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Allergy Overview

What are allergies?

Allergies are problems of the immune system. Most allergic reactions happen when the immune system reacts to a “false alarm.” Normally, the human body defends itself against harmful things, such as viruses or bacteria. But sometimes the defenses violently attack mostly mild things, such as dust, mold, or pollen.

The immune system makes large amounts of the antibodies called immunoglobin E (IgE). This is a complex chemical weapon that attacks and kills the “enemy.” Each IgE antibody exactly targets a certain allergen or thing that causes the allergy. In this way, inflammatory chemicals, such as histamines, cytokines, and leukotrienes, are made and given off. This causes the person to feel some bad or even life-threatening symptoms.

What causes allergies?

Allergens are substances that can be breathed in, swallowed, or come in contact with the skin. Common allergic reactions, such as hay fever, certain types of asthma, and hives, are linked to an antibody made by the body. This antibody is called immunoglobulin E or IgE. A person can be allergic to one type of pollen, but not another. When a sensitive person is exposed to an allergen, the body starts making a large amount of matching IgE antibodies. When the person is exposed to the same allergen at a later point, he or she may have a reaction. Symptoms of an allergic reaction will differ based on the type and amount of allergen you have come in contact with. It also depends on how the body’s immune system reacts to that allergen.

The most common allergens are:

  • Pollen
  • Mold
  • Household dust, dust mites and their waste
  • Animal dander, urine, or oil from skin
  • Chemicals used for manufacturing
  • Food
  • Medicine
  • Feathers
  • Bug stings
  • Cockroaches and their waste
  • Latex

Who is at risk for allergies?

Allergies can affect anyone, no matter what age, gender, race, or socioeconomic status. Often, allergies are more common in children. But a first-time event can happen at any age, or come back after many years of remission.

There’s a tendency for allergies to happen in families. Although the exact family links that cause it aren’t yet understood. In sensitive people, things such as hormones, stress, smoke, perfume, or other environmental irritants, may also play a role. Often, the symptoms of allergies grow slowly over a period of time.

Allergy sufferers may become used to constant symptoms, such as sneezing, nasal congestion, or wheezing. They may not think that their symptoms are unusual. These symptoms can often be stopped or controlled with the help of an allergist. And the person can have a better quality of life.

What are the symptoms of allergies?

An allergic reaction can happen anywhere in the body. This includes the skin, eyes, lining of the stomach, nose, sinuses, throat, and lungs. These are the places where immune system cells are found to fight off germs that are in breathed in, swallowed, or come in contact with the skin. Allergic reactions can cause:

  • Stuffy nose, sneezing, itching, or runny nose, and itching in ears or roof of mouth
  • Red, itchy, watery eyes
  • Red, itchy, dry skin
  • Hives or itchy welts
  • Itchy rash
  • Asthma symptoms, such as shortness of breath, coughing, wheezing

How are allergies diagnosed?

To diagnose an allergy, your health care provider will give you an exam and take your medical health record. He or she may also do these tests.

  • Skin test. The skin test is a way of measuring the person’s level of IgE antibodies to certain allergens. Using diluted solutions of certain allergens, the health care provider either gives the person a shot with the solutions or puts them directly on the skin by making a scratch or small puncture. A small red area on the skin means that the person had a reaction.
  • Blood test. The blood test is used to measure the patient’s level of IgE antibodies to specific allergens. One common blood test is called radioallergosorbent test or RAST.

How are allergies treated?

Your health care provider will figure out the best treatment for you based on:

  • Your age
  • Your overall health and medical history
  • How sick you are
  • How well you can handle specific medications, procedures, or therapies
  • How long the condition is expected to last
  • Your opinion or preference

The symptoms of allergy sometimes look like other conditions or medical problems. Always see your health care provider for a diagnosis.

Allergy shots or immunotherapy and medicine are effective ways treat allergies.

Allergy shots. Allergy shots or immunotherapy is a type of treatment for allergic patients with rhinitis (hay fever), conjunctivitis, or asthma. It is also used for patients with a stinging bug allergy. A mixture of the many allergens to which the patient is allergic is made. It is injected into the patient’s arm on a weekly basis until a maximum dose is reached.

