Withdrawal symptoms generally occur when one abstains from the use of drugs and alcohol. The brain produces neurotransmitters, which are suppressed by drugs and alcohol. When one stops taking drugs and alcohol, the brain begins producing these neurotransmitters again which results in the appearance of withdrawal symptoms. Emotional withdrawal symptoms include anxiety, restlessness, insomnia, depression and social isolation, while physical symptoms constitute sweating, rapid heartbeat, tension in the muscles, difficulty while breathing, tremor and nausea accompanied by vomiting. Some symptoms can be very dangerous; they are seizures, hallucinations, delirium and even heart strokes. Withdrawal symptoms constitute 2 stages, the first is the acute stage while the second is known as the post-acute stage.