mold, weeds, grass, dust mites, pollen, grass, and pet dander.<br />
&nbsp;</p>

<h5><strong>Foods</strong></h5>

<p dir="ltr">A lot of children in Pakistan have food allergies, but most are unaware of them due to a lack of exposure and resources. Allergic reactions to food occur within seconds or minutes of consuming the food. It is rarely delayed to a few hours. The reactions cause gastrointestinal, skin, nasal, and cardiovascular symptoms in addition to anaphylaxis. Moreover, few people can also experience a second anaphylactic reaction, hours after the first one.</p>

<p dir="ltr">Allergic reactions are usually triggered by the following foods:</p>

<ul>
	<li>Milk</li>
	<li>Peanuts</li>
	<li>Eggs</li>
	<li>Wheat</li>
	<li>Fish<br />
	&nbsp;</li>
</ul>

<h5 dir="ltr"><strong>Medications</strong></h5>

<p dir="ltr">Reactions to medications vary and can affect different parts of the body e.g. hives and other rashes, gastrointestinal reactions, <a href="https://merisehat.pk/disease/whopping-cough">coughing</a>, itching, and wheezing. Some of the most common drugs that can cause an allergic reaction include non-steroidal anti-inflammatory drugs (NSAIDs), antibiotics, anti-seizure medications, biological medications, and chemotherapy. Certain drugs, such as&nbsp;ACE inhibitors, make patients more allergic by enhancing sensitivity to histamine.</p>

<p>&nbsp;</p>

<h5><strong>Insect Bites</strong></h5>

<p dir="ltr">The following insect bites can cause severe allergic reactions in some people:</p>

<ul>
	<li>Mosquito bites</li>
	<li>Bee stings</li>
	<li>Bed bug bites&nbsp;</li>
	<li>Fire ant stings<br />
	&nbsp;</li>
</ul>

<h5><strong>Contact Allergens&nbsp;</strong></h5>

<p dir="ltr">Contact allergens cause delayed Type IV reactions mediated by T lymphocytes.</p>

<p dir="ltr">Examples of chemical irritants include but are not limited to, poison ivy, sumac, oak, nickel, skincare products, makeup, fragrances, hair dyes, latex, antibacterial ointments, formaldehyde, and leather tanning chemicals.</p>

<p dir="ltr">A profound example of Type IV allergic reaction is the Steven Johnson Syndrome, which involves the skin and mucous membranes.<br />
&nbsp;</p>

<h5><strong>Genetics</strong></h5>

<p dir="ltr">Genetics do play a role in allergies because allergic tendencies are often inherited. You can be at a higher risk if an allergy is common in your ancestors. It means that you are atopic, and your body is more likely to be at threat of new allergens.&nbsp;</p>

<p dir="ltr">Researchers are still working on identifying the genes that cause allergies and make people susceptible to allergic diseases. However, your genes are not the only determining factor since the environment also plays an important role in triggering allergies.&nbsp;</p>

<p dir="ltr">A thorough family history can be useful to determine whether your allergic symptoms are genetic, for example, maternal and paternal history of asthma is often inquired when a child presents with wheezing.&nbsp;&nbsp;<br />
&nbsp;</p>

<h5><strong>Lifestyle</strong></h5>

<p dir="ltr">Theories say that exposing infants to allergens, for example, pets in the house and allergic infections can prevent them from developing allergies (hygiene hypothesis). However, the hypothesis has yet to be considered conclusive.&nbsp;</p>

<p dir="ltr">Preventive measures can be adopted to reduce the incidence of allergies, for example, children&rsquo;s bedding can be covered with impermeable covers to reduce their exposure to dust mites, or regular room cleaning to ensure homes are dust free. Breastfeeding is also recommended to boost the infant&rsquo;s immune system.</p>

<p dir="ltr">Mothers who are smokers and also smoke during pregnancy increase their child&rsquo;s risk of allergies. Passive smoking also places infants and children at a higher risk of developing allergies.<br />
&nbsp;</p>

