This is tough, what type of drugs do you think your brother is doing? Let's no forget that alcohol and tobacco are both drugs and they can both lead to harder substances. Is he doing a little pot or is it something more serious? Even pot can be serious so it might be worth trying to find out. You could approach him, but he is unlikely to come out and admit it straight away by himself.
You need to look for the signs, is there any drug paraphernalia? What about signs and symptoms, try out this website:
Symptoms
This will help you to see if you believe for sure that your brother has a drug habit of some kind. Then the kindest thing might be the approach your parents, it's a horrid thing to do, but probably the best thing to do.
You need to look for the signs, is there any drug paraphernalia? What about signs and symptoms, try out this website:
Symptoms
This will help you to see if you believe for sure that your brother has a drug habit of some kind. Then the kindest thing might be the approach your parents, it's a horrid thing to do, but probably the best thing to do.