Your friend is toast! (Wy not use Sudafed to dry it up?)
You're probably thinking of an antihistamine like Benadryl or Claritin for post nasal drip, runny nose, sneezing. However, they both have a small effect on nasal cavity congestion (mucus buildup).
Sudafed is mostly for nasal congestion. It has a minor effect on the liquid mucus nose stuff. I've had my share of colds in my days and definitely know the difference.