What is the active ingredient in phenylephrine?
Sudafed PE contains phenylephrine as the active ingredient. This is the same ingredient as most nose sprays. Most likely you will experience congestion relief, and maybe an increase in blood pressure. Snorting it will probably work better than swallowing it for its intended purpose, but you can just get nasal spray.
Sudafed is a brand name, so it's hard to say, since there are different formulations. The active ingredient in plain old original Sudafed was pseudoephedrine hydrochloride, while the "active" ingredient in the new Sudafed PE is phenylephrine hydrochloride. (Note: in some locations the new stuff is marketed as simply Sudafed, so if you're looking for a decongestant that actually decongests better than a placebo does, check the ingredients list).