What is Sudafed? Sudafed is a decongestant that shrinks blood vessels in the nasal passages. Dilated blood vessels can cause nasal congestion (stuffy nose). Sudafed is used to treat nasal and sinus congestion, or congestion of the tubes that drain fluid from your inner ears, called the eustachian (yoo-STAY-shun) tubes.

Sudafed side effects:

  • loss of appetite
  • warmth, tingling, or redness under your skin
  • feeling restless or excited (especially in children)
  • sleep problems (insomnia)
  • skin rash or itching