Diagnosis is finding out about the causes of your problems and/or condition. This is usually done by excluding some possibilities, testing some others and finally arriving at a diagnosis. This is, in some sense, the first step toward solving the problem, or at least reducing it as much as possible.
A confirmed diagnosis is the basis for rational treatment planning and for making the best possible decision for choosing treatment options that are best for your situation and priorities. The process of arriving at a confirmed diagnosis, in addition to a thorough medical examination and exploration of your medical history, usually includes the use of a range of diagnostic methods and procedures. Exactly what is required in this process depends on the initial suspected conditions and on the findings of initial tests.
Some diagnostic tests and procedures not only confirm (or exclude) a diagnosis, they also contribute toward treatment planning. Depending on your diagnosis and the time scale of planned interventions and actions, this is the time when you can begin to help yourself by considering your use of recreational and other drugs: you may consider giving up smoking and/or drinking or the use of other non-prescription drugs. Taking such steps can make a very positive contribution toward optimal treatment outcomes.