If you use often and for a long time you may:

• Become dependent on speed (see 'Tolerance and Dependence')
• Become violent for no apparent reason
• Get sick more often because you're run down and your body isn't as resistant to disease
• Be easily upset or depressed
• Have periods of psychosis
• Have abnormal eating patterns
• Have problems with your personal relationships, work, money, legal hassles or housing problems.