Heroin withdrawal lasts on average 1-2 weeks. Antidepressants and analgesics (not opioids) should be purchased and used exclusively in therapeutic doses. And of course, keeping an eye on this person, leaving him alone is quite dangerous, both because of his condition itself and because of the hallucinations that accompany it.
You can call a doctor at home. The person will be taken to the clinic and instilled. And from withdrawal, he can do something to himself. More than once there were cases when people jumped out of the window, etc.