An allergy is an overreaction of the immune system to a substance that is usually harmless, such as pollen, animal dander, certain foods, or medications. When a person with an allergy comes into contact with an allergen, their immune system produces antibodies that can cause a range of symptoms, from mild to severe.

The exact cause of allergies is not fully understood, but there are several factors that can contribute to their development. These include:

Genetics: Allergies can run in families, suggesting that there may be a genetic component to their development.

Environmental factors: Exposure to certain environmental factors, such as pollution or tobacco smoke, may increase the risk of developing allergies.

Immune system dysfunction: In some cases, allergies may be caused by an underlying dysfunction in the immune system, such as an autoimmune disorder or immunodeficiency.

Early exposure to allergens: Research suggests that early exposure to certain allergens, such as peanuts or pet dander, may increase the risk of developing an allergy later in life.

Lifestyle factors: Lifestyle factors such as stress, diet, and lack of sleep may also play a role in the development of allergies.

It's important to note that allergies can develop at any age, and the severity of symptoms can vary widely from person to person. If you suspect that you have an allergy, it's important to speak with a healthcare professional for proper diagnosis and treatment.