If your doctors would buy that you overdosed on sodium nitrite thinking it was a health supplement, especially when you have no food in your stomach and took anti emetics, then I'd immigrate ASAP.
No, they won't buy it. No, they're not stupid.
A better alternative would be to put it in a salt container and say you stored it there for some unknown reason, then mistook it for salt. Even then they're still very, very unlikely to believe you. You're just gonna get yourself longer in the psych ward.
I told the truth and didn't even get put in the psych ward, so I'll stick with that personally