All withdrawal symptoms listed in DSM-IV were asked across all substances. Structured questions covered these symptoms after cessation of use, i.e., the morning after, or within the first few days. Eighteen symptoms were included in this study: anxiety, insomnia, vivid or unpleasant dreams, hallucinations, restlessness, shaking, depressed mood, hypersomnia, psychomotor retardation, and several symptoms of physical discomfort including feeling weak or tired, bad headaches, muscle cramps, runny eyes or nose, yawning, nausea, sweating, fever, and seizure.
