To make meth (methamphetamine) you need some chemicals that are hard to make outside a serious lab and are very controlled.

pseudoephedrine is a good starting place to make meth. It’s the active component in Sudafed hence the name. The good stuff behind the counter has pseudoephedrine the stuff on the shelf doesn’t and doesn’t do anything.

There is more chemistry in pseudoephedrine products to make it hard to turn meth then there is in it to make you feel better.