What can I do to help my older brother going through drug withdrawal?

He’s been acting very anxious. I’m not sure if he’s still on whatever he’s on or not but what can I do?
Updates
10 mo
Im pretty sure its marijuana or nicotine
Updates
10 mo
I just want my brother back. I don’t think it’s only drugs but also work and friendships
What can I do to help my older brother going through drug withdrawal?
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