Imagine taking a medication like acetaminophen—but with no standardization or quality control. One pill could contain 10% of a dose; another could contain 1,000%. Taking a pill might treat your headache, it might do nothing, or it might cause liver failure. A person who uses drugs from the street market faces this dilemma every day. Substances sold as heroin could contain fentanyl, which is far stronger and more likely to cause an overdose; a dose of “MDMA” may actually contain methamphetamine. Even people selling substances are unlikely to know what may have adulterated, contaminated, or been cut into the supply they’re selling. Without knowledge of what is in their supply, people who use drugs experience heightened risk of unintentional overdose and injury.

Drug checking puts knowledge into the hands of people who use substances. While at-home testing for substances like fentanyl is possible through the use of test strips, harm reduction organizations that provide drug checking services typically use infrared spectroscopy to analyze substances and determine their chemical makeup. The equipment used for testing only requires 1-2 milligrams to determine the chemical makeup of a substance. A person may bring substances they haven’t used yet to inform their decision on whether and how much to use, or they could bring a small amount of a substance that they had an adverse reaction to in order to determine what caused it. These programs are evidence-based responses to overdose that respect autonomy and ensure people have the information they need to reduce their risk.

Drug checking also has significant public health benefits. Drug checking organizations use the information gleaned from testing substances to release public announcements on trends in the drug supply, like the presence of new emerging substances. In California, organizations providing on-the-ground drug checking services were among the first to sound the alarm on xylazine in the drug supply, providing both public health officials and people who use drugs with valuable information to prevent overdose. While law enforcement often pushes strategies like wastewater testing, these methods do not inform individuals of their risk, infringe on people’s privacy by testing their waste without their consent, and often fail to trigger alerts for new emerging substances and those that are not eliminated via human waste.

Drug checking is a harm reduction strategy that offers benefits to both individual and public health. Bills like AB 2136 (Jones-Sawyer), which was signed into law in 2024, ensure that these programs can continue to provide high-quality information to people who use substances without fear of arrest or penalties. By supporting and funding drug checking, we can give people who use drugs the information they need to make informed decisions and protect themselves.