What is a common example of a decongestant?

Pseudoephedrine is a common example of a decongestant because it works by narrowing the blood vessels in the nasal passages, which helps to reduce swelling and congestion. This action makes it effective in relieving nasal congestion associated with colds, allergies, and sinus infections. Decongestants like pseudoephedrine are often found in combination products that target multiple symptoms of upper respiratory tract infections.

The other options listed serve different purposes: guaifenesin is an expectorant that helps loosen mucus, codeine is an opioid used primarily for its pain-relieving and cough-suppressing properties, and fluoxetine is an antidepressant that belongs to the selective serotonin reuptake inhibitor (SSRI) class, used for managing depression and anxiety disorders. Each of these medications is effective in treating their intended conditions, but they do not function as decongestants.