Allergic conditions encompass a range of immune system reactions to substances that are typically harmless. Common allergic conditions include asthma, eczema, rhinitis, hay fever, urticaria, and food allergies. Asthma, characterized by inflamed and narrowed airways, leads to breathing difficulties and wheezing. Eczema, or atopic dermatitis, manifests as itchy, inflamed skin rashes, often exacerbated by allergens.

Rhinitis and hay fever, both involving inflammation of the nasal passages, cause sneezing, congestion, and runny nose, usually triggered by airborne allergens like pollen or dust.