Symptoms
Allergy symptoms vary, but may include:
- Breathing problems
- Burning, tearing, or itchy eyes
- Conjunctivitis (red, swollen eyes)
- Coughing
- Diarrhea
- Headache
- Hives
- Itching of the nose, mouth, throat, skin, or any other area
- Runny nose
- Skin rashes
- Stomach cramps
- Vomiting
- Wheezing
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Causes
Allergies are relatively common. Both genetics and environmental factors play a role.
Allergy is caused by an oversensitive immune system, which leads to a misdirected immune response. The immune system normally protects the body against harmful substances, such as bacteria and viruses. It reacts to substances ( allergens ) that are generally harmless and in most people do not cause a problem.
But in a person with allergies, the immune response is oversensitive. When it recognizes an allergen, it releases chemicals, such as histamines. This causes itching , swelling , mucus production, muscle spasms , hives , rashes , and other symptoms, which vary from person to person.
What part of the body is contacted by the allergen plays a role in the symptoms you develop. For example, allergens that are breathed in often cause a stuffy nose, itchy nose and throat, mucus ...
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Treatment
The best way to reduce symptoms is to try and avoid what causes your allergies in the first place. This is especially important for food and drug allergies.
The most appropriate medication depends on the type and severity of symptoms. Specific illnesses that are caused by allergies (such as asthma, hay fever, and eczema) may require other treatments. Medications that can be used to treat allergies include:
ANTIHISTAMINES
- Short-acting antihistamines are generally available over-the-counter. They help relieve mild to moderate symptoms but may cause drowsiness. In addition, the short-acting antihistamine diphenhydramine (Benadryl) can affect a child's learning abilities. Loratadine (Claritin) does not tend to cause drowsiness or affect learning in children.
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Possible Complications
- Anaphylaxis (life-threatening allergic reaction)
- Breathing problems and discomfort during the allergic reaction
- Drowsiness and other side effects of medicines
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Outlook (Prognosis)
Most allergies can be easily treated with medication.
Some children may outgrow an allergy. This is particularly true of food allergies. However, as a general rule, once a substance has triggered an allergic reaction, it continues to affect the person.
Allergy shots are most effective when used to treat those with hay fever symptoms and severe insect sting allergies. They do not work well for food allergies. Allergy shots may require years of treatment, but they work in about two-thirds of cases. However, they may cause uncomfortable side effects (such as hives and rash) and dangerous outcomes (such as anaphylaxis).
Prevention
Children who have been breastfed are less likely to have allergies. In addition, a mother who avoids cow's milk, eggs, nuts, and peanuts while breastfeeding can prevent allergy-related conditions, including eczema, in some children.
If there is a family history of eczema and allergies it is wise to discuss the implications for infant feeding with your child's doctor. The timing of introduction of solid foods in general, as well as of several specific foods, can help prevent some allergies.
There is also evidence that infants exposed to certain airborne allergens (such as dust mites and cat dander) may be less likely to develop related allergies. This is called the "hygiene hypothesis" and sprang from observations that infants on farms tend to have fewer ...
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Exams and Tests
The health care provider will perform a physical exam and ask questions such as when the allergy occurs.
Allergy testing may be needed to determine if the symptoms are an actual allergy or caused by other problems. For example, eating contaminated food ( food poisoning ) may cause symptoms similar to food allergies. Some medications (such as aspirin and ampicillin) can produce non-allergic reactions, including rashes.
Skin testing is the most common method of allergy testing. One type of skin testing is the scratch test. It involves placing a small amount of the suspected allergy-causing substances on the skin, and then slightly scratching the area so the substance moves under the skin. The skin is closely watched for signs of a reaction, which include swelling and redness. Skin ...
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References
Christodoulopoulos P, Tulic MK, Kontolemos M, Hamid Q. Immunopathology of Allergic Airway Inflammation.In: Middleton's Allergy: Principles and Practice. 6th ed. St. Louis, Mo: Mosby; 2003; 501-511.
Goldman L, Ausiello D. Cecil Textbook of Medicine , 22nd ed. Philadelphia, Pa: WB Saunders; 2004:1590-1591.
