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Allergies: Introduction

Allergies are caused by an over-reaction of the immune system to a particular substance or allergen. Allergies, also called allergic reactions, are common, and there are a variety of types of allergies. They include food allergies, respiratory allergies and skin allergies, which can result in such conditions as eczema and contact dermatitis.

The immune system is made up of special cells that circulate throughout the body to defend the body against foreign substances, such as viruses and bacteria. For people with allergies, the immune system is overzealous and reacts when they inhale, swallow or touch normally harmless substances, such as pollen or dust. This results in the release of the chemical histamine, which causes the swelling, inflammation, and itching of tissues that is characteristic of allergies.

Almost any substance can cause allergies in a person who is sensitive to that particular substance. People with allergies are often allergic to more than one substance. Common allergies include those to dust, pollen, mold spores, animal dander, bee stings, and cockroach or dust mite droppings. Some people may also have allergies to certain plants, some medications, such aspirin or penicillin, certain foods, such as eggs or milk, or chemicals and other substances, such as latex.

When a person has allergies, exposure to an allergen can cause a wide variety of symptoms, depending on the specific allergies, the type of exposure and the severity of the allergies. Symptoms can affect the respiratory system, the skin and/or the gastrointestinal system. A very severe allergic reaction is called an anaphylactic reaction, which can be fatal. For more information on symptoms and complications, refer to symptoms of allergies.

Making a diagnosis of allergies includes performing a complete evaluation that includes a medical history, including symptoms, and physical examination.

Diagnostic testing may include skin patch testing. In a patch test, small amounts of common allergens are applied methodically to the skin to determine what substances are triggering an allergic response. A blood test called a radioallergosorbent test (RAST) may also be done to help identify the substances that are causing certain allergies. For suspected food allergies, a patient may also be asked to keep a log to record the types of foods that trigger an allergic reaction.

It is very possible that a diagnosis of allergies can be missed or delayed because symptoms can be similar to other conditions. For more information on misdiagnosis, refer to misdiagnosis of allergies.

Patient compliance with a good treatment plan can control symptoms of allergies to a degree that allows a person to live a normal active life. Treatment may include a combination of lifestyle changes, medications, and other measures. For more information on treatment, refer to treatment of allergies. ...more »

Allergies: A respiratory allergy or allergic reaction is an over-reaction by the immune system to a particular substance, or allergen. The immune system is made up of special cells that circulate throughout the body to defend the body against foreign substances, such as viruses and bacteria. This is a normal protective response, but for people with allergies, the immune system gets overzealous in its job and reacts when they inhale, swallow or touch harmless substances, such as pollen or dust. Almost any substance can become an allergen and cause an allergic reaction in a person who is sensitive to that particular substance. People with allergies are often allergic to more than one substance.

A severe reaction, also called an anaphylactic reaction, can become life threatening and requires immediate medical intervention. Respiratory allergies can also become serious for people with asthma. Allergens can trigger an asthma attack which results in constriction of the airways in the lungs, inflammation, and build up and blockage by mucus. This results in wheezing, shortness of breath, coughing, which can become severe and life threatening. ...more »

Allergies: Symptoms

People who have allergies can experience a wide variety of symptoms that can affect the respiratory system, skin, gastrointestinal system, and in severe cases, the cardiovascular system. Symptoms can occur alone or in combination with other symptoms.

Respiratory symptoms include sneezing, runny nose, itchy, watery eyes, nasal congestion, sinus pressure, and headache. Hay fever ...more symptoms »

Allergies: Treatments

The most effective treatment plan for allergies uses a multifaceted approach. Treatment plans are also individualized to best address the specific cause and severity of the allergies, and the patient's age and medical history. In general, allergies are highly treatable, although they are generally not curable. On occasion, some young children might "grow out" ...more treatments »

Allergies: Misdiagnosis

A diagnosis of allergies may be overlooked or delayed because symptoms may be mild in some people and/or may not occur very often. In addition, some symptoms, such as sneezing, runny nose, vomiting or diarrhea can mimic symptoms of other conditions, such as a cold, food poisoning, gastroenteritis, influenza or indigestion.

