Tetrahydrozoline hydrochloride is widely used in over-the-counter eye drops and nasal sprays due to its vasoconstrictive properties. In eye care, it helps reduce redness and irritation by constricting the blood vessels in the eyes, providing quick relief from minor eye discomfort. In nasal formulations, it is used to alleviate nasal congestion by shrinking swollen blood vessels in the nasal passages, making breathing easier. Additionally, it is sometimes included in topical creams to reduce redness and inflammation associated with minor skin conditions. Its effectiveness and rapid action make it a common ingredient in products designed for symptomatic relief.