Tetryzoline is primarily used in the medical and pharmaceutical fields as a vasoconstrictor. It is commonly found in over-the-counter eye drops and nasal sprays to relieve redness and congestion. In eye care, it works by narrowing the blood vessels in the eyes, reducing redness caused by minor irritation or fatigue. In nasal applications, it helps alleviate nasal congestion by shrinking swollen blood vessels in the nasal passages, making breathing easier. It is also occasionally used in combination with other medications to enhance their effectiveness. However, it is important to use it as directed, as prolonged or excessive use can lead to rebound congestion or irritation.