One reason it's not talked about more especially in pro choice or suicide planning spaces is that it's unpredictable by design. The combination of a CNS depressant with a stimulant pushes the body into extreme, competing states. Heart rate, blood pressure, and respiratory function are pulled in opposite directions, which can lead to sudden cardiac arrest, arrhythmias, or respiratory failure.
The lack of consistency is part of why it's used more in impulsive or substance facilitated attempts than in planned, controlled exits. It's not a reliable method for someone seeking peace, certainty, or minimal trauma to others. There's also the high potential for surviving with severe damage (brain injury, heart failure, etc.) if intervention happens even slightly too early.
That said, its omission from mainstream discourse is also political. Media coverage of the "opioid crisis" often erases polysubstance use entirely, to fit a narrative that blames opioids alone rather than addressing the broader issues—poverty, chronic pain, inaccessible mental healthcare, or the criminalisation of drug use. It's cleaner to say "opioid overdose" than to unpack the layers of pain and instability that lead someone to mix heroin with meth or fentanyl with cocaine.
So it's not that this combination isn't known—it's that it's inconvenient to talk about. Both in media, where it complicates the narrative, and in suicide discourse, where it doesn't fit the criteria of a clean, reliable, low intervention method.
The "best" ones I know of are Fentanyl + Methamphetamine, Heroin + Cocaine, Fentanyl + Cocaine, Oxycodone + Amphetamines, Morphine + MDMA.
They're just unpredictable and stimulants wear off faster than depressants, causing delayed respiratory collapse. There's a high risk of non fatal use which leads to brain damage, seizures, or locked in syndrome. And, well...It's intervention sensitive as I said. Some do use it intentionally, and successfully, but it's not a method that lends itself well to planning.