There is a wide range of regularly abused synthetic drugs, with some of the more common being ketamine, PCP, bath salts, and GHB. These drugs are created in a laboratory and are purely chemical. Synthetic drugs are becoming more and more popular – in 2009, there were two synthetic cannabinoids in circulation. In 2012, there were a total of 51. Withdrawal from synthetic drugs starts with relatively mild symptoms – insomnia and hypersomnia, difficulty concentrating, changes in mood and appetite, depression, and body tremors. If an individual has been abusing synthetic drugs for an extended period, complications related to withdrawal might arise. These complications could include seizures, spiked heart rate, and increased blood pressure, and they can be life-threatening if the concerned individual is not being monitored 24/7.