Allergy

Allergies are some of the most common conditions seen worldwide. Allergy symptoms can be mild or in some people, they can even be life-threatening. What was considered a rare disease at the beginning of the 20th century, allergies have emerged as a growing health problem in the recent past. Studies show that almost 20% of the European population affected with allergies struggle in their daily life with the fear of an asthmatic or anaphylactic attack or even death from exposure to a triggering agent. The World Allergy Organization estimates that between 10 to 40% of any country’s population is affected by allergy disorders. In a person, allergies usually manifest at the peak of their lives, due to which they lose a lot of daily time. In India too, the burden of allergies has been steadily rising. It is reported that 20 to 30% of the total Indian population suffers from allergies consisting of asthma, rhinitis, food allergy, eczema, urticaria, anaphylaxis and angioedema.

What are allergies?

An allergy is a disorder of the immune system in which the immune system becomes hypersensitive. It is a reaction by the body’s immune defences to any agent which otherwise is harmless to most people. In healthy people, the immune system fights against any germ, however, in people with allergies, the immune system over-reacts to a non-germ agent, also known as an allergen. People who have allergies are usually sensitive to more than one type of substance. Environmental and genetic factors both play an important role in allergic diseases.

There are several types of allergies, which include:

• Dust allergy
  Dust allergies are caused by dust mites which are tiny microscopic organisms that are present in house dust and air moisture. As it is one of the most common allergens, its symptoms are seen all year round. Along with rhinitis, dust allergies can also trigger symptoms of asthma and eczema. More often, these symptoms are aggravated during vacuuming, sweeping or dusting as these processes cause the dirt particles to rise up making them easy to be inhaled.
• Allergic Rhinitis
  Commonly known as hay fever, allergic rhinitis develops when the body’s immunity overreacts to harmless substances in the environment. Allergic rhinitis can be seasonal, often occurring during spring, summer and early fall due to pollens or spores. It can also be perennial wherein people can experience symptoms all around the year.
• Skin allergies
  There are several types of skin allergies. These include:
  • Eczema
    Also known as atopic dermatitis, it is common in children, and to a lesser extent in adults. People with eczema often have a positive history of allergy.
  • Hives
    Hives or urticaria are red swellings that appear on the skin. Acute hives are common after an exposure to an allergen or infections. If the urticaria lasts for more than 6 weeks, it is said to be chronic. The exact cause of chronic urticaria is widely unknown.
  • Contact dermatitis
    Contact dermatitis is a condition in which the skin comes in contact with an allergen or an irritating substance. Soaps, detergents, metals, latex gloves are some of the items that can cause contact dermatitis. In some people, there won't be any reaction on the skin unless the skin is exposed to sunlight. This is called photoallergic contact dermatitis. It can be seen with lotion, sunscreens and even perfumes.
• Insect bite and pet allergy
  Majority of the people are not allergic to insect bites. But it has been known that insect stings can lead to life-threatening allergic reactions that can even lead to deaths. Bee stings are very common in tropical countries. Studies have estimated that hypersensitive allergic reactions, known as anaphylaxis caused due to bee stings are seen in 1% of children and 3% in adults. Allergic reactions from pets can be seen after petting or playing with the cat or dog.
• Food allergy
  According to the Centers for Disease Control (CDC), approximately 4 to 6 % of children and 4% of adults have food allergies. Though symptoms of food allergy are common in children and babies, they can appear at any age. A person may develop food allergies to foods which they have well tolerated for many years without problems.
• Drug allergy
  If a person develops a rash or experiences shortness of breath after taking certain medicines, they may have a drug allergy. Similar to other types of allergic reactions, such symptoms are seen when the immune system gets sensitized to a particular drug, the body perceives as a foreign substance and releases chemicals against it.

Symptoms of different types of allergy include:

Dust allergy

• Running or stuffy nose.
• Sneezing.
• Red, watery eyes with itching.
• Coughing, wheezing with tightness in the chest. (Read more - Chest pain causes)

Allergic rhinitis

• Runny or stuffy nose.
• Itching in the eyes and skin.
• Sneezing.
• Exhaustion and tiredness due to poor sleep caused by nasal obstruction.

Skin allergies

Common symptoms of skin allergy include redness, itching and swelling. There are some minor differences that can help to diagnose specific skin conditions.

• Eczema and contact dermatitis
  People with eczema often have dry and itchy skin with crusts. In some people the crust may ‘leak’ releasing a fluid when scratched, indicating an infection. In children, eczema involves the face, bends of joints and behind ears. Adults have eruptions in similar locations and also on hands and feet. In contact dermatitis, similar symptoms are seen at the point of contact of the allergen or metal.
• Urticaria
  In urticaria, the skin is red, inflamed and shows red raised bumps that vary in size and can appear on any part of the body. A condition called angioedema, wherein the deeper layers of the skin are affected may also be present. It may be seen around the eyes, lips or cheeks. Sometimes, it may also be present in genitals or inside of throat or bowels.

Insect and pet allergy

Symptoms of pet allergy are similar to dust allergy, and they appear after exposure to an animal. Symptoms of insect allergy include:

• Swelling of face, lips, throat and tongue.
• Difficulty in breathing.
• Itching and urticaria rash at the site of sting followed by a small blister filled with pus-like material.
• Nausea and vomiting
• Stomach cramps.

