It is a decongestant that works by narrowing the blood vessels in the nasal passages. It is often used to relieve nasal congestion due to allergies or the common cold. It is an antihistamine that helps relieve symptoms of allergies such as sneezing, runny nose, and watery eyes. It can also be used to relieve symptoms of the common cold. It is also a cough suppressant that works by reducing the urge to cough. It is often used to relieve dry, non-productive coughs. The combination of these three ingredients in a single medicine can provide relief from multiple cold and allergy symptoms, including nasal congestion, sneezing, runny nose, watery eyes, and cough. However, it's important to use these medicines as directed and not exceed the recommended dosage, as they can cause side effects such as dizziness, drowsiness, and nausea. It's also important to talk to your doctor or pharmacist before taking any new medicine, especially if you have other health conditions or are taking other medications.