Allergy

Allergies occur when your immune system reacts to a foreign substance — such as pollen, bee venom or pet dander — or a food that doesn’t cause a reaction in most people.

An allergen is a substance that triggers an allergic reaction. Allergens can be drugs, environmental factors, or food products.

The most common allergens include:

• Dust
• Cockroaches
• Pet dander, as well as pet fur, pee, and spit
• Mold
• Pollen
• Some foods, especially milk, eggs, wheat, soy, peanuts, tree nuts, and shellfish
• Bug venom, especially from bees, yellow jackets, wasps, hornets, and fire ants
• Latex
• Some medications, particularly antibiotics including penicillin and nonsteroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen and naproxen

What is the immune system?

The purpose of the immune system is to defend itself and keep microorganisms, such as certain bacteria, viruses, and fungi, out of the body, and to destroy any infectious microorganisms that do invade the body. The immune system is made up of a complex and vital network of cells and organs that protect the body from infection.

The organs involved with the immune system are called the lymphoid organs. They affect growth, development, and the release of lymphocytes (a type of white blood cell). The blood vessels and lymphatic vessels are important parts of the lymphoid organs. They carry the lymphocytes to and from different areas in the body. Each lymphoid organ plays a role in the production and activation of lymphocytes.

Lymphoid organs include:

• Adenoids (two glands located at the back of the nasal passages)
• Appendix (a small tube that is connected to the large intestine)
• Blood vessels (the arteries, veins, and capillaries through which blood flows)
• Bone marrow (the soft, fatty tissue found in bone cavities)
• Lymph nodes (small organs shaped like beans, which are located throughout the body and connect via the lymphatic vessels)
• Lymphatic vessels (a network of channels throughout the body that carries lymphocytes to the lymphoid organs and bloodstream)
• Peyer’s patches (lymphoid tissue in the small intestine)
• Spleen (a fist-sized organ located in the abdominal cavity)
• Thymus (two lobes that join in front of the trachea behind the breast bone)
• Tonsils (two oval masses in the back of the throat)

Your immune system produces substances known as antibodies. When you have allergies, your immune system makes antibodies that identify a particular allergen as harmful, even though it isn’t. When you come into contact with the allergen, your immune system’s reaction can inflame your skin, sinuses, airways or digestive system.

Symptoms: 

Allergy symptoms, which depend on the substance involved, can affect your airways, sinuses and nasal passages, skin, and digestive system. Allergic reactions can range from mild to severe. 

A runny or stuffy nose can also be a symptom of allergies. Allergic rhinitis, known as hay fever, is a term used to describe allergic reactions in the nose. Symptoms of hay fever can include sneezing, congestion and runny nose, as well as itching in your nose, eyes and/or the roof of your mouth.

Other allergy-related conditions can cause a runny or stuffy nose, as well as sneezing. These include:

Sinus infection. There are two major forms of sinus infections (also called sinusitis): acute and chronic. Both acute and chronic sinus infections can be viral or bacterial. Some long-standing infections are fungal.

Decongestant nasal spray overuse. Over-the-counter decongestant nasal sprays are commonly used to relieve nasal congestion from colds or allergies. But if you use them regularly for as little as three days, a rebound nasal congestion can occur. If you continue to use the spray, the rebound effect gets worse and worse, leading to almost chronic nasal blockage. Many times, people with this condition don’t realize that the spray is causing the problem.

Nonallergic rhinitis. These are ailments that mimic some of the symptoms of hay fever, such as nasal congestion and postnasal drip, but are not caused by allergies. Different than nasal allergies, these nonallergic nasal problems usually appear in adulthood, don’t usually make your nose and eyes itch, don’t include sneezing and often occur year-round.

Although asthma and chronic obstructive pulmonary disease are most often associated with wheezing, an allergic reaction is another common cause of these symptoms.

Sometimes children experience wheezing, but it is not always a sign of asthma. A lung infection can create wheezing in children younger than 5. And wheezing and shortness of breath can sometimes be symptoms of a cold in children with a family history of allergies.

Eczema, contact dermatitis and hives are three common kinds of skin rashes that may be related to allergies.

Eczema

Eczema (also called atopic dermatitis) frequently appears as dry, red, cracking and itchy skin. If you have eczema, you may also experience small bumps that ooze a clear or yellowish fluid.

Contact Dermatitis

Contact dermatitis is an allergic skin reaction to an irritant or allergen. The reaction can appear as a rash, blisters, burning or itching.

