What happen if my friend ingest bath salt signs to look for?

Danger. Designer drugs such as mephedrone are falsely labeled as "bath salts" or "plant food" circumventing the law. So far, no one has died or been permanently injured by mephedrone, though we know nothing about long-term effects. Tooth-grinding and excitability are signs. A real friend will tell you the truth if you ask, and will value your friendship over a stupid high.