I love this question and feel it deserved a longer write up. Please excuse some of my tangential or turgid writing style, I do have a disability that makes this more of a process so please forgive me. I've added sections to skip to the end if you prefer.
Long Story Long re Impurities and Adulterants like Fentanyl in Stimulants:
Personally, I have used quite a bit of melth.@mpfet a mine and all the adDress clinical med.icautions I have been Rxed over decades. Method acting is my favorite for therapeutic and functional daily use for quite some time. Dextro enantiomer amfet is pretty much the same to me as desoxyn, but for improved pharmacokinetics and pharmacodynamics of the latter. Unfortunately, not much desoxyn prescribed anymore despite the favorable response I had briefly years ago. one vendor here used to talk about compounding and such, my crazy friend that I miss now and could not afford to go for that just for the assurance of purity and potency.
That said, it's off to find the best of the worst street alternative and I have never found fentanyl or felt fentanyl was in any Met.h-amp of various qualities and sources. The stuff flooding the border is very similarly produced and most batches can be recognized by the physical inspection and the general miscible qualities of any "extras"...be they leftovers from production that never were cleared out or added in along the way in the chain of supply and distribution...to me, if it isn't added from Mexico origin batches the ice packs in the mom and pop shops in the states are less likely to uniformly practice it, but each is so disconnected and often regional so it's impossible to say. I could see some additive meant to reduce the peripheral nervous system sides and calm the central nervous system for people really doing too much dreaming up in the clouds all day and night, I guess, but mostly F seems to be the opposite of the typical stim users desired effect. We know what we are getting into and it's not like Fent hasn't been around...this is only a problem as it was the next best replacement for a enforcement game plan identical to the last failed 17 thousand enforcement plans for substances in a moral panic or, occasionally, a real crisis in that most of the damage and death needn't have occurred to people.
The war on opioids was predictably just a war on the current stable, customary and more predictable dose and product purity/potency for opiods/opiates in this nation. Immediately the problem gets far worse when Pharma pills are counterfeit and people don't know what or how much to take and just go ahead with the norms they had adapted to and sadly, well...we see what happens. If fentanyl was even more desired than other pain meds that we first declared a war to eradicate some years ago now, it would be the top drug since it's major release and widespread adoption in the medical system since the 80's at least. The fact is, on a mg per mg comparison the respiratory depressive effect is more powerful - same with LSD and shrooms, scarcely a couple hundred micrograms versus a few grams of the two are a reasonable comparison for an equally intoxicating psychedelic.
Most opioid and opiates are far more risky and dangerous in a clinical profile - hence why Fent is used for most of these purposes. When the dose is proportionately low it is less euphoric, less habit forming and addictive, less risky for respiratory depression, and about the same risk in combination with most other CNS depressants, though not all drugs that may end up in combination, but to be blear there is a definite zero tolerance rule everyone needs to have mixing CNS depressants with respiratory depressive side effects, especially if they can lead to death.
Takeaway Thoughts:
-War on opioids is an unfortunate war on the already poor education on risk assessment and harm reduction users of these substances receive.
-These users are not adapting to the new, less reliably consistent alternatives and the media narrative is not coherent and just more confusing, offering a reason for users to reduce their alarm knowing how time and again these things are blown out of the realm of truthful risk messaging to the public and strictly attempt to fear-bully people from these drugs. It works for some moments and always blows back at us.
-Fentanyl isn't in any stimulant in any form and from any substituted amphetamine - RC's, meds, meth.amfet@amine, most of all - where it would be most susceptible to adulteration, one supposes - BUT, that is from anectData and n=1 for my reporting capacity.
-logically, if meth were to have a better chance of sales or higher profit margin with fentanyl sneaked in, there is no reason this wouldn't be a practice going back dozens of years since fentanyl is not exactly fresh of a FDA approval for a New Drug Application - it's as old as anything in the arsenal so why start adding to stimulants now?
-all Pharma amphetamine medications sold outside a pharmacy under a lawful prescription from a licensed MD are nearly guaranteed to be some mix of racemic amp or meth or a few uppers if active at all. Don't buy prescription stimulants that you can't trace to a pharmacy yourself, all lawfully of course!
Personal Note re Use Generally and re Adulterants/Impurities:
IF you make the same mistakes as many people with disorders of cognitive function or psychiatric diagnosis as I have, please try to stick to what is available lawfully and work with a therapist, coach, and other support personnel to manage your condition as an adjuvant to your stimulant medication. I do personally believe desoxyn should be trialed in more patients...I have cognitive disorders from TBI and I cannot find a doctor outside the VA system these days willing to discuss that as a treatment for me despite the simple truth that in my case it is the most reliable and effective treatment I have.
As such, it's been my value choice to find alternative sources and I discourage this for people unless they truly do their homework and know it is worth the risk to them. the law will not agree always so even if you are improving medically, you are risking much and I need to say this despite my general championing of the infamous substance I've used for years with some frustrations at impurities and adulterants here and there, but much time helps me know the main agents for bulking the weight up and one is less desirable but both seem relatively harmless, especially MSM, but I don't know these long term effects or the actual chemical analysis. Every Fen test has not detected that drug and I've never bothered testing beyond that.
Final Note:
It looks to be safe to say "buyer, beware at all times", but don't be too shook by media or sensational reporting. I think it is probably more appropriate to say "buyer, be aware at all times." Besides Fent., there are many more productive ways to ensure you reduce risk of hazard with your use and you should focus on those before worrying about fentanyl - or else don't do these things at all.
As for my wishes for all: buyer, be well and be safe at all times in your journey towards healing, whichever direction it currently is taking your health I wish and know you will end trending towards healthy and happy and drug free one day. Cheers until then.