<p dir="ltr">If you suffer from allergies, avoid encountering the triggers that will cause a reaction. Avoid keeping pets in your house and reduce outdoor activities during the pollen season. Consume processed and packaged food with care and avoid wearing artificial jewelry, or jewelry that consists of nickel.<br />
&nbsp;</p>

Treatment

<p dir="ltr">Allergy has no cure, but several medications are available for symptomatic management. These medications include antihistamines, decongestants, corticosteroids, and decongestants to name a few. For patients suffering from moderate to severe allergies, immunotherapy (allergy shot) is available. It helps in improving the immune system&rsquo;s tolerance e.g. flu vaccine.</p>

<p dir="ltr">&nbsp;</p>

<h5><strong>Antihistamines</strong></h5>

<p dir="ltr">Antihistamines are considered the gold-standard drugs to treat allergic reactions. They can be taken in the form of pills, nasal sprays, liquids, and eye drops. These are readily available over the counter and can help ease watery and itchy red eyes. Whilst, nasal sprays can treat seasonal/annual allergy symptoms.</p>

<p dir="ltr">Following are some examples of antihistamines:<br />
&nbsp;</p>

<p dir="ltr"><strong>Over-The-Counter Antihistamines</strong></p>

<p dir="ltr">Taken Orally:</p>

<ul>
	<li>Cetirizine</li>
	<li>Fexofenadine</li>
	<li>Levocetirizine</li>
	<li>Loratadine<br />
	&nbsp;</li>
</ul>

<p dir="ltr">With Sedatives:</p>

<ul>
	<li>Brompheniramine</li>
	<li>Chlorpheniramine</li>
	<li>Clemastine</li>
	<li>Diphenhydramine<br />
	&nbsp;</li>
</ul>

<p dir="ltr">Eye Drops:</p>

<ul>
	<li>Ketotifen</li>
	<li>Naphazoline and Pheniramine</li>
</ul>

<p dir="ltr">&nbsp;</p>

<p dir="ltr"><strong>Prescription Medication</strong></p>

<p dir="ltr">Taken Orally:</p>

<ul>
	<li>Desloratadine<br />
	&nbsp;</li>
</ul>

<p dir="ltr">Nasal Spray:</p>

<ul>
	<li>Azelastine<br />
	&nbsp;</li>
</ul>

<p dir="ltr">Eye Drops:</p>

<ul>
	<li>Azelastine Ophthalmic</li>
	<li>Epinastie Ophthalmic&nbsp;</li>
	<li>Olopatadine Ophthalmic</li>
</ul>

<h4>&nbsp;</h4>

<h4><strong>Mechanism Of Action Of Antihistamines</strong></h4>

<p dir="ltr">People with allergies have an exaggerated immune response to otherwise harmless triggers. Mast cells, which are immune system cells, release a substance called histamine that is attached to the receptors in the blood vessels, making them enlarged. Furthermore, histamine also binds to other receptors, which causes swelling, redness, itching, and increased secretions. Antihistamines prevent these symptoms by blocking histamine and preventing it from binding to various receptors.<br />
&nbsp;</p>

<h4><strong>Side Effects Of Antihistamines&nbsp;</strong></h4>

<p dir="ltr">Over-the-counter antihistamines can cause drowsiness. However, other newer antihistamines don&rsquo;t make you drowsy and can be bought either over the counter or by prescription.<br />
&nbsp;</p>

<h4><strong>Decongestants</strong></h4>

<p dir="ltr">Decongestants are prescribed alongside antihistamines and relieve congestion. They are available in the form of nasal sprays, syrups, pills, and eye drops.&nbsp;</p>

<p dir="ltr">Nasal sprays and eye drops are recommended to be used only for a few days and not for the long term because they can worsen symptoms. Pills and decongestants can be taken safely for a longer period.</p>

<p dir="ltr">Following are some examples of decongestants:</p>

<ul>
	<li>Phenylephrine and Oxymetazoline</li>
	<li>Pseudoephedrine</li>
	<li>Visine eye drops</li>
</ul>