Food allergy

Symptoms of food allergy can occur right after eating or several hours later. They include red, itchy skin, stuffy nose, nausea, vomiting, cramps and diarrhoea. In some people, food allergies can lead to a severe condition called anaphylaxis which includes:

• Tightness in the chest.
• Swelling of the tongue, throat and lips.
• Tingling of hands and feet.

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Allergies have multiple causes and triggers. These include:

Causes

• Triggers of dust and pet allergy are:
• Dust mite
• Mould
• Pollen
• Cockroaches
• Pet hair, fur, feathers

Triggers of hay fever or allergic rhinitis are:

• Indoor allergens like dust mites, mould, pet hair or dander
• Outdoor allergens like pollen, spores
• Certain irritants like perfumes, smoke, petrol or diesel exhaust

Causes of skin allergies

• Eczema is linked to the presence of faulty genes and environmental conditions. It is often linked with asthma, food allergies and hay fever.
• Urticaria is triggered by eating a particular food or some specific allergen. It may also be triggered by heat, exercise, foods, medications, insect stings or infections.
• Contact dermatitis is caused by coming in contact with irritants like soaps, detergents, shampoos, metals like nickel, steel, adhesives, plants, latex gloves, and other topical medications.

Triggers of insect allergy are:

• Honey bees, wasps, hornets, fire ants, yellow jackets
• Food allergies are usually caused by:
• Eggs
• Milk
• Peanuts
• Shellfish
• Wheat
• Soy
• Fish
• Tree nuts

Drug allergies may be caused due to:

• Penicillin and other derivatives
• Antibiotics
• Aspirin, ibuprofen
• Nonsteroidal anti-inflammatory drugs (NSAIDs)

Risk Factors

The incidence of allergy disorders is on a steady rise. The exact reason is not yet found, but there are theories explaining the rise in allergic rhinitis and asthma. These risk factors include:

• High exposure to dust, mites
• Environmental pollution
• Nutritional changes
• Unhealthy  lifestyle
• Children whose mothers are smokers
• Diesel fumes
• Family and genetic history is said to be a strong factor for the development of asthma
• Sensitization to allergens is linked with atopic dermatitis (Eczema).

A proper allergy management plan is the best way to prevent allergies. Controlling the symptoms of allergy depends on the type of allergy. Some ways to manage allergies include:

• Avoid exposure to the allergen
  This is an important factor in preventing symptoms. Many times it is not easy, but it is the best way to minimize exposure or contact.
• Take medications immediately
  The best method to manage symptoms is to take anti-allergy or antihistamines to relieve pain and swelling.
• Keep a diary
  It is best to track what one eats, to know what symptoms may occur and what may help. This information is also useful to the doctor in determining a diagnosis.

To arrive at a complete diagnosis, the doctor will take the following steps:

• The doctor will take down a complete medical history to arrive at a complete understanding of a person’s symptoms and the triggering agents that cause the reactions. If the person is maintaining a diary, it is advised to bring notes to help the physician. Questions related to past and family history will be asked to know the risk factors for allergies.
• A thorough physical examination is conducted by examining the person’s eyes, nose, ears, throat, skin to look for signs of allergic reactions.
• Certain blood tests will be performed to confirm the diagnosis. There is no specific test that can accurately confirm the type of allergy. These tests only help the doctor in establishing a diagnosis.
  • IgE tests are carried out to measure the number of antibodies released by the body against an allergen. This is not a very sensitive test as it may not determine the severity of the allergy.
  • Skin prick test is advised to look for the sensitivity to a particular substance. The greater the reaction seen in 15 minutes, the higher the sensitivity to the substance.
  • Patch test determines the substance causing contact dermatitis. An allergic response seen within 48 to 96 hours corresponds to a positive test.

Allergy treatment depends on the medical history, severity of symptoms and results obtained from allergy tests. It is carried out in the following steps:

• Avoiding allergen
  The best way to avoid allergy is to avoid or reduce the exposure to the triggering agent. This helps to reduce the need for medications as well as removing the source. Airborne allergens can be reduced by regular nasal irrigation using a "jal neti" pot or a squeeze bottle.
• Medications
  Anti-allergic medicines like antihistamines along with decongestants help in reducing the swelling seen in allergies. Antihistamines block the release of histamine, a chemical released during allergic reaction which prevents a runny or stuffy nose. Decongestants shrink the swollen membranes of the nose and reduce swelling. Corticosteroids for skin complaints halt the spread of rashes.
• Immunotherapy
  In some people,  immunotherapy is advised. These include people with pollen, pet, insect allergies and asthma. This therapy helps to improve exposure to allergens and tolerance along with a reduction in symptoms. Immunotherapy is not yet proven to be useful for food allergies, though several studies are been conducted for its effectiveness.

Lifestyle management

It is best to avoid allergies through proper management. A close working relationship with the doctor can help in managing allergic reactions. Avoiding exposure to allergens can limit occurrences and limit the point of source. If the person is at risk of developing severe reactions, keep epinephrine injections at all times. It is the only treatment for severe allergic reactions and is provided only when it is prescribed by a doctor. People with such allergies are also advised to wear a medical alert bracelet in cases of severe reaction where the person may not be able to communicate.

Prognosis

Allergies cannot be cured. However, they can be treated with the help of medications to reduce the severity of symptoms.

Complications

The most severe and life-threatening form of an allergic reaction is anaphylaxis. It is a medical emergency and can be life-threatening if not treated on time and in some conditions may even lead to death. Other complications include asthma, eczema, recurrent ear and lung infections, polyps, sinusitis and migraine.