But if I mix this shit with alcohol, could it increase its lethality? This has already killed some people.
It will increase lethality but you have to put some things into perspective statistically. Any marginal increase is not very meaningful if we don't account for the actual proportional size of that effect.
E.g., Tripling the odds of dying if the base-rate odds are e.g., 0.1% only puts it up to 0.3%.
I'm not sure the exact odds of successful ctb with codeine or alcohol alone but working off the aggregate statistic of overdose suicides altogether being successful 1-6% of the time, we can assume polydrug suicide attempts are included; especially with alcohol considering it's one of the most accessible and commonly used drugs.
Inferring from this aggregate statistic, I doubt your method is much better than the higher end of this range; being perhaps closer to 6%
I wouldn't count on it considering the likelihood of vomiting and unreliable pharmacokinetics of both drugs, even when used conjointly.
For even just moderate (but far from good reliability still) Stick with stronger opioids used in massive doses preferably via IV or rectal administration; check out my opioid mega thread for more info. Even this method is only moderately reliable and has major confounding issues making it far from reliable even when controlling for drug purity and other vectors of error; the pharmacology of opioids are fundamentally unreliable no matter what peripheral controls you implement.
The
only proven and reliable drug overdose methods that are accessible are SN or inert gasses *when extra-pharmacological factors such as environment, exit bag configuration, or antiemetic regimen* are tightly controlled. A few others are mentioned in the PPH but they typically lose some points on either reliability, comfort/painfulness, and accessibility (e.g., nembutal)