How can you put in the picture if a friend that close to you own a drug craving?

How can you put in the picture if a friend that close to you own a drug craving?
if you are close to them, you'd know...
behaviors, hygiene and manners all revise. mood swings, track marks, etc. it depends on the drugs they're taking.
contained by their actions and the road they talk when on a drug
Watch for irrational behavior and frequent disappearances. Also never have any money for gedunks. Pops
Secretive, unusual sleep patterns, innovative mood swings, change surrounded by friends, wieght loss or eating change. Depends on the drug really.
Never having money is other an issue with addict. Also, they rarely keep hold of commitments, for example, telling you they will come together you and not showing up. Depending on the type of drug, the way their eyes look and self changes.