My son is 48 he does not use alcohol or drugs and has never smoked.his right hand is swollen and painful what could cause this?

Many things: It is hard to say exactly what the cause is based on what you provided. This could be an injury, infection, inflammatory and the list goes on. I would recommend he see a hand surgeon for an evaluation.

Many Causes: There are many causes of hand swelling including tendonitis, arthritis, auto-immune problems such as rheumatoid arthritis or lupus, trauma, broken bones, lymphatic problems and much more. Obviously, need to have a through history and physical exam, as well as further tests such as xray and labs to help determine or "rule out" certain etiologies (causes).