The immune system Overview of the Immune System The immune system is your body's defense system. It helps protect you from illness and infection. The immune system's job is to attack things that don’t belong in your body, including: Germs... read more is your body's defense system. It helps protect you from illness and infection. The immune system usually reacts to and attacks bacteria, viruses, and cancer cells. An allergy is when your body's immune system reacts to something harmless, such as food, plants, or medicine.
What is an allergic reaction?
An allergic reaction is what happens when you touch, eat, or breathe something you're allergic to. Allergic reactions can be mild or severe.
Mild reactions are unpleasant and annoying
Severe reactions can be life-threatening
What causes an allergic reaction?
Doctors aren't sure why some people who are exposed to a substance become allergic to it and others don't.
Allergies seem to run in families
What you were exposed to and ate when you were a child may affect whether you get allergies
Common substances that trigger allergic reactions include:
Pollen (of trees, grass, weeds)
What are the symptoms of an allergic reaction?
Mild allergic reactions may cause:
Watery, itchy eyes
Runny nose and sneezing
Severe allergic reactions (anaphylaxis Anaphylactic Reactions Anaphylactic reactions (sometimes called “anaphylaxis”) are the most serious, sudden, and life-threatening allergic reactions. You develop severe symptoms such as an itchy rash over your entire... read more ) may cause:
Swollen eyes, lips, tongue, and throat
Wheezing and trouble breathing
Belly cramps, feeling sick to your stomach, and throwing up
Dizziness and fainting because of a drop in your blood pressure
How do doctors tell if I have an allergic reaction?
Doctors can usually tell based on your symptoms and by examining you. However, it can be hard for doctors to tell exactly what you're allergic to. They may do skin tests or blood tests to find out.
How do doctors treat an allergic reaction?
For mild reactions, your doctor may give you:
Corticosteroid nose sprays
For severe reactions, you may need:
A shot of epinephrine
Antihistamines and corticosteroids given by vein (IV)
Medicine and fluids given by vein to raise your blood pressure
Medicine to open your airway and help you breathe
Sometimes a breathing tube down your throat so doctors can put you on a ventilator to help you breathe
How can I prevent allergic reactions?
The most important ways to prevent allergic reactions:
Avoid the things you’re allergic to
If you can't avoid the things you're allergic to, ask your doctor about allergy shots
Avoiding an allergen may involve:
Stopping a medicine
Keeping pets out of the house or limiting them to certain rooms
Using high-efficiency particulate air (HEPA) vacuums and filters
Not eating a certain food
Removing or replacing items that collect dust, such as soft furniture, carpets, and knickknacks
Putting special covers on mattresses and pillows to keep out dust mites
Using synthetic-fiber pillows
Frequently washing bed sheets, pillowcases, and blankets in hot water
Frequently cleaning the house, including dusting, vacuuming, and wet-mopping
Using air conditioners and dehumidifiers in basements and other damp rooms
Getting rid of cockroaches
With allergy shots, the doctor gives you shots of the substance you're allergic to. At first the shots have only a very, very tiny amount of the substance. The amount is too small to cause a severe reaction. Then the doctor gives you shots that have more and more of the substance. That way, your body can become used to the substance and not react to it. Allergy shots don't always work. And when they do work, you may have to keep getting the shots.