In heroin users specifically, 5% needed either repeat naloxone or oxygen > 2 hours after initial naloxone reversal. Observation for 3 hours may be safer, especially for those with polysubstance abuse.
Management of nerve agent (NA) poisoning requires recognition of the syndrome and availability of the antidote. It is important to remember that besides the classic “SLUDGE” and “Killer B’s,” there is also the nicotinic syndrome which can cloud the clinical presentation. Add the “weekdays” mnemonic for nicotinic effects to your list of symptoms in NA toxicity.