Amphetamine comes in a variety of forms and varies in its purity.
This is most common form of street amphetamine. It sometimes appears as a white, off white, sometimes pinkish crystal powder. This can be snorted, rubbed on the gums, dissolved in a drink or swallowed (wrapped in a cigarette paper). People may also dissolve it in water and inject it to produce a more powerful high. Injecting drugs carries particularly high risks of overdose, infections, addiction and damage to veins.
In Europe this usually refers to a putty or paste containing amphetamine sulphate. The name is confusing, because amphetamine can occasionally be found in its ‘freebase’ chemical form, an oily liquid, but this is not what is usually meant by ‘base’. So-called base amphetamine is often much stronger than the normal powder kind, although the purity of illegally produced amphetamine is so variable that you never really know.
These come in various colours, shapes and markings. Sometimes pills sold as MDMA (ecstasy) or other drugs may actually contain amphetamine. As with the forms above, purity is variable and often low, with much of the pill being other substances which could themselves be harmful.
There are a range of prescription drugs containing amphetamine, related to amphetamine, or which are turned into amphetamine by the body. These are used to treat conditions such as ADHD or narcolepsy but have been known to end up being used recreationally.