Pseudoephedrine, an active ingredient in some cold, allergy, and sinus products, can be chemically processed into methamphetamine (commonly known as meth). The illegal use of meth has increased in recent years, prompting Congress to pass the Combat Methamphetamine Epidemic Act of 2006 (CEMA). The objective of the law is to eliminate the use of pseudoephedrine in the illegal production of meth. By law, products containing pseudoephedrine must now be sold behind the pharmacy counter and through online retailers who must meet certain requirements.
Note that products containing pseudoephedrine remain available without a prescription in most states.