Opioids: What are these drugs and why are they dangerous

Opioids are a class of drug that have been used for pain relief for centuries. Opioids include multiple types of medications available by prescription, as well as illicitly produced or distributed drugs, such as heroin, fentanyl, or “look-alike” opioid pills. Opioids can be safe and effective for certain types of pain when prescribed and monitored carefully; however, they also come with potential risks, such as the development of physical tolerance (needing higher doses to achieve the same pain relief) and the development of opioid use disorder. Opioid use disorder is an illness characterized by continued use of opioids despite negative effects on health and functioning. This can be a devastating and chronic illness; however, effective treatment is available.

Heroin is an opioid derived from morphine. Heroin is typically available in powdered form and may vary in color, usually appearing to be white or brown, but it also can take the form of a hard, sticky substance known as “black tar” heroin. Powdered heroin may be ingested by inhaling it (through the nose, i.e., “snorting”), smoking it, or injecting it into a muscle or a vein. This latter process requires boiling the powdered heroin into a liquid to draw into a syringe to inject.

Fentanyl is a synthetic opioid that can be 50 to 100 times stronger than morphine. Fentanyl can be prescribed by a doctor to treat pain but has increasingly become available for illegal purchase, often either mixed with heroin or as a substitute for heroin. The presence of fentanyl, either alone or mixed with other substances such as heroin or cocaine, can dramatically increase the risk for overdose because of its potency. The increased availability of fentanyl (and similar synthetic opioids) has been a major driver of the rapid increase in overdose deaths since 2013 (“Understanding the opioid overdose epidemic,” 2024). