Holding an intervention without professional help is usually not a good idea, for a number of reasons. The reason behind an intervention is to make the person who needs help want to seek treatment for their problems. If an intervention is held by friends and family without professional guidance the desired end result may not be achieved. Interventions can often include anger, betrayal, and other negative emotions that can create a volatile situation if care is not used. An intervention professional has specialized training and knowledge on how to deal with these situations so that the desired outcome is achieved. The intervention specialist is an independent party who does not have any ulterior motives, and they are there to guide the intervention so that it is productive.
The first instinct that you have may be to get together friends and family members in order to confront the substance abuser, but this may not be wise without advance planning and professional help. The person may get defensive because they feel they are being attacked rather than being offered help, and a professional who has intervention experience can help defuse these emotions before they become an issue. A professional in interventions will understand all of the steps involved with a successful intervention and help you arrange for appropriate treatment if the individual who needs help agrees to go into a program. An intervention is not just for substance abuse either. Eating disorders, compulsive gambling, and other types of addictions may also benefit from a properly planned and executed intervention.