Hives

Hives (also called urticaria) are red, itchy welts or bumps that don’t usually last long. Hives lasting less than six weeks (acute urticaria) are usually caused by an allergic reaction or a viral infection. They may appear on different parts of the body but usually last 24 hours or less.

Nausea and vomiting are rarely, if ever, symptoms of a seasonal allergy. Typical seasonal allergy symptoms include sneezing, runny nose, itchy eyes and maybe a rash.

If you encounter something you’re allergic to, your immune system considers the substance dangerous and releases a chemical called histamine to counteract it. Histamine can cause a variety of symptoms, including rash, headache, sneezing, runny nose and swelling — and in the case of food allergies, nausea, vomiting and diarrhea. If the allergen is something you breathe in, your reaction will probably affect your eyes, nose and lungs. If you eat the allergen, you’re more likely to have symptoms in your mouth, stomach and intestines.

In some severe cases, allergies can trigger a life-threatening reaction known as anaphylaxis.

Anaphylaxis is a severe, life-threatening allergic reaction. It can happen seconds or minutes after you’ve been exposed to something you’re allergic to. Peanuts or bee stings are examples. In anaphylaxis, the immune system releases a flood of chemicals that can cause the body to go into shock. Blood pressure drops suddenly, and the airways narrow, blocking your breathing. The pulse may be fast and weak, and you may have a skin rash. You may also get nauseous and vomit. Anaphylaxis needs to be treated right away with an injection of epinephrine. If it isn’t treated right away, it can be deadly.

Anaphylaxis is a severe, potentially life-threatening allergic reaction. It can occur within seconds or minutes of exposure to something you’re allergic to, such as peanuts or bee stings.

Anaphylaxis causes the immune system to release a flood of chemicals that can cause you to go into shock — blood pressure drops suddenly and the airways narrow, blocking breathing. Signs and symptoms include a rapid, weak pulse; a skin rash; and nausea and vomiting. Common triggers include certain foods, some medications, insect venom and latex.

Anaphylaxis requires an injection of epinephrine and a follow-up trip to an emergency room. If you don’t have epinephrine, you need to go to an emergency room immediately. If anaphylaxis isn’t treated right away, it can be fatal.

Prevention

The best way to prevent anaphylaxis is to stay away from substances that cause this severe reaction. Also:

Wear a medical alert necklace or bracelet to indicate you have an allergy to specific drugs or other substances.

Keep an emergency kit with prescribed medications available at all times. Your provider can advise you on the contents. If you have an epinephrine autoinjector, check the expiration date and be sure to refill the prescription before it expires.

Be sure to alert all your providers to medication reactions you’ve had.

If you’re allergic to stinging insects, use caution around them. Wear long-sleeved shirts and pants; don’t walk barefoot on grass; don’t wear bright colors; don’t wear perfumes, colognes or scented lotions; and don’t drink from open soda cans outdoors. Stay calm when near a stinging insect. Move away slowly and don’t slap at the insect.

If you have food allergies, carefully read the labels of all the foods you buy and eat. Manufacturing processes can change, so it’s important to periodically recheck the labels of foods you commonly eat.

Types of allergies: 

All allergens are not the same, and a person’s reaction may vary in degree of seriousness. When consulting an allergist you will be tested for different allergens, and the best treatment plan will be determined by the allergist.  

The most common allergens responsible for allergic reactions are:

Seasonal Allergy

If you find yourself sneezing or coughing during certain times of the year, you may suffer from seasonal allergies. Across the United States, trees bloom during the spring. Tree pollen season lasts from the end of February until early June, followed by grass season in the summer. In the fall, many people suffer with ragweed and weed allergies.

Drugs and Medications

Reactions to medications are relatively common. However, there are varying degrees to these reactions. One person may develop a rash and/or swelling while another may develop difficulty breathing. Typically, 5-10 percent of drug reactions are due to an allergic reaction to the medication. The drugs that cause the most common reactions are: antibiotics (penicillin), aspirin/nonsteroidal anti-inflammatory medications, chemotherapy, monoclonal antibody therapy, and anticonvulsants. The risk of developing a drug allergy increases when you take the medication frequently, if the medication physically touches your skin, or is given through injection.  

Foods

Most food allergies develop in childhood, though food allergies can also develop as an adult. The foods responsible for most food allergies in adults are: fish, peanuts, shellfish, tree nuts. Food allergies are not the same as food intolerances. In food allergies, the immune system overreacts to a protein found in food. Allergic symptoms can appear immediately after ingesting the food. Allergic reactions to food can be life-threatening. People with food allergies must be extra careful to avoid the food to which they are allergic to.

