If an OTC drug was a reliable ctb option, we would have a thread about it already. But also the governments would make it prescription-only after some deaths.
Are you a capable adult? Are you able to read? What exactly stops you from reading about methods before posting a thread like that?
This place seems to be full of kids and trolls. I strongly believe that capable adults should have choice about ending their lives, but not as an impulse "well, I'm too sick of life to even read properly about how could I end it, I'll ask some internet strangers on which OTC drugs to overdose". Would you trust us to order a burger for you, instead of you choosing it? If not, why the hell would you trust us on choosing a method of a suicide attempt?