Hello and welcome to Healthcare Magic. Thanks for your query. I understand that you are quite worried about your friend s possible addiction to drugs. Now, the symptoms that you have mentioned such as frequent drowsiness, jitteriness, easy irritability, etc. could be indirect indicators of drug abuse / addiction, but they are not definitive diagnostic symptoms. Especially, considering the fact that he has had a recent rehab for opiates, there are chances that he may be using drugs currently. So, I think you should address your concerns for him. You can speak to your friend and convince him to get tested for drugs and if it turns out positive, you can take him to the local mental health services for professional help / de-addiction. Wish you all the best. Regards, Dr. Jonas Sundarakumar Consultant Psychiatrist