I wouldn't advice anyone to take multi-vitamins. The reactions they can cause are unpredictable (see more information about this in my book The Key to Health and Rejuvenation (www.ener-chi.com).
In addition, when mucus begins to become harder and more sticky, the breathing capacity is lowered and the heart has to pump blood through the circulatory system faster in order to supply the same amount of oxygen and nutrients to the cells. Fresh ginger tea, as well as warm lemon water with a teaspoon of honey are good decongestants and help break up mucus. The hot ionized water described in my book (s) also help to open up the chest area and help remove toxic substances that otherwise require mucus to trap them.