Cocaine is a crystalline tropane alkaloid derived from the leaves of the coca plant. It was first used in the 1880s as a local surgical anesthetic and later became an ingredient in many tonics to treat a variety of ailments. It was banned in the United States during the early twentieth century, and it is now classified as a Schedule II drug, meaning it is very powerful and is highly addictive. Cocaine is the second most commonly used illicit drug in the United States with an estimated 1 million users per year. According to U.S. government figures, the number of people dependent on or abusing cocaine in 2012 was 1.1 million, higher than the 821,000 in 2011, and similar to the 1.1 million and 1.0 million in 2009 and 2010, respectively. There are two main types of cocaine: a white, powdery substance used for snorting or injecting; and a smoking version, which looks like a small rock or chip referred to as crack cocaine because of the crackling sound it makes while being heated. Cocaine users experience a strong, euphoric feeling upon taking the drug followed by feelings of depression, anxiety and paranoia. Its affects can last from 20 minutes to several hours, depending on the dosage, purity and method of intake. There are numerous short and long-term effects associated with cocaine. The initial signs are hyperactivity, restlessness, increased blood pressure, increased heart rate, and euphoria, often followed by feelings of depression and a craving to use again. Side effects can include paranoia, impotence, insomnia and loss of appetite. Long-term users can experience itching, hallucinations, paranoid delusions, violent mood swings, depression and a degrading of the cartilage between the nostrils. When overdose occurs, an individual may experience seizures, followed by respiratory and circulatory depression, which can lead to death from respiratory failure, stroke, cerebral hemorrhage and/or heart failure.