Allergies and the allergens that ...more misdiagnosis »

Symptoms of Allergies

Treatments for Allergies

  • Antihistamine drugs
  • Hospitalization - for an asthma attack
  • Emergency treatment - for a severe asthma attack or anaphylactic shock
  • Vitamin B5 - possibly used for related vitamin B5 deficiency
  • Treatment of allergy is dependant upon the type of allergic symptom, the body system affected, and the severity of the reaction. Treatments for allergies include:
  • more treatments...»

Home Diagnostic Testing

Home medical testing related to Allergies:

Wrongly Diagnosed with Allergies?

Allergies: Related Patient Stories

Allergies: Deaths

Read more about Deaths and Allergies.

Alternative Treatments for Allergies

Alternative treatments or home remedies that have been listed in various sources as possibly beneficial for Allergies may include:

Types of Allergies

Curable Types of Allergies

Possibly curable types of Allergies include:

Rare Types of Allergies:

Rare types of Allergies include:

Allergies: Complications

Review possible medical complications related to Allergies:

Causes of Allergies

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More information about causes of Allergies:

Disease Topics Related To Allergies

Research the causes of these diseases that are similar to, or related to, Allergies:

Allergies: Undiagnosed Conditions

Commonly undiagnosed diseases in related medical categories:

Misdiagnosis and Allergies

Mild worm infections undiagnosed in children: Human worm infestations, esp. threadworm, can be overlooked in some cases, because it may cause more »

Mesenteric adenitis misdiagnosed as appendicitis in children: Because appendicitis is one of the more feared conditions for a child with abdominal pain, it can be over-diagnosed (it can, of course, also more »

Blood pressure cuffs misdiagnose hypertension in children: One known misdiagnosis issue with hyperension, arises in relation to the simple equipment used to test blood pressure. The "cuff" around the arm to measure blood more »

Psoriasis often undiagnosed cause of skin symptoms in children: Children who suffer from the skin disorder called psoriasis can often go undiagnosed. The main problem is that psoriasis is rare more »

Children with migraine often misdiagnosed: A migraine often fails to be correctly diagnosed in pediatric patients. These patients are not the typical more »

Chronic lung diseases hard to diagnose: Some of the chronic lung diseases are difficult to diagnose. Even the well-knowns conditions such as asthma or lung cancer often fail to more »

Allergies: Research Doctors & Specialists

Research related physicians and medical specialists:

Other doctor, physician and specialist research services:

Hospitals & Clinics: Allergies

Research quality ratings and patient safety measures for medical facilities in specialties related to Allergies:

Choosing the Best Hospital: More general information, not necessarily in relation to Allergies, on hospital performance and surgical care quality:

Allergies: Rare Types

Rare types of diseases and disorders in related medical categories:

Latest Treatments for Allergies

Allergies: Animations

Research about Allergies

Visit our research pages for current research about Allergies treatments.

Statistics for Allergies

Allergies: Broader Related Topics

Allergies Message Boards

Related forums and medical stories:

User Interactive Forums

Read about other experiences, ask a question about Allergies, or answer someone else's question, on our message boards:

Article Excerpts about Allergies

Something in the Air Airborne Allergens: NIAID (Excerpt)

An allergy is a specific immunologic reaction to a normally harmless substance, one that does not bother most people. People who have allergies often are sensitive to more than one substance. Types of allergens that cause allergic reactions include pollens, dust particles, mold spores, food, latex rubber, insect venom, or medicines. (Source: excerpt from Something in the Air Airborne Allergens: NIAID)

Allergies: NWHIC (Excerpt)

Allergies involve an immune response in the body to things such as plant pollen, other grasses and weeds, certain foods, rubber latex, insect bites, or certain drugs. Estimates suggest that allergies affect more than 50 million people in the United States. Nearly 10% of American women have pollen allergies. Allergic drug reactions, commonly caused by antibiotics such as penicillin, occur in 2%-3% of hospitalized patients. Severe allergic reaction to insect stings occurs in up to 5% of the population. Although most people have experienced a reaction to something they have eaten, only 1% of the adult population suffers from true immune reactions to food. (Source: excerpt from Allergies: NWHIC)


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