One of the most pernicious effects for those who become regular users of cocaine is that increasingly more of the drug is required to experience the high.
Chronic cocaine users will crave it and continue using it even though it ceases to produce any real effect. Some addicts experience noticeable spastic tics that result from the brain’s depletion of dopamine. Less common is a type of psychosis called formication where users hallucinate insects crawling under their skin, driving some to try to cut the bugs out with tweezers or a knife.
Physically, prolonged cocaine users can end up with intestinal damage and stomach ulcers. Cocaine affects the heart, causing palpitations. While marijuana also increases the heart rate, taking the two together can increase it by 50 beats per minute. An overdose of cocaine may cause seizures, respiratory or heart failure, stroke, or cerebral hemorrhage, and can be fatal. Cocaine is often consumed with alcohol, eliciting a more intense high and increasing the risk from sudden overdose death by 25 times. Biochemically, this results as a new chemical, cocaethylene (cocaine and ethanol) forms in the liver and penetrates the bloodstream and brain faster.
Unlike the recently discovered Naloxone for heroin, there is no antidote for cocaine overdose, nor is there any specific treatment like methadone maintenance as there is for opiate addiction. Cocaine addicts must adhere to the arduous process of traditional treatment (see Treatment), which initially requires quitting cold turkey.
Short of overdosing, one study based on calls into a drug hotline found the most common symptoms from extended cocaine use to be severe depression (85%), paranoia (65%), memory lapse (40%), violent behavior (31%) and suicide attempts (18%). One of the more subtle but enduring effects from prolonged cocaine use is simply the inability to experience pleasure from everyday activities. Referred to as anhedonia, it can lead to depression and ultimately suicide.