death is due to methaemoglobinaemia, and googling for "methaemoglobinaemia survival" brings up
one case of a 23-year-old who survived intentional ingestion of sodium nitrite -- i expect this has been linked elsewhere -- and a case of a
36-year-old who survived poisoning with dapsone (which causes methaemoglobinaemia; and olanzapine, which doesn't). the latter patient was in a coma and required eight days of intubation, respiration, etc. but both were discharged with favourable outcomes.
another dapsone overdose with a favorable outcome in a 3-year-old (again, methaemoglobinaemia).
in the
discussion section of this article from above, several sources are cited listing symptomology, survival, and mortality cases for various MHbA levels. symptoms of methaemoglobinaemia vary between degrees, but seizures are indicated at higher degrees, which may lead to complications as i understand it. re brain damage,
this article reports on a 17-year-old who died of complications including a toxic brain injury resulting from methaemoglobinaemia, as does
this article reporting on a 56-year-old; brain damage [is] inevitable but i couldn't dig up any survival cases.
i'm no science is scary but hopefully i haven't mangled anything too badly. if i have, i will delete this post.