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

When foods or medications are ingested, allergens may gain access to the blood stream and become attached to specific IgE on cells in remote sites such as the skin or nasal membranes. The ability of allergens to travel explains how symptoms can occur in areas other than the gastrointestinal tract. Food allergy reactions may begin with tongue or throat swelling and may be followed by tingling, nausea, diarrhea, or stomach cramps. Nasal breathing difficulties or skin reactions may also be seen. The two main allergen groups that are ingested are:

• Foods
• Drugs (when taken by mouth): for example, antibiotics and aspirin

Allergy Assist The most common foods that cause allergic reactions are cow's milk, fish, shellfish, eggs, peanuts, tree nuts, soy, and wheat.

Allergic contact dermatitis is an inflammation of the skin that is caused by a local allergic reaction. The majority of these localized skin reactions do not involve IgE, but are caused by cells of inflammation. The rash produced is similar to that of a poison ivy rash. It should be noted that when some allergens (for example, latex) come into contact with the skin, they are absorbed by the skin and can also potentially cause reactions throughout the body, not just the skin. For most people, however, the skin is a formidable barrier that can be only locally affected. Examples of allergic contact dermatitis include:

• Latex (causes IgE and non-IgE reactions)
• Plants (poison ivy and oak)
• Dyes
• Chemicals
• Metals (nickel)
• Cosmetics

Allergic contact dermatitis does not involve IgE antibody, but involves cells of the immune system which are programmed to react when triggered by a sensitizing allergen. Touching or rubbing a substance to which you were previously sensitized can trigger a skin rash.