Most patients get better with allergy shots. It often takes from 12 to 18 months before clear reduction in allergy symptoms is noticed. In some patients, a reduction in symptoms is evident in as soon as six to eight months.

Allergy shots are only part of the treatment plan for allergic patients. Since it takes time for allergy shots to become effective, you will need to stay on the allergy meds, as prescribed by your heath care provider. It is also important to keep on getting rid of allergens (such as dust mites) from your surroundings.

Medicine. For people who suffer from allergies, there are many medicines that work well. Antihistamines are used to calm or stop the symptoms of allergic rhinitis (hay fever) and other allergies. Decongestants are used to treat stuffiness in the nose and other symptoms linked to colds and allergies. The use of medicines for asthma or breathing symptoms from allergies is tailored for each person based on the severity of the symptoms.

Talk with your health care provider for more information about allergy medicines.

What are the complications of allergies?

Anaphylactic shock or anaphylaxis can happen in extreme cases. Anaphylaxis is a serious, life-threatening reaction to certain allergens. Body tissues may swell, including tissues in the throat. Anaphylaxis can also cause a sudden drop in blood pressure. These are the most common symptoms of anaphylaxis. However, each person may feel symptoms differently.

Other symptoms may include:

  • Itching and hives over most of the body
  • Swelling of the throat and tongue
  • Difficulty breathing
  • Dizziness
  • Headache
  • Stomach cramps, nausea, or diarrhea
  • Shock
  • Loss of consciousness

Anaphylaxis can be caused by an allergic reaction to a drug, food, serum, bug venom, allergen extract, or chemical. Some people who are aware of their allergic reactions or allergens carry epinephrine. This is a drug that fires up the adrenal glands. It also increases the rate and force of the heartbeat.

Living with allergies

Avoidance is a very effective way to treat allergies. Ideas for avoiding allergens are:

  • Stay indoors when the pollen count is high and on windy days.
  • Dust-proof your home, particularly the bedroom.
    • When possible, get rid of carpeting, Venetian blinds, down-filled blankets or pillows, closets filled with clothes.
    • Wash bedding, curtains, and clothing often in hot water to get rid of dust mites.
    • Keep bedding in dust covers when possible.
  • Use air conditioning instead of opening the windows.
  • Put a dehumidifier in damp parts of the home, but remember to clean it often.
  • Wear face masks when working in the yard.
  • Go on vacation by the beach during the heaviest part of the pollen season.

Your health care provider will also have suggestions for avoiding the allergens that cause reactions.

Key points about allergies

  • Allergy is a reaction caused when the immune system mistakenly thinks a normally harmless substance is damaging to the body.
  • Allergens can be breathed, swallowed, or enter through the skin.
  • Allergies can affect anyone, no matter what age, gender, race, or socioeconomic status.
  • Allergies tend to happen in families. Although the exact family links that cause it aren’t yet understood.
  • Allergic reactions may cause:
    • Stuffy nose, sneezing, itching, or runny nose, and itching in ears or roof of mouth
    • Red, itchy, watery eyes
    • Red, itchy, dry skin
    • Hives or itchy welts
    • Itchy rash
    • Asthma problems, such as shortness of breath, coughing, and wheezing
  • To diagnose an allergy, your health care provider will give you an exam, take your medical health record, and do blood and skin tests.
  • The three most effective ways to treat allergies are avoidance, allergy shots, and medicine.
  • Anaphylaxis can happen in extreme cases.
  • Avoid allergens when possible.

Next steps

Tips to help you get the most from a visit to your health care provider:
  • Before your visit, write down questions you want answered.
  • Bring someone with you to help you ask questions and remember what your provider tells you.
  • At the visit, write down the names of new medicines, treatments, or tests, and any new instructions your provider gives you.
  • If you have a follow-up appointment, write down the date, time, and purpose for that visit.
  • Know how you can contact your provider if you have questions.
Online Medical Reviewer: Sather, Rita, RN
Online Medical Reviewer: Sohrabi, Farrokh, MD
Last Review Date: 1/31/2014
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