Anecdotal, but Sudafed seems to have literally cured my allergies. I used to have bad allergies and was allergic to dogs/cats and Sudafed was the only thing that would clear my sinuses and allow me to breathe. I would take at least one every day. After a year I no longer needed to take it and I could breathe freely even around cats, dogs!

I don't know how/why it worked that way, but it did. Tell me Sudafed doesn't work and I'll laugh really hard in your face for a long time.