Allergies occur when your immune system reacts to a foreign substance such as pollen, bee venom or pet dander.
Your immune system produces substances known as antibodies. Some of these antibodies protect you from unwanted invaders that could make you sick or cause an infection. When you have allergies, your immune system makes antibodies that identify your particular allergen as something harmful, even though it isn't. When you come into contact with the allergen, your immune system's reaction inflames your skin, sinuses, airways or digestive system.
The severity of allergies varies from person to person and can range from minor irritation to anaphylaxis — a potentially life-threatening emergency. While allergies can't be cured, a number of treatments can help relieve your allergy symptoms.
Allergy symptoms depend on your particular allergy, and can involve the airways, sinuses and nasal passages, skin, and digestive system. Allergic reactions can range from mild to severe. In some severe cases, allergies can trigger a life-threatening reaction in your body known as anaphylaxis.
Hay fever, also called allergic rhinitis, may cause:
Atopic dermatitis, an allergic skin condition also called eczema, may cause:
A food allergy may cause:
An insect sting allergy may cause:
A drug allergy may cause:
When to see a doctor
For a severe allergic reaction (anaphylaxis), call 911 or your local emergency number or seek emergency medical help. If you carry an epinephrine auto-injector (such as EpiPen, EpiPen Jr or Twinject), give yourself a shot right away. Even if symptoms improve after an emergency epinephrine injection, a visit to the emergency department is still necessary to make sure symptoms don't return when the effects of the injection wear off.
If you've had a severe allergy attack or any signs and symptoms of anaphylaxis in the past, make an appointment to see your doctor. Evaluation, diagnosis and long-term management of anaphylaxis are complicated, so you'll probably need to see a doctor who specializes in allergies and immunology.
An allergy starts when the immune system mistakes a normally harmless substance for a dangerous invader. The immune system then produces antibodies that are always on the alert for your particular allergen. When you're exposed to the allergen again in the future, these antibodies release a number of immune system chemicals, such as histamine, that cause allergy symptoms.
Common allergy triggers include:
You may be at increased risk of developing an allergy if you:
Having an allergy increases your risk of certain other medical problems, including:
Preparing for your appointment
If you're experiencing symptoms that may be related to an allergy, start by seeing your family doctor or general practitioner. Because appointments can be brief, and because there's often a lot of ground to cover, it's a good idea to prepare for your appointment.
What you can do
Preparing a list of questions will help you make the most of your time together. For symptoms that may be related to an allergy, some basic questions to ask your doctor include:
In addition to the questions that you've prepared to ask your doctor, don't hesitate to ask questions during your appointment at any time that you don't understand something.
What to expect from your doctor
Tests and diagnosis
To evaluate whether you have an allergy, your doctor may:
If you have a food allergy, your doctor may:
Your doctor may also recommend one or both of the following tests:
If your doctor suspects your problems are caused by something other than an allergy, you may need other tests to identify — or rule out — other medical problems.
Treatments and drugs
Allergy treatments include:
Lifestyle and home remedies
Some allergy symptoms improve with home treatment.
The following herbs may be of some benefit in treating allergies:
More research is needed before these therapies can be recommended as safe and effective. If you're interested in adding alternative therapies to your treatment plan, always talk with your doctor first. He or she can help you understand which therapies are most likely to help in your case. Your doctor can also provide information about potential health risks and drug interactions.
Preventing allergic reactions depends on the type of allergy you have. General measures include the following:
Last Updated: 2011-01-28
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