Contaminants, adulterations and mix-ups: an overview

Ever heard of levamisole, hexamethylenebenzamide or phenacetin? These and many other substances are regularly found in drugs at the DIMS. The DIMS is the national network of test services in the Netherlands. Since 1992 you can go here to have your drugs tested. This is now possible at more than 30 locations in the Netherlands. Read more about how the testing service works here and here. Because the drug market is an illegal market, there is no supervision of the production process. There is also no government quality mark that the drugs must meet, which other medications do have. That is why it can happen that drugs are contaminated or adulterated with substances that do not actually belong in them.

We have made an overview of the most common contaminations, adulterations or mix-ups. Unfortunately, not always something is known about the effects and the risks. But the most important effects and risks that are known are listed below.

An important note beforehand:
This list is not complete. There is a chance that your drugs contain a (risky) substance that is not on this list. Always have your drugs tested and be well informed about any additional substances that have been found in your drug and what the risks are. Drugs with extra substances are not pure and contain more substances than you would like. The risks of these substances differ greatly. If the risks of these substances are greater than the risks of the drugs themselves, the testing service will advise against the use of the drug. If the risks are completely unknown, the test service will also advise against use.

We’ll start with some definitions of words you’ll encounter more often:


When we talk about contaminants, we mean substances that end up in the drug during production. This can happen, for example, because the wrong or contaminated raw material has been used. Or because the production process did not go completely smoothly. The test service calls the latter: ‘by-products’. By-products have inadvertently entered the drug.


Adulterants are products that are deliberately added to make more profit. Some have no psychoactive effect (you don’t feel it). Others have no additional risk, for example certain sugars such as mannitol or inositol. Other adulterants do have a psychoactive effect or a risk. Examples include caffeine or levamisole. Adulterants that don’t have have any effects are also called diluents.

Mix-up or misrepresentation:

In a mix-up, someone can accidentally or on purpose sell something as something else. Then, for example, 2C-B is sold as XTC. Another example of this was selling 4-FA as a speed from 2009 to 2012. Or offering a 4-FA pill containing 4-FMA.

Unknown substance:

Sometimes substances are found that are not yet known to the laboratory of the DIMS. The laboratory can see that these substances are in the drug, but they do not know exactly which substance it is. Those unknown substances are given a number. If substances are common, or possibly very risky, the laboratory can conduct additional research into this substance. This way you can find out which substance is involved.


Amphetamine (speed)

Amphetamine (speed) is mainly used as a drug itself. Although it is regularly claimed that there is a lot of speed in ecstasy, this is rarely found at the test service. In 1997 there was a very small increase. Since then, it has been found in about 1% of all ecstasy pills tested for years. Usually in small quantities.15

Amphetamine’s effects include: increased alertness and self-confidence, reduced fatigue and a euphoric feeling. The unwanted effects of amphetamine are anxiety, feeling panicky, difficulty sleeping and overconfidence.

The main physical effects are mainly increased heart rate, blood pressure and body temperature, decreased appetite and dehydration;8
Like MDMA, amphetamine is a stimulant and the combination with MDMA therefore carries additional risks. Think of increased heart rate, blood pressure, breathing and risk of overheating,8 but also mood swings, sleeping problems and anxiety.9 The combination of MDMA and amphetamine also causes extra brain damage.


Caffeine is the active ingredient in coffee. Caffeine causes an increase in heart rate and blood pressure and can therefore be harmful to your heart and blood vessels in higher doses. Because MDMA and caffeine both have a stimulant effect, the combination of caffeine with MDMA can contribute to a greatly increased heart rate and overheating.7
Getting a dangerously high dose of caffeine isn’t going to happen anytime soon. A lethal dose of caffeine for an adult is estimated to be around 150 to 200 mg/kg body weight. That is equivalent to about 90 cups of strong filter coffee for a man weighing 80 kilos.5
If there is caffeine in your pill, it will probably mainly make you feel a bit more rushed. It is not often that there is caffeine in ecstasy pills. Usually the effect of the MDMA is much stronger than that of the caffeine.

Hexamethylene benzamide

Hexamethylenebenzamide (Hexamid B) is a substance that is used as a flea deterrent in animals. Little is known about the effect of hexamethylenebenzamide in humans. It is possible that hexamethylenebenzamide is formed as a by-product in the synthesis of MDMA from MDA.

