ALLERGIES

An allergy is an exaggerated immune response or reaction to substances that are generally not harmful.

Causes

Both genes and environmental factors play a role in allergies.

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, it releases chemicals such as histamines. which fight off the allergen. This causes allergy symptoms.

Common allergens include:

• Drugs
• Dust
• Food
• Insect bites
• Mold
• Pet dander
• Pollen

A specific allergy is not usually passed down through families (inherited). However, if both your parents have allergies, you are 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

Allergy symptoms may include:

• Breathing problems (coughing, shortness of breath)
• 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

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 find out whether the symptoms are an actual allergy or are caused by other problems. For example, eating contaminated food may cause symptoms similar to food allergies. Some medications (such as aspirin and ampicillin) can produce non-allergic reactions, including rashes. A runny nose or cough may actually be due to an infection.

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.

Treatment

Severe allergic reactions (anaphylaxis) need to be treated with a medicine called epinephrine, which can be life saving when given right away. The best way to reduce symptoms is to avoid what causes your allergies. This is especially important for food and drug allergies.

There are several types of medications to prevent and treat allergies. Which medicine your doctor recommends depends on the type and severity of your symptoms, your age, and overall health.

Illnesses that are caused by allergies (such as asthma, hay fever, and eczema) may need other treatments.

Medications that can be used to treat allergies include antihistamines, corticosteroids, decongestants.

Prevention

Breastfeeding children for at least 4 months or more may help prevent a cow's milk allergy and wheezing in early childhood.

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. When you introduce solid foods and what foods you give your baby can help prevent some allergies.

There is also evidence that infants who are exposed to certain allergens in the air (such as dust mites and cat dander) may be less likely to develop 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.