Vaccine Controversies
An allergy is an immune response or reaction to substances that are usually not harmful.
Allergies are pretty common. Both genes and environment play a role.
The immune system normally protects the body against harmful substances, such as bacteria and viruses. It also reacts to foreign substances called allergens, which 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, the immune system launches a response. Chemicals such as histamines are released. These chemicals cause allergy symptoms.
Common Allergies Include:
- Drugs
- Dust
- Food
- Insect venom
- Mold
- Pet and other animal dander
- Pollen
Some people have allergy like reactions to hot or cold temperatures, sunlight, or other environmental triggers. Sometimes, friction (rubbing or roughly stroking the skin) will cause symptoms.
An allergy is not usually passed down through families (inherited). However, if both your parents have allergies, you are also likely to have allergies. The chance is greater if your mother has allergies.
Allergies may make certain medical conditions, such as sinus problems, eczema, and asthma, worse.
Symptoms:
The part of the body the allergen touches affects what symptoms you develop. For example:
- Allergens that you breathe in often cause a stuffy nose, itchy nose and throat, mucus production, cough, and wheezing.
- Allergens that touch the eyes may cause itchy, watery, red, swollen eyes.
- Eating something you are allergic to can cause nausea, vomiting, abdominal pain, cramping, diarrhea, or a severe, life-threatening reaction.
- Allergens that touch the skin can cause a skin rash, hives, itching, blisters, or skin peeling.
- Drug allergies usually involve the whole body and can lead to a variety of symptoms.
Exams and Tests:
Skin testing is the most common method of allergy testing. One type of skin testing is the prick test. It involves placing a small amount of the suspected allergy-causing substances on the skin, and then slightly pricking 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 testing may be an option for some young children and infants.
Other types of skin tests include patch testing and intradermal testing.
Blood tests can measure the levels of allergy-related substances, especially one called immunoglobulin E (IgE).
A Complete Blood Count (CBC) called the eosinophil white blood cell count may also help diagnose allergies.
In some cases, the doctor may tell you to avoid certain items to see if you get better, or to use suspected items to see if you feel worse. This is called “use or elimination testing.” This is often used to check for food or medication allergies.
The doctor may also check your reaction to physical triggers by applying heat, cold, or other stimulation to your body and watching for an allergic response.
Sometimes, a suspected allergen is dissolved and dropped into the lower eyelid to check for an allergic reaction. This should only be done by a health care provider.
Skin testing is the most common method of allergy testing. One type of skin testing is the prick test. It involves placing a small amount of the suspected allergy-causing substances on the skin, and then slightly pricking 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 testing may be an option for some young children and infants.
Other types of skin tests include patch testing and intradermal testing.
Blood tests can measure the levels of allergy-related substances, especially one called immunoglobulin E (IgE).
A Complete Blood Count (CBC) called the eosinophil white blood cell count may also help diagnose allergies.
In some cases, the doctor may tell you to avoid certain items to see if you get better, or to use suspected items to see if you feel worse. This is called “use or elimination testing.” This is often used to check for food or medication allergies.
The doctor may also check your reaction to physical triggers by applying heat, cold, or other stimulation to your body and watching for an allergic response.
Sometimes, a suspected allergen is dissolved and dropped into the lower eyelid to check for an allergic reaction. This should only be done by a health care provider.
Treatment:
Common Allergy Medications Include:
Antihistamines
- Capsules and pills
- Eye drops
- Injection
- Liquid
- Nasal spray
Corticosteroids
- Cream and ointments for the skin
- Eye drops
- Lung Inhaler
- Nasal spray
Decongestants
Immunotherapy - Allergy Shots
Prognosis:
Most allergies can be easily treated with medication.
Some children may outgrow an allergy, especially food allergies. However, once a substance has triggered an allergic reaction, it usually continues to affect the person.
Allergy shots are most effective when used to treat people with hay fever symptoms and severe insect sting allergies. They are not used to treat food allergies because of the danger of a severe reaction.
Allergy shots may need years of treatment, but they work in most cases. However, they may cause uncomfortable side effects (such as hives and rash) and dangerous outcomes (such as anaphylaxis).
Possible Complications:
- Anaphylaxis (life-threatening allergic reaction)
- Breathing problems during the allergic reaction
-
Drowsiness and other side effects of medicines
Contact a Medical Professional If:
- Severe allergy symptoms occur
- Treatment for allergies is no longer working
If you are having difficulty breathing from a severe allergic reaction, go to the Emergency Room immediately.
Prevention:
Breastfeeding can help prevent or decrease allergies when you feed babies this way only for 4 to 6 months. However, changing a mother’s diet during pregnancy or while breastfeeding does not seem to help prevent allergies.
For most children, changing the diet or using special formulas does not seem to prevent allergies. If a parent, brother, sister, or other family member has a history of eczema and allergies, discuss feeding with your child’s doctor.
There is also evidence that being exposed to certain allergens (such as dust mites and cat dander) in the first year of life may prevent some allergies. This is called the “hygiene hypothesis.” It came from the observation that infants on farms tend to have fewer allergies than those who grow up in more sterile environments. However, older children do not seem to benefit.
Once allergies have developed, treating the allergies and carefully avoiding allergy triggers can prevent reactions in the future.
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Bielory L, Friedlaender MH. Allergic conjunctivitis. Immunol Allergy Clin North Am. 2008 Feb;28(1):43-58, vi.
Sicherer S, Sampson HA. Journal of Allergy and Clinical Immunology 2010 Feb 125 (2 suppl2) S116-25.
Borish L. Allergic rhinitis and sinusitis. In: Goldman L, Schafer AI, eds. Cecil Medicine. 24th ed. Philadelphia, Pa: Saunders Elsevier; 2011:chap 259.
