Asthma varies significantly in causes, age of onset, and severity. Wheezing, forceful cough, shortness of breath, and chest tightness are telltale signs.

The symptoms associated with pet allergies – coughing and sneezing – are not unique and often can be mistaken with an allergic reaction to pollen.

Mast cell disorders occur when mast cells either are overabundant in number or overreactive in nature and release too many chemicals at once.

Here are three main plant culprits that set off seasonal allergies every year: blooming trees in the spring, grasses in the summer, and then weeds in the fall.

A drug allergy is the abnormal reaction of your immune system to a medication. It can be developed even to a medication you’ve been taking for years.

 Anaphylaxis is a severe allergic reaction that can be fatal if appropriate steps aren’t taken immediately. The most common triggers are food.

Eight foods cause 90 percent of all food allergies. These are eggs, milk, nuts, peanuts, fish, shellfish, soybeans, and wheat. Food allergies can develop at any age.

Allergies are a major cause of illness in the U.S. As many as 50 million people have allergies. An allergic reaction can take a number of forms.

Hives appear suddenly as red raised itchy welts of varying sizes on the skin. They're not contagious and in most cases, the reaction will last only a few hours.

Allergy to insect stings (such as bees, yellow jackets, wasps, hornets, and fire ants) also called venom allergy can cause itching, swelling, hives, and anaphylaxis.

Contact dermatitis is a skin reaction to substances your body is sensitive to. It’s very common and affects almost everyone at some point in their lives.

Patients with immunodeficiency typically experience stereotypic patterns of recurrent infection, which provide clues regarding which portion of the immune system is affected.