1. Common Allergy Triggers Slideshow Pictures
2. Take the Quiz on Allergies
3. Allergy Proof Your Home Slideshow

Medical Author:

Alan Szeftel, MD

Alan Szeftel, MD

Dr. Szeftel received his Medical Degree from the University of Cape Town Medical School in South Africa. His clinical training was at Groote Schuur Hospital. He completed his Internal Medicine residency at Brigham & Women's Hospital and Harvard University. He is board certified in Internal Medicine, Pulmonary Diseases, Critical Care and Allergy and Immunology.

View Full Profile

Medical Editor:

William C. Shiel Jr., MD, FACP, FACR

William C. Shiel Jr., MD, FACP, FACR

Dr. Shiel received a Bachelor of Science degree with honors from the University of Notre Dame. There he was involved in research in radiation biology and received the Huisking Scholarship. After graduating from St. Louis University School of Medicine, he completed his Internal Medicine residency and Rheumatology fellowship at the University of California, Irvine. He is board-certified in Internal Medicine and Rheumatology.

View Full Profile

In this Article

• Allergy facts
• What does an allergy mean?
• What causes allergies?
• Who is at risk and why?
• What are common allergic conditions, and what are allergy symptoms and signs?
• Hay Fever
• Asthma
• Allergic Eyes
• Allergic Eczema
• Hives
• Allergic Shock
• Where are allergens? Everywhere
• In the air we breathe
• In what we ingest
• Touching our skin
• Injected into our body
• Common Allergy Triggers Slideshow
• Take the Quiz on Allergies
• Allergy Proof Your Home Slideshow
• Allergies FAQs
• Patient Comments: Allergies - Causes
• Patient Comments: Allergies - Describe Your Experience
• Patient Comments: Allergies - Symptoms
• Find a local Asthma & Allergy Specialist in your town
• Allergy Index

Allergic eyes (allergic conjunctivitis) is inflammation of the tissue layers (membranes) that cover the surface of the eyeball and the undersurface of the eyelid. The inflammation occurs as a result of an allergic reaction and may produce the following symptoms:

• Redness under the lids and of the eye overall
• Watery, itchy eyes
• Swelling of the membranes

Allergic eczema (atopic dermatitis) is an allergic rash that is usually not caused by skin contact with an allergen. This condition is commonly associated with allergic rhinitis or asthma and features the following symptoms:

• Itching, redness, and or dryness of the skin
• Rash on the face, especially children
• Rash around the eyes, in the elbow creases, and behind the knees, especially in older children and adults (rash can be on the trunk of the body)

Hives (urticaria) are skin reactions that appear as itchy swellings and can occur on any part of the body. Hives can be caused by an allergic reaction, such as to a food or medication, but they also may occur in non-allergic people. Typical hive symptoms are:

• Raised red welts
• Intense itching

Allergic shock (anaphylaxis or anaphylactic shock) is a life-threatening allergic reaction that can affect a number of organs at the same time. This response typically occurs when the allergen is eaten (for example, foods) or injected (for example, a bee sting). Some or all of the following symptoms may occur:

• Hives or reddish discoloration of the skin
• Nasal congestion
• Swelling of the throat
• Stomach pain, nausea, vomiting
• Shortness of breath, wheezing
• Low blood pressure or shock

Shock refers to the insufficient circulation of blood to the body's tissues. Shock is most commonly caused by blood loss or an infection. Allergic shock is caused by dilated and "leaky" blood vessels, which result in a drop in blood pressure.