<h4>&nbsp;</h4>

<h4><strong>Mechanism Of Action Of Decongestants</strong></h4>

<p dir="ltr">The tissues in your nose swell as a response to an allergic reaction from an allergen, making the fluid mucus. The blood vessels in the eyes can also well and cause redness. Decongestants shrink the swollen nasal tissues and blood vessels. They relieve the symptoms of congestion, nasal swelling, mucous secretion, and redness.</p>

<p>&nbsp;</p>

<h4><strong>Side Effects Of Decongestants</strong></h4>

<p dir="ltr">Decongestants can cause high blood pressure; hence, are not recommended in people with <a href="https://merisehat.pk/disease/hypertension">high blood pressure</a> (hypertension) and glaucoma. Additionally, decongestants can cause insomnia, restricted urinary blood flow, and irritability.</p>

<h4>&nbsp;</h4>

<h4><strong>Combination Allergy Drugs</strong></h4>

<p dir="ltr">Some allergy drugs are a combination of antihistamines and decongestants that relieve the symptoms of multiple allergies. These have multiple modes of action alongside blocking histamine, for example, prevention of mast cells from releasing other chemicals that induce allergies.</p>

<h4>&nbsp;</h4>

<h4><strong>Anticholinergic Nasal Sprays</strong></h4>

<p dir="ltr">Ipratropium bromide is an anticholinergic drug that reduces symptoms of a runny nose. When the user sprays it into each nostril, it decreases mucus production from the glands that line the nasal passages.</p>

<h4>&nbsp;</h4>

<h4><strong>Side Effects Of Ipratropium</strong></h4>

<p dir="ltr">Anticholinergic sprays can cause dryness of the nose which can lead to epistaxis (nose bleeds) and irritation. Headache, upset stomach, stuffy nose, and sore throat are other side effects to watch for.</p>

<h4>&nbsp;</h4>

<h4><strong>Steroids</strong></h4>

<p dir="ltr">Steroids reduce allergy-associated inflammation and treat and prevent nasal stuffiness, sneezing, and itchy or runny nose, which could be caused due to either seasonal changes or are present annually. Additionally, they can also decrease inflammation and swelling due to other types of allergic reactions.&nbsp;</p>

<p dir="ltr">Systemic steroids are available in the form of pills or liquids e.g. locally acting inhalers for asthma, locally acting nasal sprays for seasonal or all-year allergies, topical creams for allergic conjunctivitis, and topical creams for skin allergies. Other than steroids, your physician may prescribe you additional medications to help combat allergic symptoms.</p>

<p dir="ltr">Steroids are very effective for treating allergies and need to be taken regularly to be effective.</p>

<p dir="ltr">Following are some of the types of steroids:</p>

<ul>
	<li>Prescription nasal steroids</li>
	<li>Over-the-counter nasal steroids</li>
	<li>Eye drops</li>
	<li>Oral steroids</li>
</ul>

<h4>&nbsp;</h4>

<h5><strong>Side Effects Of Steroids</strong></h5>

<p dir="ltr">When steroids are taken for a longer period, they may cause side effects. When used for a short period, the most common systemic side effects are weight gain and high blood pressure. Long-term side effects of systemic steroids include growth retardation, <a href="https://merisehat.pk/disease/diabetes-type-1-and-2">diabetes</a>, <a href="https://merisehat.pk/disease/cataract">cataracts</a> (eyes), muscle weakness, and bone-thinning <a href="https://merisehat.pk/disease/osteoporosis-80">osteoporosis</a>. The side effects of inhaled steroids may include hoarseness, cough, and fungal infections of the mouth.</p>

<h4>&nbsp;</h4>

<h5><strong>Mast Cell&nbsp;</strong><strong>Stabilizers</strong></h5>

<p dir="ltr">Mast cell stabilizers are the mainstay treatment for mild to moderate inflammation and are easily available in the form of eye drops for allergic conjunctivitis and nasal sprays for allergic symptoms. Although, just like any other drugs, mast cell stabilizers take several weeks before being effective.</p>

