Thanks for beating me to the benzo/alcohol warning. Benzo withdrawal is so bad and so drawn out, sometimes with side effects that can take months, if not years to go away, that 2 psychiatrists now have decided not to withdraw me from a medical dependence on benzos, because of concerns about the effects on my physical and mental state.
There is no way I would consider trying to get off of benzos without medical help, not just because of the seizure risk.
The risk with alcohol is not just seizures, but also runaway high blood pressure. That's why chronic alcohol users are always asked in the ER, etc, when they had their last drink so they can be started on medications to prevent the DTs (Delirium Tremens, which is the medical term for alcohol withdrawal syndrome)
How he is handled in detox and rehab really depends on what substances he is using/abusing. With opioids, the withdrawal is pretty much the same, just varies in intensity based on a variety of factors, such as strength of the drug, amount used, length of time used, etc.