He needs to watch his diet while he is on it. I went on it for a few months and gained a ton of weight because it made me want to eat all the time. It also made me really tired and I had difficulty concentrating. It didn't work for me, but that doesn't mean it won't work for him. Everyone reacts to medication differently so I can't really say how he will react to it. I'd just tell him to pay attention to any side effects he might be experiencing and bring them up to his doctor.