Cough and Nasal Congestion - What is the difference in mucinex D and DM?

Mucinex D has guaifenesin and pseudoephedrine.

Guaifenesin is an expectorant. It helps loosen congestion in your chest and throat, making it easier to cough out through your mouth.

Pseudoephedrine is a decongestant that shrinks blood vessels in the nasal passages. Dilated blood vessels can cause nasal congestion (stuffy nose).

http://www.drugs.com/mucinex-d.html

Mucinex DM contains guaifenesin and dextromethorphan.

Dextromethorphan is a cough suppressant. It affects the signals in the brain that trigger cough reflex.

http://www.drugs.com/mtm/mucinex-dm.html