A: Nasal decongestants work by constricting blood vessels that supply your nasal mucous membranes, especially the wing-like structures on the side-wall of your nose called turbinates. There are two types: pills and sprays. Pills (or liquid oral forms) contain the ingredients pseudoephedrine or phelylephrine. Sudafed is a brand name of one of the major over-the-counter cold remedy companies. Many of their products contain either active ingredient or in combination with other cold medications for other symptoms. Some people are very sensitive to these ingredients and taking too much can make you feel jittery. Decongestant nasal sprays can contain either phenylephrine (lasting 4 hours) or oxymetazoline (lasting 12 hours). Be careful not to use these particular sprays for more than three days, as they can be addictive. The safest thing to take on a long-term basis is any form of nasal saline.