I am among the 1:4 people diagnosed with mental illness. I have been treated for over 10 years. The only over the counter treatment that I know of is St John's Wort. However, this will not work on all forms of depression, and will only work on mild cases.
The family member in questions does need to speak with a qualified specialist. A psychologist is someone that went to college for 4-5 years and is licensed to counsel. They do not have the ability to prescribe medications.
Your family practictioner can prescribe meds for depression. Due to the drug addiction issues, a good family doctor will refer you to at least a psychiatric nurse practicioner ( also known as a PNP ) It is very important that the pnp is told that you don't want anything that can be addictive. In this case, addiction reffers to a chemical dependancy, not a psychological or emotional one. If the pnp does not feel secure in prescribing because of the known addiction, they will say to go to a psychiatrist. This is WAY more expensive than a family doctor or a pnp. You are looking at $50 or more dollars an hour, plus an attitude problem in most cases. In two states, with about 6 pscychiatrists, I have only met ONE that was worth going to. Only one that would actually LISTEN. They over book, and schedule you for a 15-20 minute appointment and rush you out of the office.
Medical treatment is not enough. It will help get rid of the symptoms of depression, but it will not help with the core reason for the depression. The family member likely turned to heroine because of the depression to begin with. Trying to escape the pain. That is where the psychologist or counselor comes in at. A good one will help their client grow, will help their client establish what the root of the disorders are. It is hard to find a good one. And, I'm not sure the one that is being seen is a good one.
When looking for a therapist, the family member will need to find out if the therapist / counselor / psychologist has experience treating recovering addicts. This is important. The addiction is part of the person, and must also be addressed. Without addressing it correctly, more harm than good could be done. On top of that, if the therapist has an understanding of how addiction works, the family member will not have to struggle as hard to get answers that they are looking for.
There are foods that can be eaten that can help fight off depression. Things that are dark green will help. Brussells Sprouts, kale, collard greens, spinach, and broccoli are all good choices. They will increase the seratonine levels. Low seratonine is a primary cause of depression. Because of the addiction issue, I am more inclined to think the depression is psychological, and not a chemical imbalance. However, the medication would provide some relief of the symptoms.
I hope everything works out. I hope you can find someone that can help the family member. In the meantime, if the person is not already going to Narcotics Annonymous or Alcoholics annonymous, I strongly recommend it. I also recommend the close friends and family of the person to go to look into getting help for themselves so they can better understand what their loved one is going through. Alanon may be helpful.