Depends on the type of festival I suppose. Speaking generally though alcohol is by far the biggest contributor towards antisocial behaviour, injury etc at festivals. It’s also the drinker that’s more likely to overdose like you allude to. Drug testing tents in other parts of the world disseminate information about dosage and ways to be safest. They seem to be ban alcohol almost independently of any decisions about drug testing.

If it’s a rave, 100% ban alcohol