People snort cocaine powder through the nose, or they rub it into their gums. Others dissolve the powder and inject it into the bloodstream. Some people inject a combination of cocaine and heroin, called a Speedball. Another popular method of use is to smoke cocaine that has been processed to make a rock crystal (also called "freebase cocaine"). The crystal is heated to produce vapors that are inhaled into the lungs. This form of cocaine is called Crack, which refers to the crackling sound of the rock as it's heated. Some people also smoke Crack by sprinkling it on marijuana or tobacco, and smoke it like a cigarette. People who use cocaine often take it in binges—taking the drug repeatedly within a short time, at increasingly higher doses—to maintain their high.

The brain's reward circuit, which controls feelings of pleasure Cocaine increases levels of the natural chemical messenger dopamine in brain circuits related to the control of movement and reward. Normally, dopamine recycles back into the cell that released it, shutting off the signal between nerve cells. However, cocaine prevents dopamine from being recycled, causing large amounts to build up in the space between two nerve cells, stopping their normal communication. This flood of dopamine in the brain’s reward circuit strongly reinforces drug-taking behaviors, because the reward circuit eventually adapts to the excess of dopamine caused by cocaine, and becomes less sensitive to it. As a result, people take stronger and more frequent doses in an attempt to feel the same high, and to obtain relief from withdrawal. Short-Term Effects Short-term health effects of cocaine include: extreme happiness and energy mental alertness hypersensitivity to sight, sound, and touch irritability paranoia—extreme and unreasonable distrust of others Some people find that cocaine helps them perform simple physical and mental tasks more quickly, although others experience the opposite effect. Large amounts of cocaine can lead to bizarre, unpredictable, and violent behavior. Cocaine's effects appear almost immediately and disappear within a few minutes to an hour. How long the effects last and how intense they are depend on the method of use. Injecting or smoking cocaine produces a quicker and stronger but shorter-lasting high than snorting. The high from snorting cocaine may last 15 to 30 minutes. The high from smoking may last 5 to 10 minutes. What are the other health effects of cocaine use? Other health effects of cocaine use include: constricted blood vessels dilated pupils nausea raised body temperature and blood pressure fast or irregular heartbeat tremors and muscle twitches restlessness Long-Term Effects Some long-term health effects of cocaine depend on the method of use and include the following: snorting: loss of smell, nosebleeds, frequent runny nose, and problems with swallowing smoking: cough, asthma, respiratory distress, and higher risk of infections like pneumonia consuming by mouth: severe bowel decay from reduced blood flow needle injection: higher risk for contracting HIV, hepatitis C, and other bloodborne diseases, skin or soft tissue infections, as well as scarring or collapsed veins However, even people involved with non-needle cocaine use place themselves at a risk for HIV because cocaine impairs judgment, which can lead to risky sexual behavior with infected partners (see "Cocaine, HIV, and Hepatitis" textbox). Cocaine, HIV, and Hepatitis Studies have shown that cocaine use speeds up HIV infection. According to research, cocaine impairs immune cell function and promotes reproduction of the HIV virus. Research also suggests that people who use cocaine and are infected with HIV may be more susceptible to contracting other viruses, such as hepatitis C, a virus that affects the liver. Read more about the connection between cocaine and these diseases in NIDA's Cocaine Research Report. Other long-term effects of cocaine use include being malnourished, because cocaine decreases appetite, and movement disorders, including Parkinson’s disease, which may occur after many years of use. In addition, people report irritability and restlessness from cocaine binges, and some also experience severe paranoia, in which they lose touch with reality and have auditory hallucinations—hearing noises that aren't real. Can a person overdose on cocaine? Yes, a person can overdose on cocaine. An overdose occurs when a person uses enough of a drug to produce serious adverse effects, life-threatening symptoms, or death. An overdose can be intentional or unintentional. Death from overdose can occur on the first use of cocaine or unexpectedly thereafter. Many people who use cocaine also drink alcohol at the same time, which is particularly risky and can lead to overdose. Others mix cocaine with heroin, another dangerous—and deadly—combination. Some of the most frequent and severe health consequences of overdose are irregular heart rhythm, heart attacks, seizures, and strokes. Other symptoms of cocaine overdose include difficulty breathing, high blood pressure, high body temperature, hallucinations, and extreme agitation or anxiety.