An examination and pathology testing will reveal important information about suitability for treatment, work or travel. It will also help with the prognosis of infectious diseases. All doctors are familiar with of the nature of narcotic use and its medical consequences. A small number may be unsympathetic and judgemental. Another group will simply be unfamiliar with drug addiction or its treatment since, until recently, this has not been covered in the medical course.
Most doctors are open minded and willing to learn.
They also have access to drug and alcohol specialist services and will be guided by their advice. The answer to this question is simpler than it may appear. One should behave exactly as one would on learning of any other serious problem involving a loved one. Just as if the person had diabetes, angina or HIV, it is important not to panic. Try not to judge, even if you have been hurt.