A nasal decongestant is a type of medication that helps relieve nasal congestion, which is often caused by colds, allergies, or sinus infections. These medications work by narrowing the blood vessels in the nasal passages, reducing swelling and allowing for easier breathing. Common forms include nasal sprays and oral tablets. Nasal decongestants can provide quick relief, but they should be used cautiously. Overuse, especially of nasal sprays, can lead to rebound congestion, where symptoms worsen after stopping the medication. It's important to follow dosage instructions and consult a healthcare professional if symptoms persist.