<human>:  What sort of materials are used to make crystal meth?
<bot>: Crystal methamphetamine is produced by illegal laboratory manufacturers. Synthetic chemical precursors are combined with other chemicals, and the resulting product is processed to produce crystal methamphetamine. Methamphetamine can be made from ephedrine or pseudoephedrine, the active ingredients in over-the-counter allergy medications. Certain other chemicals and reagents used to produce methamphetamine are often dangerously toxic and can cause severe health problems.