Latex

Latex is less common than it was in the past. Latex can be found in rubber gloves, condoms, balloons, toys, and rubber bands. It is a substance produced by rubber trees and blended with chemicals during the manufacturing process that gives it elasticity.

Nearly 50 percent of people with latex allergy also suffer from another allergy. Some patients with a latex allergy also have allergies to fruits and vegetables like bananas, avocado, tomatoes, or chestnuts can cause reactions in people sensitive to latex. Latex allergy can range from mild to severe. Allergic reactions can worsen with continued exposure. Latex allergies can be diagnosed by an allergist.

Mold

There are hundreds of mold types, but not all of them cause allergy symptoms. Molds are the tiny fungi spores that can be found present in the air. Mold flourishes in damp environments and can be found in houses or other buildings and outside. Everyone comes in contact with the spores that float through the air. But not everyone has a reaction to mold. Allergic reactions to molds can cause coughing, itchy eyes, congestion, and other allergy symptoms that make you feel awful. Mold allergies have been linked to asthma worsening, and consistent exposures to them can restrict airways and cause difficulty in breathing. Alternaria, Aspergillus, Cladosporium, and Penicillium are the most common allergy-causing molds.

Pet Dander

Pet allergies are common. Cat allergies are more common than dogs. The source of the allergen from cats and dogs are their saliva, urine and dander, not their fur.

Pet dander is the tiny flakes of skin from pets that shed. Typically associated with cats and dogs, animal dander can come from any animal with fur. An allergic reaction to pet dander includes sneezing, runny nose, wheezing, difficulty breathing, and in worse cases this can trigger asthma symptoms. It’s best to avoid exposure to the animal that triggers your allergies as much as possible. People with a pet dander allergy who come in direct contact can develop a skin reaction called dermatitis.

Venom (Stinging Insect)

Most people develop swelling, redness, and itching when they’ve been stung by an insect. A person allergic to venom experiences more severe symptoms since their immune system over reacts to the venom. If you are stung by an insect, your body produces antibodies called immunoglobulin E (IgE). If you are stung again by the same kind of insect, the IgE reacts to the venom and triggers an allergic reaction. A very small number of people have a life-threatening reaction to venom. In severe cases, a person can develop anaphylaxis <Link to: Anaphylaxis page> which requires immediate attention. Anaphylaxis is a severe, life-threatening allergic reaction. If you develop anaphylaxis symptoms after an insect bite, seek immediate medical attention.

How can Allergies be Prevented?

Identification and avoidance of allergy triggers are the most important step in preventing allergic reactions and reducing symptoms.

Quitting smoking

• Food allergies can be avoided by carefully checking the label for the list of ingredients. Care should be taken when eating food in a restaurant. 
• Dust mites are insects found in household dust. House dust mites are a major allergy trigger. Dust mites can be controlled by using the following strategies:
• Avoiding the use of carpets and using wood or hard vinyl floorings.
• Regularly washing and vacuuming cushions, soft toys, curtains and sofas.
• Using a HEPA (high efficiency particulate air) filter.
• Regularly wiping surfaces with a damp, clean cloth.
• Molds spores can be avoided by keeping the rooms dry and ventilated.
• If the pets cannot be avoided, it is advisable to keep them clean and groomed. Limiting them to a particular area of the house and avoiding their entry in bedrooms may also help.

Treatment of Allergies: 

Medications

Medications can help relieve allergic symptoms by reducing the body’s immune system reaction. Physician may suggest over-the-counter or prescription medication to treat allergies.

• Antihistamines – Antihistamines are the main category of medicines for allergies. They can be used when the symptoms of an allergy develop. They can also be used to prevent allergic reactions.
• Decongestants – Decongestants can be used to provide relief from a blocked nose caused by an allergic reaction; however, the long-term use of decongestants is associated with deterioration of symptoms and is hence not advisable.
• Lotions and creams to treat skin reactions – Certain allergies can lead to skin reaction such as rashes and itchiness. Itchiness caused by an allergic reaction can be treated with creams and lotions. They keep the skin moist and protect it the skin from allergens. Calamine lotion can also be used to reduce itchiness.
• Steroids – Medication containing steroids can be used to reduce inflammation caused by an allergic reaction. Steroids are available as creams, tablets, nasal sprays and eye drops.

Immunotherapy

Severe cases of allergies that do not respond to conventional treatment can be treated with allergen immunotherapy. Allergen immunotherapy involves the administration of allergen extracts into the body via injections. They are usually administered over a period of a few years. Immunotherapy may also be administered as drops or sublingual tablets.