- Impaired control: the experience of a craving or strong urge to use the substance; desire or failed attempts to cut down or control substance use.
- Social problems: substance use causes failure to complete major tasks at work, school or home; social, work or leisure activities may be cut back or given up entirely.
- Dangerous use: substance is used in unsafe settings; continued use despite known problems.
- Drug effects: tolerance (need for larger amounts to get the same effect); withdrawal symptoms (different for each substance).