The risks are probably smaller than the risks of the drug it comes with (usually 2C-B or MDMA), but we don’t know for sure.

mCPP (meta-chlorophenylpiperazine)

mCPP was originally developed as an antihistamine. These are mainly used as a sleeping aid or to suppress allergies. mCPP turned out not to be suitable for this. mCPP is also used in research into how serotonin works in the brain, because it works almost exclusively on specific serotonin receptors.

In 2008/2009 it appeared on the Dutch drug market in ecstasy pills. This is due to a shortage of MDMA. Producers used it as a replacement for MDMA. From 2010 it is much less common.
mCPP works in the brain, like MDMA, on the neurotransmitter serotonin, but the effects are generally not experienced as pleasant (especially at higher doses). Common effects of mCPP include headache, nausea, dizziness, agitation, confusion, shivering, and anxiety.

The combination with MDMA carries risks. It puts an extra load on your heart and blood vessels. The combination can also increase the risk of a serotonin syndrome because it ensures more release of serotonin.

MDDM (n,n-dimethyl-3,4-methylenedioxyamphetamine)

MDDM is a relatively unknown psychoactive substance. It is very similar in structure to MDMA. Alexander Shulgin describes in his book “PiKHAL- A Chemical Love Story” how you can make MDDM from MDMA. So there is a good chance that the MDDM is a by-product that remains in the MDMA.

MDDM is less strong than MDMA and you will not notice any real psychoactive effects. Shulgin indicates in his book that little or no effects are experienced from the drug, but this remains anecdotal.1

Little is known about the risks of MDDM, but due to similarities in structure, they may be comparable to those of MDMA. MDDM has also previously been found in a victim of an MDMA overdose.2 It may therefore contribute to the risks of MDMA.

PMMA (paramethoxymethamphetamine)

Paramethoxymethamphetamine is somewhat similar to MDMA in effects, but with a few key differences. It takes longer for the effects of PMMA to be felt and it is less strong. It does not have the euforic effects that MDMA has. Suppose you take a pill that contains PMMA instead of MDMA, you will feel the effects less quickly and you may be inclined to take more. You will then receive even more PMMA. While PMMA is already dangerous from a relatively low dose.
Side effects of PMMA include increased heart rate, overheating, dehydration, and stroke. Due to the high body temperature, your organs can no longer function properly. This has all kinds of serious consequences and you can die from it. Quite a number of people worldwide have died after inadvertent use of PMMA. But people have also died in the Netherlands after unintentional use of PMMA. The body converts PMMA into PMA (paramethoxyamphetamine). PMA also has harmful properties for the body.
PMMA has been found several times in the Netherlands in powders and pills since 2010. Usually it was about ecstasy and low amounts. But several pills with high concentrations of PMMA have also been found, such as the pink superman pill. It has also been found in powders on the Dutch drug market.

All in all, a drug with a lot of risks and little to no desired effects. To read more, view the CAM risk assessment on PMMA.

MDMA by-products

These are by-products of the MDMA manufacturing process. The production did not go completely smoothly, so that remnants of the intermediate steps remain. Often the amount of by-products is low. The by-products are undesirable, but very likely less harmful than the MDMA itself.

Unknown 1821

In 2019, an unknown substance was occasionally found in ecstasy pills. It is probably an MDMA-like substance, but exactly which substance it is is unknown. Because it is an unknown substance, the testing service advises against its use.



Levamisole was formerly used as a wormer or as a medicine in the treatment of immune diseases. It has also been used as an adjunct drug in the treatment of colon cancer.10, 16

Does your coke contain more than 10% levamisole? Then its use is not recommended. Do you use cocaine once every 2 weeks or more? Then it is better not to use cocaine at all that contains levamisole. This is because of the side effects on your immune system.

Using levamisole as a drug generally has mild side effects. This can take the form of abdominal pain, nausea, loss of taste and flu-like symptoms. Excessive and prolonged use of this medicine can lead to worse side effects such as severe skin rashes and neutropenia. Neutropenia is a lack of white blood cells in the body, which results in a weakened immune system. Symptoms of this are flu-like, in the form of chills and weakness. But the danger of neutropenia is the weakened immune system that makes you vulnerable to infections.10 If the neutropenia is very severe it is called agranulocytosis.

