There are two forms of meth, l-meth and d-meth, but it is sold in three forms. The two meth chemical structures are mirror images of each other, much like your left (l-meth) and right (d-meth) hands. Both forms have medicinal uses and, legally, d-Meth is only available by prescription. Vicks and Vapor Inhaler are examples of over-the-counter medications that use l-meth as a nasal decongestant. When used as directed, l-meth does not represent a significant health hazard.
D-meth is a controlled substance and legally is available by prescription to treat attention deficit disorder with hyperactivity (ADHD) and for short-term obesity treatment. D-meth is a central nervous stimulant with effects dependent on a number of factors, such as the dose and frequency. Repeated doses may lead to tolerance and addiction to the desired effects and also affect withdrawal symptoms experienced.
Here are the three forms of meth as it is sold and used:
Powder: a white, odorless, and bitter-tasting crystalline powder, readily soluble in water or alcohol.
Crystal: Users smoke chunks of a very pure form of crystalline methamphetamine called Crystal Meth or Ice.
Rock: Big chunks of the drug, usually found in yellow, white, pink, brown and green are usually ingested orally.