There’s no way to give a broad estimate on that. It’s going to vary widely based on source, geographic location, and form (pressed pills vs powder/crystals/rocks).
Pressed pills or “Ecstasy” pills are more likely to have Amphetamine and/or other stimulants like caffeine and piperazines in addition to the MDMA, as they are intended as “rave drugs” for clubbing and dance parties. (Many users actually prefer amphetamine/caffeine in their pills because MDMA alone is more of a psychedelic than an “upper” and can make people want to sit down, look at the pretty colors, and rub each other instead of dance. Piperazines are typically considered “bad” adulterants, even by the crowd who likes amphetamine, and can be very dangerous, especially when combined with other drugs.)
Sometimes, product sold as MDMA (or Ecstasy) will not contain MDMA at all. Common drugs sold as MDMA are MDA (a metabolite of MDMA with similar effects), Methylone, and BZP (a piperazine), though there are many others depending on your geographic location and source.
Regarding geographic location, you can often find reports on government websites. For example, in the USA, I believe the DEA publishes the percentage of seized drugs that are adulterated (or are another drug altogether) by area (I have seen published numbers on their site for certain areas before, but I don’t know if it’s done regularly and I wouldn’t expect out-of-date reports to still be accurate).
However, your estimate of the likelihood of having dangerous adulterants in your MDMA will likely be dominated by your ability to get trustworthy reports of other people who have taken the same “batch”. (Note there are multiple areas for uncertainty here to account for. Honesty/motives of the people reporting + number of reports, ability of the people reporting to tell the difference, is it actually the same batch, and heterogeneity of the batch, to name a few.)
A few sources of this kind of information are:
Seller reviews and track record if you’re buying online
Other people you know personally who have taken the same batch if you’re buying in person
pillreports dot com (website. do NOT use this as your only source of information, as you never know if your pill is actually the one you see reviewed or an imitation)
Chemical reagent tests
If you are buying online, here is a harm reduction strategy: Select a seller with a perfect track record with regard to quality and a large number of reviews. Once you’ve received it, wait until you’ve seen a significant number of reviews from orders placed around the same time as and after you placed yours that are all still positive with respect to quality. This will help protect you from bait-and-switch tactics and should increase your confidence that the reviews you’ve read are of the same batch/product as you’ve received.
A chemical reagent test is a good risk- and harm-reduction measure that can be used in conjunction with any of the other measures. They change color based on the presence of MDMA and common adulterants (obviously sacrificing some of the stuff you’re testing in the process). The most popular test is the Marquis Test. Other common tests include the Mecke Test and the Simons test. (Make sure to check the legality of these “test kits” in your area before ordering/purchasing one.)
Disclaimer (again): Do not do any of these things if it is illegal for you to do so. This is not intended to encourage or enable any illegal activity. I have posted this information in the interest of harm reduction and scholarly interest alone. If you do anything stupid or if any harm comes to you based on this information, it’s not my fault. If you do anything illegal based on this information, I am not in any way responsible and I told you not to do it.
How high is the risk of adulterants with unexpected effects?
There’s no way to give a broad estimate on that. It’s going to vary widely based on source, geographic location, and form (pressed pills vs powder/crystals/rocks).
Pressed pills or “Ecstasy” pills are more likely to have Amphetamine and/or other stimulants like caffeine and piperazines in addition to the MDMA, as they are intended as “rave drugs” for clubbing and dance parties. (Many users actually prefer amphetamine/caffeine in their pills because MDMA alone is more of a psychedelic than an “upper” and can make people want to sit down, look at the pretty colors, and rub each other instead of dance. Piperazines are typically considered “bad” adulterants, even by the crowd who likes amphetamine, and can be very dangerous, especially when combined with other drugs.)
Sometimes, product sold as MDMA (or Ecstasy) will not contain MDMA at all. Common drugs sold as MDMA are MDA (a metabolite of MDMA with similar effects), Methylone, and BZP (a piperazine), though there are many others depending on your geographic location and source.
Regarding geographic location, you can often find reports on government websites. For example, in the USA, I believe the DEA publishes the percentage of seized drugs that are adulterated (or are another drug altogether) by area (I have seen published numbers on their site for certain areas before, but I don’t know if it’s done regularly and I wouldn’t expect out-of-date reports to still be accurate).
However, your estimate of the likelihood of having dangerous adulterants in your MDMA will likely be dominated by your ability to get trustworthy reports of other people who have taken the same “batch”. (Note there are multiple areas for uncertainty here to account for. Honesty/motives of the people reporting + number of reports, ability of the people reporting to tell the difference, is it actually the same batch, and heterogeneity of the batch, to name a few.)
A few sources of this kind of information are:
Seller reviews and track record if you’re buying online
Other people you know personally who have taken the same batch if you’re buying in person
pillreports dot com (website. do NOT use this as your only source of information, as you never know if your pill is actually the one you see reviewed or an imitation)
Chemical reagent tests
If you are buying online, here is a harm reduction strategy: Select a seller with a perfect track record with regard to quality and a large number of reviews. Once you’ve received it, wait until you’ve seen a significant number of reviews from orders placed around the same time as and after you placed yours that are all still positive with respect to quality. This will help protect you from bait-and-switch tactics and should increase your confidence that the reviews you’ve read are of the same batch/product as you’ve received.
A chemical reagent test is a good risk- and harm-reduction measure that can be used in conjunction with any of the other measures. They change color based on the presence of MDMA and common adulterants (obviously sacrificing some of the stuff you’re testing in the process). The most popular test is the Marquis Test. Other common tests include the Mecke Test and the Simons test. (Make sure to check the legality of these “test kits” in your area before ordering/purchasing one.)
Disclaimer (again): Do not do any of these things if it is illegal for you to do so. This is not intended to encourage or enable any illegal activity. I have posted this information in the interest of harm reduction and scholarly interest alone. If you do anything stupid or if any harm comes to you based on this information, it’s not my fault. If you do anything illegal based on this information, I am not in any way responsible and I told you not to do it.