Sudafed nasal decongestant is the best over-the-counter source of sinus pain relief, as identified in a 2013 article in Men's Health. Its chief active ingredient, pseudoephedrine, is superior to the common alternative, phenylephrine.
Sudafed contains other active ingredients including acetaminophen, chlorpheniramine maleate and four additional pain reducers, according to the Sudafed website. It also explains that the product works by shrinking the blood vessels in sinus areas. Once the blood vessels shrink and the sinuses narrow in size, swelling subsides, and normal breathing resumes. The site also notes that its main ingredient is a component of the drug crystal methamphetamine; ID must be shown before purchase. Recommended dosage is two tablets every four to six hours, with a limit of eight tablets in 24 hours.