Ignore the nonsensical bullshit of posters who think an opioid overdose equals near certain brain damage while an SN overdose is safe.
Both ultimately cause death by depriving the brain of oxygen. Survived overdoses in both case generally don't result in brain damage, but there are MANY orders of magnitudes more opioid deaths than from SN, which is why you will hear more cases of brain damage from opioids.
An opioid death is not painful and is rated as 10/10 peacefulness in the PPH (for morphine).
Im so weary of the rampant shitty information on this site from people rehashing opinions or "I heard" rather than commenting from a place of scientific knowledge.