Eyebright (Euphrasia officinalis) has a long history of use in traditional herbal medicine, especially in Europe, for treating various eye conditions and respiratory allergies such as hay fever. The herb has been used for centuries in folk remedies to relieve symptoms like nasal congestion, sinusitis, and allergic rhinitis, largely due to its perceived anti-inflammatory and astringent properties. Traditional herbalists often prepared eyebright as teas, tinctures, or topical applications for respiratory and sinus-related discomfort.

However, scientific validation for the use of eyebright in respiratory allergies is limited. There are very few clinical studies, and most evidence remains anecdotal or based on historical usage rather than modern research. Some laboratory studies suggest that eyebright contains compounds like flavonoids and iridoid glycosides, which could theoretically have anti-inflammatory or antioxidant effects, but robust clinical trials in humans are lacking.

Overall, the use of eyebright for allergies (respiratory) is primarily justified by tradition, not by well-established scientific evidence. Its popularity persists in herbal and alternative medicine circles, but healthcare providers typically do not recommend it due to the paucity of rigorous scientific support.