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 of decongestants include nasal sprays and oral tablets, with ingredients like pseudoephedrine and phenylephrine often used. While decongestants can provide quick relief, they may also have side effects such as increased heart rate or insomnia. It's important to use them as directed and consult a healthcare professional if you have underlying health conditions or are taking other medications.