Often no more than 24 - 72 hours, depending on the frequency of use and the individual's body functions. Marijuana is the exception, staying sometimes from several days to several weeks, again depending on the circumstances. However, through hair analysis, drugs are detectable up to 90 days after drug use. If this sample is confirmed positive, then the balance of the specimen is stored under strict laboratory procedures for future needs. It is held under refrigerated conditions for at least six months.
Every company has different policies.
Some find termination as the only answer for a positive drug screen, as drug use is an immediate breach of company policy. An EAP can be funded by the company or require the employee to fund their own treatment, as long as they can pass subsequent drug screens. Whatever procedure you adopt, the final determination will be the consistency by which you implement your discipline. Some states now require an EAP as part of the company's drug testing policy. Check your state laws for clarification.