Allergy: Overview

Poison Ivy, Oak, or Sumac - Cause

Contact with poison ivy, oak, or sumac plants can cause a rash (allergic contact dermatitis). The rash is caused by contact with the oil (urushiol) in these plants. Urushiol is an allergen, so the rash is actually an allergic reac

Poison Ivy, Oak, or Sumac - What Increases Your Risk

People in certain jobs or with outdoor hobbies have an increased risk for contact with poison ivy, oak, or sumac and the resulting rash (allergic contact dermatitis). These people include:

Allergy Risk Factors

Scientists have revised their theories about how and why allergies are on the rise.

Should I take allergy shots (immunotherapy) for allergic rhinitis and allergic asthma?

Allergic rhinitis (often called hay fever) occurs when your immune system overreacts to particles in the air that you breathe—you are allergic to them. Your immune system attacks the particles, causing symptoms such as sneezing and a runn

Allergies: Avoiding outdoor triggers

Allergic rhinitis causes symptoms of sneezing, congestion, and a runny nose. But you can control these symptoms with medicine and by avoiding the things that cause them (allergens). If you are allergic to outdoor allergens, such as pollen

Urticaria, Papular

Pneumonia, Eosinophilic