Food Allergy An Overview

Food allergies aren’t just bothersome — they can be costly, too. A study in the Journal of Allergy and Clinical Immunology found that food allergies — an exaggerated immune response that can be triggered by peanuts, milk, eggs, and other products — cost Americans $500 million a year, due to doctor visits, hospital care, and lost work days. Today, about one in 25 people in the United States have food allergies.

What Is a Food Allergy?

If you have a food allergy, your body’s immune system overreacts to certain food components known as food allergens. These allergens, which are usually proteins, are harmless to most people. But if your body’s immune system has been sensitized to the allergens, it may overreact and attack the proteins as if they were harmful bacteria.

Most people who have a food allergy are allergic to a protein found in one or more of the following foods:

  • Fish
  • Shellfish
  • Peanuts
  • Tree nuts
  • Soy
  • Wheat
  • Eggs
  • Cow’s milk

Food Allergy Symptoms

Symptoms of a food allergy may include:

  • Hives. These raised areas of the skin are red and itchy. Hives often appear in clusters.
  • Eczema. Also called atopic dermatitis, eczema appears as red areas on the skin that are itchy and scaly.
  • Asthma. A food allergy can trigger asthma, which is characterized by wheezing, coughing, and, possibly, trouble breathing.
  • Gastrointestinal symptoms. Vomiting, diarrhea, cramping, and gas are common symptoms of a food allergy.
  • Itching and swelling. A rash may appear around your mouth, and you may have itchiness and swelling of your mouth and throat.
  • Anaphylaxis. This life-threatening allergic reaction affects the whole body. Symptoms may include flushing, mouth tingling, a rash, dizziness, trouble breathing, excessive sneezing, anxiety, abdominal cramps, vomiting, diarrhea, low blood pressure, fainting, and shock. If you or someone around you is showing symptoms of anaphylaxis, contact emergency medical personnel immediately.

These symptoms usually appear within a few minutes to a couple of hours of eating the food you are allergic to. Rarely, an allergic reaction to a food can occur even when you do not consume the food, since some food allergens can become airborne (for example, when shellfish is steamed).

Diagnosing and Treating a Food Allergy

Anyone who has had symptoms of an allergic reaction to food should consult an allergist or immunologist, who can diagnose the condition and decide how to best treat it. Diagnosis of a food allergy will involve a complete medical history, physical exam, and allergy skin or blood tests to confirm the presence of the allergy.

The best treatment for a food allergy is to avoid the food that triggers the allergic reaction. However, this can be difficult if you don’t prepare your own meals. Here are some tips to help avoid problems when eating out and buying pre-made foods:

  • Talk to your hosts or wait staff about dish ingredients when dining away from home
  • Read all food labels and ask your doctor what ingredients you should watch out for
  • Avoid foods that don’t have labels

It is a good idea to always carry an injectable epinephrine or an antihistamine medication with you at all times, if recommended by your doctor. Also, consider wearing an identification bracelet that describes your allergy.

Some people, especially children, eventually “grow out” of their food allergy. But, there is currently no cure for food allergies. Researchers are working to find a cure and identify better ways to prevent and treat allergic reactions to food allergens.

All About Allergic Conjunctivitis

What causes the eye condition allergic conjunctivitis, and what are the treatment options?
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When your eyes are exposed to certain allergy-causing substances, inflammation of the conjunctiva (the thin membrane covering the eyeball and the inside of the eyelid) may occur resulting in allergic conjunctivitis. Millions of Americans suffer from allergic conjunctivitis, making it the most common allergy condition of the eye.

Conjunctivitis is often referred to as “pinkeye,” and the viral or bacterial forms of conjunctivitis are contagious. However, allergic conjunctivitis is not.
Types of Allergic Conjunctivitis

There are two forms of allergic conjunctivitis. The perennial form of allergic conjunctivitis is usually caused by animal hair or dander, feathers, and dust mites. According to Clifford Bassett, MD, clinical assistant professor of medicine at the State University of New York and clinical instructor at New York University School of Medicine in New York City, the more common form of allergic conjunctivitis is seasonal, which is triggered by mold spores and pollen from flowering trees, grass, and weeds.

