There have been several deaths caused by PMA, a potent and highly neurotoxic hallucinogenic amphetamine, which is solicited and sold as Ecstasy.
The acetaminophen component in Lortab can on its own cause a fatal overdose. High doses of acetaminophen can cause liver damage, and dosages should never exceed 4000 mg a day. Acetaminophen is metabolized solely by the liver, so there is a risk of fatal overdose due to hepatotoxicity when Lortab is mixed with alcohol.
The acetaminophen component in Vicodin can on its own put the user at risk of overdose.
Large amounts of opiates, like heroin, can cause the respiration to shut down completely.