Hi Misty,
Welcome to SR. I will try to answer your questions as best I can.
My ex husband is addicted to opiates, including oxycontin. He was abusive to me and our kids, but he was that way all the time. I do think that drugs lower inhibitions and for some people, violence is a possiblity. Are you asking that because your bf is violent towards you or others?
Opiate users develop a tolerance to the drugs, and they will increase the amount they take. They have to if they want to get the same 'buzz'. You might also watch for signs of him snorting them. My ex started snorting them in order to get off faster.
One thing you can bet your life on: if your bf has a drug abuse problem (aka addiction), it WILL get worse. It will not just go away, or simply stay the same. Is there a legitimate reason medically that he is taking oxy or is he just doing it to get high? If the answer is to get high, then he is likely already addicted. Oxy is a very addictive drug.
From my experience, and from the many posts I have read here, I can promise you that he is most likely doing more oxy than he is telling you. That's just the way it usually works..what we know about it just the tip of the proverbial iceberg.
You say you love him and I'm sure you do. But you need to be educated on what you are getting yourself into. Addiction destroys not only the addict but also the people who love him or her. Read around on this board, and you will quickly see what I am talking about.
You can do nothing to change him; you cannot control his drug use. Don't try, because it cannot be done by anyone but him. The only person you can control is yourself. Find out as much as you can about addiction and make an educated decision about whether or not you want to stay in a relationship with an addict.
If he is an addict, he will always be one. He may find recovery, many do. But he will be an addict forever.