“Seasonal allergic conjunctivitis is on the rise as a result of global warning,” says Dr. Bassett. “As greenhouse gases increase, there is an increase in pollen, especially ragweed.” Bassett also believes that “global warning is somehow making the pollen stickier,” which makes it more likely to adhere to the eyes.

Allergic conjunctivitis may also result from the presence of a foreign body in the eye, such as a contact lens or glass eye. This type of allergic conjunctivitis is known as giant papillary conjunctivitis, and typically occurs in a person who wears hard or rigid contact lenses.

Other substances that may cause an allergic reaction in the eyes include air pollutants, perfumes, cosmetics, chemicals, and smoke.
Allergic Conjunctivitis Symptoms

The most obvious symptoms of allergic conjunctivitis are redness and puffiness around the eyes, which Bassett says can “become a quality-of-life issue.” To cover these symptoms, Bassett says, “Women will often apply cosmetics, which only make their condition worse.” Other symptoms may include:

Watery eyes or increased amount of tears
Itching or burning eyes
Blurred vision
Increased sensitivity to light

Allergic Conjunctivitis Treatment Options

Bassett recommends visiting an allergist or an ophthalmologist at the first signs of allergic conjunctivitis to ensure the proper diagnosis before undergoing any treatment regimen. Discomfort can be relieved by applying cool compresses to the eyes. Bassett adds that allergy shots and prescription eye drops such as Patanol and Pataday (olopatadine hydrochloride) are very effective in relieving allergic conjunctivitis symptoms. Other treatment options include over-the-counter artificial tears and oral antihistamines.
Allergic Conjunctivitis Prevention

Since avoidance of the allergen is the best solution for allergic conjunctivitis, Bassett suggests the following steps for reducing or eliminating exposure to eye allergens:

Remain indoors during peak pollen counts
Wash hair and eyelids daily using a baby shampoo
Wear sunglasses when outdoors, especially on windy days, to block pollen from your eyes
Reduce dust mite exposure by keeping air ducts clean and using mattress covers or mite-proof bedding
Vacation in places near bodies of water, such as lakes and oceans, which have less pollen

While allergic conjunctivitis will not cause blindness, continuing discomfort is often the prognosis. Fortunately, anyone with a history of allergic conjunctivitis may prevent future outbreaks or lessen their severity by identifying the specific allergens causing their symptoms and being diligent to avoid exposure to them. See your doctor when you first notice symptoms and get relief.

Allergies from A to Z

Use this glossary to learn common terms, medications, and phrases related to allergies.
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Allergens: Substances that can trigger asthma attacks in people who have allergic asthma. Examples of allergens are dog or cat dander, dust mites or pollen.

Allergen skin test: test in which tiny amounts of suspected allergens are introduced into a patient’s skin with a pin-prick. In an allergic patient, the allergen will produce a swollen itchy patch surrounded by an area of redness.

Allergic asthma: A type of asthma in which an allergen triggers cellular reactions resulting in airway inflammation and asthma symptoms.

Allergic conjunctivitis: Also called “pink eye,” this is an inflammation of the conjunctiva, the tissue on the inside of the eyelid and keeps eyeball and eyelid moist. It is an extremely common condition that can be triggered by contact with irritating substances such as shampoo, dirt, smoke, pool chlorine, or various allergens.

Allergic reaction: The immune system’s response to an invading allergen in which the mast cells produce the protective antibody called immunoglobulin E (IgE). The IgE antibodies trigger the mast cells to release histamine and other chemicals which produce inflammation, swelling, mucous production, itching, rash, hives or other symptoms, depending on the type of allergy.

Allergic rhinitis: An allergic reaction that mainly involves swelling and inflammation of nasal passages and sinuses, including the symptoms of congestion, sneezing, and itchy, watery eyes.

Allergy: The body’s over-response to a foreign substance, producing an allergic reaction and the release of histamine or other chemicals.

Animal allergens: Allergens from animal sources, such as particles of proteins secreted by glands in the animal’s skin, then shed as dander, proteins from an animal’s saliva, feces, urine or feathers.

Anaphylaxis: A runaway allergic reaction that involves the whole body. Anaphylaxis can be so severe as to be life-threatening. It can cause extreme swelling in the lungs and airways that can make breathing or swallowing difficult, as well as severe abdominal pain, cramps, vomiting, diarrhea and mental confusion or dizziness.

