Melissa,
Please read the following and get Help for yourself...
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http://www.addict-help.com/crack-addiction.asp
Other complications associated with crack cocaine use include disturbances in heart rhythm and heart attacks, chest pain and respiratory failure, strokes, seizures and headaches, and gastrointestinal complications such as abdominal pain and nausea. Because crack cocaine has a tendency to decrease appetite, many chronic users can become malnourished. Different means of taking cocaine can produce different adverse effects. Regularly smoking of crack cocaine, for example, can lead to hoarseness, chronic coughing and lung cancer. Ingesting cocaine can cause severe bowel gangrene due to reduced blood flow.
Regardless of how cocaine is used or how frequently, a user can experience acute cardiovascular or cerebrovascular emergencies, such as a heart attack or stroke, which could result in sudden death. Cocaine-related deaths are often a result of cardiac arrest or seizure followed by respiratory arrest. The National Survey on Drug Use and Health (NSDUH) estimated the number of current crack users to be over 1,000,000 in 2005.
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Crystal methamphetamine, also known as crystal meth, is a powerfully addictive stimulant. It is associated with serious health conditions, including memory loss, aggression, psychotic behavior, and potential heart and brain damage. Crystal meth is a stimulant which dramatically affects the central nervous system. The drug is easily manufactured anywhere with basic, over-the-counter ingredients. Crystal meth, a form of methamphetamine, is also known as speed, chalk, ice, crank or glass. It is a white, odorless, crystalline powder. Crystal meth’s structure is similar to amphetamine with more of an impact on the central nervous system. The drug releases high levels of the neurotransmitter dopamine into the part of the brain regulating feelings of pleasure. It usually causes increased activity, decreased appetite, and a heightened sense of well-being. It can be smoked, snorted, orally ingested or injected directly into the blood stream. Crystal meth has a very toxic effect on the human body. It is very dangerous and can cause convulsions, permanent severe body damage or death. Because of its stimulating effects, it is a very addictive drug. Chronic use often causes depression, anxiety, fatigue, paranoia and aggressive behavior. Crystal meth is a Schedule II stimulant, which means it has a high potential for abuse and is available only through a prescription that cannot be refilled.
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I know you were asking about your sister,
Hopefully someone will be alone shortly and help you with that a bit more than I could(as I am no expert in health or science issues).
I am a concerned member and I hope you will seek professional Help.
Take Care