There are a number of known side effects of the cocaine-levamisole combination, but a large part of these occur mainly with intensive use. As mentioned earlier, neutropenia is a side effect of long-term use of levamisole. This also occurs with the use of cocaine that has been cut with levamisole.

Another possible risk is vasculitis. This is an inflammation of the walls of blood vessels. This is quickly visible in the form of black/purple spots on the skin. The symptoms of neutropenia often only become visible later, because then the immune system must first be weakened. Both neutropenia and vasculitis can be reversed by not ingesting levamisole. This cannot be repaired if permanent damage has already been done by possible infections or damage to limbs due to inflammation in the blood vessels.10

Read more about levamisole on wikipedia or read the CAM report on levamisole.


Phenacetin was developed as a pain reliever and antipyretic. The drug is now no longer used as a medicine because it has side effects: kidney damage with long-term use and possibly carcinogenic.12
It is likely that phenacetin is used as a cocaine adulterant because it has similar analgesic effects. Another reason is that it looks just like cocaine.
The risks of phenacetin are also the reason why it was taken off the market as a drug. This includes: kidney damage, blood abnormalities, and kidney and bladder cancer.9

These risks arise with prolonged and intensive use. The most common and most important risk is therefore kidney damage, manifesting itself in the form of back pain, side pain or difficulty controlling the bladder. The amounts that occur as cutting are probably a lot lower than the amounts that cause the aforementioned complaints. But of course you prefer not to get it in your body.

Furthermore, it is also important to realize that phenacetin, although originally intended for this purpose, is a pain reliever. Because you feel less pain in combination with the cocaine, this can cause extra physical risks.


See also above under MDMA.
In combination with cocaine, it will mainly provide a somewhat rushed feeling.
Caffeine is rarely found in cocaine.

Lidocaine and other local anesthetics

Lidocaine is a drug that is generally used as a local anesthetic. It is also used to treat heart rhythm disorders. The narcotic effects of lidocaine are similar but stronger than those of cocaine and sometimes give the impression of high quality cocaine when rubbed on your gums. Lidocaine does not have psychoactive effects. Compared to levamisole and phenacetin, lidocaine is much less common in the coke samples that are brought to the drug checking service.

At a low dose, lidocaine stimulates the central nervous system, which poses a risk to your heart and blood vessels. This can cause side effects such as nausea, vomiting, dizziness, chills, ringing in the ears and headache. But at a higher dose, this can turn into central nervous system depression.9 Lidocaine enhances the harmful effects that cocaine has on the heart.17
An overdose of lidocaine is possible. The combination of lidocaine also greatly increases the toxicity of cocaine and increases the risk of a heart attack.13

Other local anesthetics found are: procaine, tetracaine, homocaine and benzocaine. But these are rarely found in cocaine samples.

Paracetamol (acetaminophen)

Paracetamol is a well-known and widely used pain reliever. Paracetamol is also found in cocaine as an adulterant. Paracetamol is safe in low doses and is therefore simply sold in the supermarket. At higher doses, more than 4 grams per day for a healthy adult, or with prolonged use, paracetamol has harmful properties. Both cocaine and paracetamol are primarily processed in the liver. This has the effect that intensive use can overload the liver and cause liver failure.14

The amount of paracetamol found in cocaine is generally small and therefore less harmful than the cocaine itself.

Amphetamine (speed)


See also above under MDMA.

If there is caffeine in amphetamine, it will mainly cause a rushed feeling. The combination of amphetamine and caffeine puts an extra burden on the heart and blood vessels.
Caffeine is very common in amphetamine samples. It is by far the most common adulterant in amphetamine.



In chemical structure, it resembles 2C-B. This substance is said to provide mainly some stimulant effects according to Alexander Shulgin, and has virtually no visual and entactogenic effects. Entactogenic drugs, such as MDMA and 2C-B, have an effect on your emotions and your social attitude. 2-bromo-4,5-dimethoxyphenethylamine can also cause disturbed sleep. It is therefore better not to use this substance if you are looking for a 2C-B like effect.

2C-H (2,5-dimethoxyphenethylamine)

This substance has few psychoactive effects, as 2C-H is likely to be broken down by your body before it can have a noticeable effect. 2C-H is mainly used for the production of 2C-B, 2C-I and 2C-N. This substance is probably left over from the production of 2C-B.

However, very little information is available about the effect and harmfulness of this substance.