Antihistamine: A medication that blocks histamine receptors to prevents symptoms of inflammation, congestion, sneezing and itchy eyes.

Anti-inflammatory medications: Medications that reduce the inflammation and swelling of airways that can cause asthma symptoms.

Asthma attacks: The sudden or gradual worsening of asthma symptoms, such as coughing, wheezing and breathlessness.

Asthma symptoms: Common examples are coughing, wheezing, chest tightness and difficulty breathing.

Atopy: The genetic tendency to produce IgE and allergic reactions causing asthma, allergic rhinitis and skin allergies asthma in response to ordinary substances.


Bee sting allergy: An allergy to the venom from a bee sting. People who are extremely allergic to bees can have a severe reaction to a bee sting, including anaphylaxis.

Bronchoconstriction: Tightening of the airway muscles that makes it hard for the asthma sufferer to breathe.

Bronchodilators: Asthma medicines that relax airway muscles to open them up and allow more air through.


Contact dermatitis: See skin contact allergy.


Drug allergy: An allergy to certain medications such as penicillin, sulfa drugs, anti-seizure medications, and aspirin. An allergic person taking the drug may get hives or exhibit other symptoms.

Dust mites: A common allergen, dust mites are tiny insects that live in households, in mattresses, pillows, carpets, curtains and upholstered furniture.


Eczema: A very common form of dermatitis in people who are atopic. Its symptoms are dry, scaly skin appearing on red, inflamed areas. Eczema also is extremely itchy and may cause burning sensation. People who suffer from asthma or allergic rhinitis often have eczema as well.

Elimination diet: A diet used to test for food allergies. To determine the allergy, particular foods are temporarily eliminated from the diet to narrow down and identify the source of the allergy symptoms.

Epinephrine: A chemical also called adrenaline that is used in a self-injectable syringe to treat severe allergic reactions, such as anaphylactic shock from a bee sting.


Food allergy: An allergic reaction caused by a harmless food protein that can provoke symptoms such as inflammation, congestion and hives.

Food intolerance: A response that occurs when something in a food irritates a person’s digestive system or when a person is unable to digest the food. The most common food intolerance is intolerance to lactose, the sugar component of milk. It is different than a food allergy because it does not involve an allergic reaction.


Hay fever: A seasonal allergic reaction caused by the pollen of grasses, weeds, trees and other plants.

Histamine: A naturally occurring substance released by the mast cells after being exposed to a threatening foreign substance in the body or, in an allergic person, an allergen. The histamine causes inflammation, swelling, congestion, mucus production and other symptoms of allergies.

Hives: These are itchy, raised rashes or patches on the skin that can appear suddenly when someone eats or comes in contact with a food or drug they are allergic to. Hives, also called urticaria, can appear anywhere on the body including the tongue and throat and can disappear in a few minutes or last for days.


IgE (abbreviation for immunoglobulin E): An antibody your body creates that, in some people, can sensitize the mast cell to allergens and cause the chemical reactions that may lead to an allergic reaction or asthma attack.

IgE blockers: A new class of asthma medication that prevents the attachment of the IgE antibodies to the mast cells and prevents the allergic response that can lead to an asthma attack.

Inflammation of the airways: Swelling of the lung airway tissue, resulting in a narrowed airway and difficulty breathing.

Immunotherapy: Also known as allergy desensitization or allergy shots; immunotherapy can increase the tolerance to an allergen by reducing the body’s sensitivity to it. However, it is not considered a cure for allergies. Immunotherapy usually is reserved for people who for people who suffer from allergies three months a year or more.


Latex: Latex is a sap from the rubber tree that is used to make rubber gloves, tubing, rubber bands, and other products. The powder residue that coats the latex product, which can become airborne, is what causes an allergic reaction in some people.


Mast cell: A type of white blood cell that releases chemicals such as histamine that trigger an allergic reaction.

Mold: A microscopic fungi that produce spores that can become airborne like pollen; it is a common trigger for allergies. Indoor mold is found in damp areas, such as basements, bathrooms or rooms that have leaks or have been flooded. Mold can also be found outdoors in grass, leaf piles, mulch, or around mushrooms.


