Nasal decongestants are medications designed to relieve nasal congestion caused by colds, allergies, or sinus infections. They work by narrowing the blood vessels in the nasal passages, which reduces swelling and allows for easier breathing. Common forms include nasal sprays and oral tablets. These medications can provide quick relief, but they should be used cautiously. Overuse 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 or worsen.