Have you ever had to deal with a patient with a history of substance abuse or addiction?

Yes both.

every day .... likely that person who comes in and has high blood pressure and is a bit anxious but their BP at home is normal "I don't understand?" ask about their drinking history in a non judgmental way. I have had a LOT of paints who go to their normal provider after they have stopped their routine alcohol intake for a day or two so the provider doesn't smell the alcohol. Their BP is high and is ignored as artifact when the truth is they are in alcohol withdrawal, need withdrawal management or referral but no one asks the right questions.
OR many primary care providers are afraid to ask about substance use, do not want to bother with those (**& adicts, If you ask about their consumption in a non judgement was what their intake happens to be (even state " I have to ask, I am not judging, the answer is what the answer is though, I cannot properly care for you if you are not giving me true answers.) usually they want to tell the truth but are waiting to be asked.

treat them as someone with a disease process, treat them as person. They have done some "interesting things" you likely have never experienced. Treat them non-judgmentally as if their issues are part of the process and guide them.

It is shame and guilt, guilt and shame that has been heaped on them that crush their recovery.

end of rant ---sorry [well not really]

Many, many time as an RN on the med/surg floor, they usually will send them to medical first to detox safely then figure out a long term psychiatric intervention/plan. By the time they come to us they are usually dealing with more than detoxing, sometime pancreatitis for alcoholic patients, or sometimes some type of cellulitis or osteomyelitis for patient who are intravenous substance abusers. I feel like you treat them as you would any other patient, be supportive and manager their symptoms.