Pollen: A powdery substance released by plants and trees as part of their reproductive cycle. Pollen grains are a very common allergen that can cause allergic reactions in many people.

Peak expiratory flow meter: A tool that measures how well the lungs work. A person blows (exhales) quickly and forcefully into the meter, which gives a reading that tells how open the airways are.

Pink eye: See allergic conjunctivitis.


Radioallergosorbent test (RAST): A blood test to determine the presence of certain antibodies in the blood. High levels of these antibodies point to particular allergies. The RAST blood test is not considered as accurate as the allergen skin test.


Sinusitis: A bacterial infection in the sinuses that causes inflammation. Sinusitis can occur acutely with the flare up of a bacterial infection, or it can be chronic with nasal membranes constantly inflamed. The condition affects many people with asthma. However, experts say at least half of all chronic sinusitis is not caused by allergies.

Skin contact allergy: Also called contact dermatitis, this is a kind of allergic reaction of the skin caused by direct contact with an allergen producing symptoms of inflammation. The inflammation can range from localized redness to open sores, depending on the particular allergen, the part of the body affected, and the individual’s sensitivity.

What Are the Different Types of Allergies?

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As many as 50 million Americans are allergic to something — whether pollen, peanuts, or pet dander. But not all allergies are the same. Here’s a rundown of the most common kinds of allergies.

Allergic rhinitis: swelling and inflammation of nasal passages, congestion, sneezing, and itchy, watery eyes caused by a variety of outdoor and indoor allergens.

Sinusitis: an infection of the sinuses sometimes related to or caused by allergic rhinitis or asthma. However, at least half of all chronic sinusitis is not caused by allergies.

Asthma: inflammation of the lungs and airways and constriction of the bronchial tubes triggered by many of the same allergens as allergic rhinitis, and resulting in wheezing, chest tightness, shortness of breath and coughing.

Food allergies: symptoms such as rash, vomiting and diarrhea, coughing, wheezing, facial swelling, hives, and others triggered by specific foods in some people. Food intolerances, such as lactose intolerance, are more common, but they are not considered allergies because they do not involve an allergic reaction.

Bee sting allergy (insect venom allergy): one of the most dangerous allergic reactions, especially for people who are severely allergic to bee stings. Causes swelling and inflammation around the site of the sting, and in severe cases, an anaphylactic reaction that involves the entire body. Symptoms include hives, swollen airways, wheezing, difficulty breathing and swallowing, increased pulse rate, and decreased blood pressure causing dizziness. People with bee and insect venom allergies must carry an epinephrine (adrenaline) self-injection kit (brand names include EpiPen and Twinject) with them at all times in case they are stung.

Latex allergy: a reaction to the manmade material Latex, most often in the powder residue that coats the latex in rubber gloves, which can become airborne. Symptoms may include asthma, itching and rash, hives, watery eyes, and anaphylaxis.

Drug allergies: reaction to certain medications, such as penicillin, sulfa drugs, anti-seizure medications, and aspirin that may cause hives or other symptoms when taken.

Skin contact allergy: also called contact dermatitis, an allergic reaction caused by direct contact with an allergen that produces inflammation ranging from localized redness to open sores. Common causes are acid and alkaline materials, including soaps and detergents; solvents, adhesives, and other industrial chemicals; poison ivy, oak or sumac; nickel and other metals used in jewelry; topical medications, including antibiotics and anesthetics; rubber; perfumes or cosmetics; fabrics such as wool and clothing made from such fabrics.

Eczema: a very common form of dermatitis and often a lifelong condition in people who are hypersensitive to a wide range of skin irritations. Symptoms include dry, scaly skin appearing on red, inflamed areas; extreme itchiness, and a burning sensation.

Allergic conjunctivitis: also called pink eye, an inflammation of the conjunctiva, the tissue on the inside of the eyelid that keeps the eyeball and eyelid moist. Can be triggered by contact with substances such as shampoo, cosmetics, dirt, smoke, pool chlorine, or various allergens.

Chemical sensitivity: not the same as an allergic reaction, the inability of the affected person to tolerate environmental chemicals, such as pesticides, solvent fumes and other air contaminants. Symptoms can include respiratory problems, nausea, headache, fatigue, cognitive dysfunction, heart arrhythmia, or seizures.