<h4>&nbsp;</h4>

<h5><strong>Mechanism Of Action Of Mast Cell&nbsp;</strong><strong>Stabilizers</strong></h5>

<p dir="ltr">Mast cell stabilizers prevent mast cells from releasing histamine. Although they are not as effective as steroids, they do offer important anti-inflammatory effects.</p>

<h4>&nbsp;</h4>

<h5><strong>Side Effects Of Mast Cell&nbsp;</strong><strong>Stabilizers</strong></h5>

<p dir="ltr">Side effects include irritation of the throat and skin rashes. Mast cell stabilizers, in the form of eye drops, may cause burning, blurred vision, and stinging.</p>

<h4>&nbsp;</h4>

<h5><strong>Leukotriene Modifiers</strong></h5>

<p dir="ltr">Asthma and nasal allergies are treated with leukotriene modifiers. Doctors prescribe them with other drugs which are available in the form of pills, chewable tablets, and oral granules.&nbsp;</p>

<p dir="ltr">Singulair is the only leukotriene modifier that is FDA-approved.</p>

<h4>&nbsp;</h4>

<h5><strong>Mechanism Of Action Of Leukotriene Modifiers</strong></h5>

<p dir="ltr">Leukotrienes are chemicals produced by the body in response to allergic reactions and leukotriene modifiers block their production.</p>

<h4>&nbsp;</h4>

<h5><strong>Side Effects of Leukotriene Modifiers&nbsp;</strong></h5>

<p dir="ltr">The side effects of leukotriene modifiers include the following:</p>

<ul>
	<li>Stomach cramps and upset stomach</li>
	<li>Acidity and <a href="https://merisehat.pk/disease/heart-burn-58">heartburn</a></li>
	<li>Fever</li>
	<li>Rash</li>
	<li>Stuffy nose</li>
	<li>Cough</li>
	<li>Headache</li>
	<li>Irritability</li>
</ul>

<h4>&nbsp;</h4>

<h5><strong>Other Over-the-Counter Products</strong></h5>

<p dir="ltr">Some over-the-counter home remedies can treat allergic reactions, which include the following:</p>

<ul>
	<li>Normal saline or saltwater solution is also available in the form of nasal sprays to treat mild congestion, crusting, and loosening mucus. These sprays do not contain any medication.</li>
	<li>Artificial tears can also be used, which do not contain any medication either. They can treat itchy, watery, and red eyes.</li>
</ul>

<h4>&nbsp;</h4>

<h5><strong>Immunotherapy</strong></h5>

<p dir="ltr">Immunotherapy is a very effective treatment option for people who suffer from allergies for longer than three months in a year. Allergy shots expose you to increased levels of allergens, helping your immune system to build and maintain tolerance against allergens.</p>

<p dir="ltr">Example: Odactra relieves the symptoms of allergies to dust mites, and Palforzia treats peanut allergy.<br />
&nbsp;</p>

Key Points

<ul>
	<li>An allergy happens when the body encounters a harmful substance and overreacts.</li>
	<li>The substance that causes allergic reactions is called an allergen.</li>
	<li>The immune system makes IgE antibodies in response to allergens.</li>
	<li>The most common symptoms of allergies are watery eyes, hives, rashes, and sneezing.</li>
	<li>The treatment of allergy is based on your medical history and the severity of the symptoms.<br />
	&nbsp;</li>
</ul>

[1] Raab, W., 1989. Practically important allergies. An overview. Wiener Medizinische Wochenschrift (1946), 139(6-7), pp.108-115.

[2] Khan, S.W., Hamid, A., Siddiqi, F.A. and Bakhtawar, M., 2018. Frequency of allergic asthma and common aeroallergens sensitization in Pakistani patients of bronchial asthma. Journal of the Pakistan Medical Association, 68(8), pp.1217-1221.

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