3,4-Dimethoxyphenethylamine (DMPEA)

DMPEA is a substance very similar to mescaline in structure, but not in effect. DMPEA has an effect in the body that is similar to MAO inhibitors (albeit mild). MAOIs can have a dangerous interaction when combined with other drugs because they inhibit the breakdown of certain neurotransmitters. This allows you to overdose faster and unwanted effects are enhanced. It is not known how much DMPEA is found in the 2C-B samples, so its use is not recommended. It does not give the desired effect, but does increase the risks.

Hexamethylene benzamide

See MDMA above.

Unknown substances

A lot of contaminants have also been found in 2C-B samples for which the Drug Information and Monitoring System has not yet been able to identify a chemical name. Very little is therefore known about these substances. Below are the most common unknown substances. The use of unknown substances is by definition not recommended.

Unknown Substance 1073: This is likely a by-product from 2C-B production. If this occurs, the concentration is always much lower than 2C-B itself. This substance is probably less harmful than 2C-B, but this cannot be stated with certainty.

Unknown substance 1839: nothing is known about this substance.

Unknown substance 1918: nothing is known about this substance.

Unknown substance 1724: nothing is known about this substance.



Occasionally, caffeine occurs as an adulterant in ketamine. The risks of the combination are probably quite small. It may be a burden on the heart. See also MDMA above.


The most common ketamine adulterant is levamisole. High concentrations of levamisole can pose health risks. For more information about (the risks of) levamisole, see the cocaine adulterants above.



In 2023, many 3-MMC samples will contain no 3-MMC at all, but often a different substance: 3-CMC. Very little is known about 3-CMC (3-chloromethcathinone). It probably has similar effects to 3-MMC, but it works a little shorter and less intense. That is why people might take more and the next dose more quickly. Because so little is known, we cannot say anything about the risks.
Read also: What do we know about 3-MMC substitutes.

4-FA (4-FMP):

4-FMA (4-fluormethamfetamine)

Since 4-FA has been on list 1 of the Opium List, the DIMS increasingly encounters contaminants in samples sold as 4-FA. By far the most common contamination with 4-FA is 4-FMA. Since this is an even newer drug than 4-FA, very little is known about its short- and long-term effects. We do know that it somewhat resembles the effects of 4-FA. 4-FMA has a stimulating effect, it strengthens perception and increases endurance. The substance can also induce mild euphoric feelings and feelings of empathy. So it’s a bit closer to speed than 4-FA.

In addition, a number of negative effects and risks are also known. 4-FMA reduces appetite, constricts blood vessels, increases body temperature and heart rate, and dehydrates your body. It can also cause nausea, headaches and palpitations. In addition, delusions and suspicious thoughts can occur. Especially with lack of sleep.

When using 4-FA, which is very similar to 4-FMA, brain haemorrhages and heart failure have also occurred. Whether this also occurs in 4-FMA is not yet known. So do not use these substances if you are known to have heart problems or headaches. If you have a severe headache, seek immediate medical attention.

Read more about 4-FMA on psychonautwiki.



DOC is a drug that comes from the group of psychedelic amphetamines. It therefore has both a psychedelic and stimulating effect. The dosage is very precise, and it is possible to overdose on DOC. It is not known how much DOC is on a papertrip. The lab doesn’t measure the amount. Read more about DOC on psychonautwiki.

DOC is occasionally found in samples sold as LSD. It then present on a papertrip instead of LSD, not together.

Unknown substance 1729

In addition, the DIMS sees that another unknown substance is found besides LSD. This is probably an LSD variant with an extra methoxy group. Very little is known about this unknown substance.

Non-psychoactive adulterants

Not all adulterants are psychoactive. For example, it can happen that there are fillers, binding agents and sweeteners in your drugs. This is especially common with drugs that are produced in pill form. In general, it can be said that there are relatively few risks to report about non-psychoactive adulterants such as fillers, binders and sweeteners (inositol and mannitol, for example). There are also few interactions between these adulterants and the psychoactive substances. It is possible that lactose is used as a filler. The amount of lactose in a pill is generally very low. However, if someone has a (severe) lactose intolerance, it is better not to use drugs in pill form if he / she does not want to run a risk.

By: Ezra, Lea and Raoul


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(15) DIMS jaarbericht 2021

(16) CAM rapportage levamisol

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