Which type of conjunctivitis is not contagious?

Allergic conjunctivitis is characterized by an immune response triggered by allergens such as pollen, pet dander, or dust mites. Since this type of conjunctivitis stems from an allergic reaction rather than an infectious process, it cannot be transmitted from one person to another. People may experience symptoms such as redness, itching, and tearing, but these are due to their immune system's reaction to specific allergens, making allergic conjunctivitis a non-contagious condition.

In contrast, bacterial conjunctivitis is caused by bacterial infection and can easily spread through direct contact with infected eye discharge. Viral conjunctivitis, commonly associated with viruses such as adenoviruses, can also spread among individuals via respiratory droplets or contact with contaminated surfaces. Chronic conjunctivitis can occur due to ongoing exposure to irritants or allergens and may not always be infectious, but the contagious nature primarily relates to its underlying cause, which is typically more aligned with acute forms of conjunctivitis rather than chronic.