Allergy

An allergy is a reaction by your immune system to something that does not bother most other people. People who have allergies often are sensitive to more than one thing. Substances that often cause reactions are

• Pollen
• Dust mites
• Mold spores
• Pet dander
• Food
• Insect stings
• Medicines

Normally, your immune system fights germs. It is your body's defense system. In most allergic reactions, however, it is responding to a false alarm. Genes and the environment probably both play a role.

Allergies can cause a variety of symptoms such as a runny nose, sneezing, itching, rashes, swelling, or asthma. Allergies can range from minor to severe. Anaphylaxis is a severe reaction that can be life-threatening. Doctors use skin and blood tests to diagnose allergies. Treatments include medicines, allergy shots, and avoiding the substances that cause the reactions.

Allergy to pollen

Each spring, summer, and fall, trees, weeds, and grasses release tiny pollen grains into the air. Some of the pollen ends up in your nose and throat. This can trigger a type of allergy called hay fever.

Symptoms can include

• Sneezing, often with a runny or clogged nose
• Coughing and postnasal drip
• Itching eyes, nose and throat
• Red and watery eyes
• Dark circles under the eyes

Your health care provider may diagnose hay fever based on a physical exam and your symptoms. Sometimes skin or blood tests are used. Taking medicines and using nasal sprays can relieve symptoms. You can also rinse out your nose, but be sure to use distilled or sterilized water with saline. Allergy shots can help make you less sensitive to pollen and provide long-term relief.

Food Allergy

Food allergy is an abnormal response to a food triggered by your body's immune system.

In adults, the foods that most often trigger allergic reactions include fish, shellfish, peanuts, and tree nuts, such as walnuts. Problem foods for children can include eggs, milk, peanuts, tree nuts, soy, and wheat.

Symptoms of food allergy include

• Itching or swelling in your mouth
• Vomiting, diarrhea, or abdominal cramps and pain
• Hives or eczema
• Tightening of the throat and trouble breathing
• Drop in blood pressure

Your health care provider may use a detailed history, elimination diet, and skin and blood tests to diagnose a food allergy.

When you have food allergies, you must be prepared to treat an accidental exposure. Wear a medical alert bracelet or necklace, and carry an auto-injector device containing epinephrine (adrenaline).

You can only prevent the symptoms of food allergy by avoiding the food. After you and your health care provider have identified the foods to which you are sensitive, you must remove them from your diet.

Allergy to Medicines

Most of the time, medicines make our lives better. They reduce aches and pains, fight infections, and control problems such as high blood pressure or diabetes. But medicines can also cause unwanted reactions.

One problem is interactions, which may occur between

• Two drugs, such as aspirin and blood thinners
• Drugs and food, such as statins and grapefruit
• Drugs and supplements, such as gingko and blood thinners
• Drugs and diseases, such as aspirin and peptic ulcers

Interactions can change the actions of one or both drugs. The drugs might not work, or you could get side effects.

Side effects are unwanted effects caused by the drugs. Most are mild, such as a stomach aches or drowsiness, and go away after you stop taking the drug. Others can be more serious.

Drug allergies are another type of reaction. They can be mild or life-threatening. Skin reactions, such as hives and rashes, are the most common type.

When you start a new prescription or over-the-counter medication, make sure you understand how to take it correctly. Know which other medications and foods you need to avoid. Ask your health care provider or pharmacist if you have questions.

Source: http://www.nlm.nih.gov/medlineplus/allergy.html