Pseudoephedrine is a common, legal drug that is often times found in cold medicines, decongestants, cough syrup, etc. Pseudoephedrine helps relieve symptoms caused by the common cold, flu, sinusitis, infections, or allergies. Most medicine that contains this drug is by prescription only. It is not recom-mended that this drug be used in young children or infants. It can cause long term side effects in a child under four years of age.