'I think my co-worker is on drugs.'

With studies estimating that seven percent of the U.S. population is addicted to drugs or alcohol, chances are that many people one day will have to deal with an addicted co-worker, employee, or even supervisor. If so, when and how should one intervene?

Each situation calls for individualized handling, but there are some guidelines that can be followed, suggests Sarah Rahhal, coordinator of the Employee Assistance Program, University of Oklahoma Health Sciences Center. "When [individuals] feel they should confront a co-worker or boss, the first thing they should do is analyze their own motives. Are they a friend of this person, as well as a co-worker? Do they genuinely want to help this person, or are they more interested in getting [him or her] in trouble? Remember, denial is so much a part of this type of disease that direct confrontation often does not work."

For supervisors, the rules are a bit more clear-cut. When work performance is declining, the supervisor simply can document incidents and then talk to the employee and say something like: "This is what I've noticed about your performance, and this is what needs to change. Is there anything I can help you with to achieve this or anything you want to talk about?"

The most common symptoms of drug or alcohol addiction include mood swings, tardiness (especially the "late on Mondays" syndrome), excessive sick leave, extended lunch breaks, irritability, withdrawal, hand tremors, a decrease in the quality of work, and an increasingly unkempt appearance. Sometimes, fellow employees may be able to smell alcohol, marijuana, or other substances on the person's breath or clothing.

"Keep in mind, however, that it's not appropriate for...