Used primarily as a nasal decongestant and eye drop to reduce redness in the eyes. It works by constricting blood vessels, which helps relieve swelling and irritation in nasal passages and eyes. Commonly found in over-the-counter cold and allergy medications and eye drops for temporary relief of minor eye redness. Also used in veterinary medicine for similar purposes. Misuse or overuse can lead to rebound congestion or irritation.