Cocaine is most commonly cut with cheap, white powders like sugars and starches, but it also frequently contains pharmaceutical additives like local anesthetics and, increasingly, dangerous contaminants like fentanyl. Despite widespread beliefs about exotic or toxic cutting agents, forensic analyses consistently show that the majority of adulterants are relatively benign substances used to add bulk. The exceptions, however, can be life-threatening.
Bulking Agents: Sugars, Starches, and Powders
The most basic category of cutting agents exists purely to increase weight and volume. These are inert substances that look and feel similar to cocaine powder. Forensic analyses of seized cocaine samples have identified carbonates and bicarbonates (like baking soda) in 42% of samples, lactose in 29%, mannitol in 26%, sucrose in 15%, glucose in 12%, dextrose in 8%, and starch in 3%. These substances are legally available, inexpensive, and generally don’t cause serious harm on their own, though they can irritate nasal passages.
Despite average cocaine purity in the U.S. sitting around 84%, that remaining 16% has to come from somewhere. For street-level dealers, adding a sugar or starch that dissolves easily and blends seamlessly with white powder is the simplest way to stretch a supply. Many dealers themselves report using glucose or mannitol as their go-to cutting agent.
Local Anesthetics That Fake Purity
Cocaine numbs tissue by blocking nerve signals, and many buyers test quality by rubbing a small amount on their gums. This creates a strong incentive to add other numbing agents. Lidocaine, procaine, and tetracaine are local anesthetics commonly mixed into cocaine specifically to pass this “tongue test.” They mimic the numbing sensation, making diluted cocaine feel stronger than it actually is.
Lidocaine is one of the most frequently encountered pharmaceutical adulterants in seized cocaine. It’s cheap, widely available, and dissolves into powder easily. While these anesthetics are generally safe at low doses (lidocaine is used in dentistry every day), they add cardiovascular risk when combined with cocaine. Both cocaine and lidocaine affect heart rhythm, and the combination can amplify that danger in ways a user wouldn’t anticipate.
Levamisole: The Most Common Active Adulterant
Levamisole is a veterinary deworming drug that has become the single most frequently detected active cutting agent in cocaine worldwide. It was pulled from human medical use in the U.S. in 2000 because it caused a dangerous drop in white blood cells, a condition called agranulocytosis that leaves the body unable to fight infections.
There are several reasons levamisole became so popular in the cocaine supply. It physically resembles cocaine, making it effective as a bulking agent. More importantly, the body converts levamisole into a compound called aminorex, which acts like a mild amphetamine. This metabolite kicks in as cocaine’s short-lived effects fade, potentially creating a longer-lasting high that makes the product seem higher quality. The effect is subtle enough that most users wouldn’t recognize it as a separate drug.
The health consequences are serious. Levamisole-contaminated cocaine is linked to dangerously low white blood cell counts, joint pain, and a distinctive pattern of purple skin lesions that can progress to tissue death. These skin wounds, caused by damage to small blood vessels, tend to appear on the ears, nose, and cheeks. In severe cases, the tissue damage requires surgical intervention.
Caffeine and Other Stimulants
Caffeine is one of the most widespread cocaine adulterants globally. Its bitter taste mimics cocaine, and research suggests caffeine actually amplifies some of cocaine’s stimulant effects when the two are taken together. It’s cheap, easy to source, and most people tolerate it well, making it an attractive option for anyone looking to stretch a supply without obvious side effects.
More concerning are amphetamines and synthetic cathinones (sometimes called “bath salts”) that occasionally appear in cocaine samples. These drugs target the same brain pathways as cocaine itself, boosting dopamine and other signaling chemicals. Compounds like mephedrone and methylone have been detected in cocaine supplies. Because amphetamines generally last much longer than cocaine, a user expecting a 30-minute high could find themselves wired for hours with no understanding of why. Behavioral research suggests these stimulants may be more reinforcing when combined with cocaine than either drug alone, increasing the risk of compulsive use.
Fentanyl: The Deadliest Contaminant
Fentanyl in cocaine is not a myth. A study analyzing samples from 25 U.S. states between 2021 and 2023 found fentanyl in roughly 15% of powder cocaine samples submitted to drug checking services. The contamination was not evenly distributed, with significant geographic variation. Notably, crack cocaine (the crystalline form) was far less likely to contain fentanyl: none of the 53 crack samples tested positive.
The DEA has reported that in some parts of the country, at least two-thirds of cocaine-related deaths also involve fatal levels of an opioid, usually fentanyl. This is particularly dangerous because cocaine users typically have no opioid tolerance. Even a tiny amount of fentanyl, invisible to the naked eye and undetectable by taste or smell, can stop breathing in someone whose body has never encountered a synthetic opioid.
Heroin has also been detected in about 7% of powder cocaine samples, adding another layer of unpredictable opioid exposure.
Xylazine and Emerging Contaminants
Xylazine, a veterinary sedative known on the street as “tranq,” has spread rapidly through the U.S. drug supply in recent years. It’s most commonly found mixed with fentanyl, but because fentanyl itself turns up in cocaine, xylazine can follow. It slows breathing, heart rate, and blood pressure to dangerous levels, and the critical difference from opioids is that naloxone (Narcan) does not reverse its effects.
Repeated xylazine exposure causes a distinctive pattern of painful skin wounds, open sores and abscesses that are difficult to treat and can appear even in people who smoke or snort rather than inject. In severe cases, the tissue damage can lead to amputation. Some users seek out xylazine intentionally for its sedative effects, but many encounter it unknowingly.
Other emerging contaminants include an industrial chemical called BTMPS, typically used in plastic manufacturing, which has recently been detected in drug samples from several U.S. regions. New synthetic opioids called nitazenes, some far more potent than fentanyl, have also begun appearing across North America. The drug supply is volatile, and the specific contaminants vary by location and shift over time.
Other Pharmaceutical Adulterants
Phenacetin, a painkiller banned in many countries, has been a recurring cocaine adulterant. Long-term phenacetin exposure is associated with kidney disease, increased cancer risk, and cardiovascular problems including hypertension. A 20-year study found that regular phenacetin users had over 16 times the risk of dying from kidney or urologic disease compared to non-users, and nearly three times the risk of dying from cardiovascular disease.
Hydroxyzine, an antihistamine with sedative properties, has also been found in cocaine. It crosses into the brain easily, producing drowsiness and anxiety relief that creates an unexpected contrast to cocaine’s stimulant effects. Paracetamol (acetaminophen) and diltiazem, a blood pressure medication, round out the list of commonly detected pharmaceutical additives.
How to Check for Fentanyl
Fentanyl test strips are inexpensive paper strips that can detect fentanyl in cocaine, methamphetamine, and other drugs. To use one, dissolve at least 10 milligrams of the substance in half a teaspoon of water, dip the wavy end of the strip for about 15 seconds, then lay it flat for two to five minutes. A single pink line means fentanyl was detected. Two pink lines mean it was not detected in that particular sample.
These strips have real limitations. They can’t tell you how much fentanyl is present, only whether it’s there. They may miss certain fentanyl analogs like carfentanil. And because fentanyl isn’t always evenly distributed through a batch, testing one portion doesn’t guarantee the rest is clean. They also don’t detect xylazine, levamisole, or any of the other adulterants described above. Still, given that fentanyl contamination is the most immediately lethal risk in the current cocaine supply, test strips provide a meaningful layer of information that can prevent a fatal exposure.