One good decongestant for sinus problems is pseudoephedrine, according to WebMD. Oxymetazoline and phenylephrine are other decongestants that help fight sinusitis. Decongestants come in the form of tablets, liquids, nasal sprays and drops.
Decongestants work by reducing the inflammation of the nasal and sinus mucous membranes, explains WebMD. This happens due to the ability of the decongestants to constrict blood vessels in the nasal and sinus mucous membranes, thereby reducing congestion. Although useful, decongestants may cause breathing difficulty, headaches, dizziness, restlessness and trouble sleeping. Additionally, decongestants may not be suitable for people with conditions such as diabetes, coronary artery disease and hypertension.