How can you get a known safe drug if it's illegal? If I buy a box of processed food at Walmart I can be pretty damn sure that it is what it says it is. Not so for illicit drugs.
"How can you get a known safe drug if it's illegal?"
This is a great and very important question. There'd be a lot fewer deaths and adverse reactions if more people took it seriously.
For one, you could study chemistry and pharmacology and synthesize the compounds yourself.
Second, you could test the compounds you got. There are testing kits you can buy and testing services (like those done by DanceSafe at festivals), but while they can test for known compounds, they can't test for unknown ones (like many of the new designer drugs that aren't well known yet)... and they generally don't test for potency either.
Third, you could grow or pick some natural psychedelics, like mushrooms, cacti, and various plants. You have to be really careful with this and really know what you're doing or rely on someone who does. Alan Rockefeller's talks on identifying psilocybin mushrooms are great for this: [1]
Fourth, some psychedelics like morning glory seeds, hawaiian baby woodrose seeds, salvia divinorum, and ketamine can be acquired legally in many places. 5-MeO-DMT itself is legal in some places. So where these are legal you should be more assured of their safety -- though you'll still want to make sure the seeds are pesticide-free, for example.
Finally, anyone who cares about safety should be advocating legalization, as it's keeping these substances illegal that makes them less safe and leads to many unnecessary deaths and overdoses.
LSD is unique in that the normal dosage is about the size of a quarter of a postage stamp, or a single drop of liquid. There aren't many contaminates on that scale that can cause harm.
But more generally speaking, a person has to gauge the safety of a drug they buy on their knowledge of the source. Ideally, it's via someone who has purchased from that source before and can vouch for the drugs.
It used to be the case that no lethal drugs were potent enough to be active in the tiny dosages that LSD was distributed in... so you could feel pretty safe in taking it.
Unfortunately, that has not been the case, as there are now very potent and potentially lethal drugs like Bromo-DragonFLY[1] that are active in similar dosages to LSD.
> LSD is unique in that the normal dosage is about the size of a quarter of a postage stamp, or a single drop of liquid.
Both these descriptions of dose are meaningless. A typical dose of LSD is anywhere between 50 and 300 micrograms. But with such a minuscule amount being so potent it is deceptive when considering what a lethal overdose of LSD is. I've heard it said you'd have to literally drown in LSD for it to kill you. I expect the actual lethal dose is an estimation, because even 500x the normal dose is apparently not lethal.