Eyebright is a plant. The parts that grow above the ground are used to make medicine.
Eyebright is taken by mouth for swelling (inflammation) of the nasal cavity and sinuses (rhinosinusitis), allergies, hay fever, and many other conditions, but there is no good scientific evidence to support these uses.
Despite the serious risk of infection, some people apply eyebright directly to the eye for conjunctivitis, eyelid swelling (blepharitis), and eye fatigue.
In foods, eyebright is used as a flavoring ingredient.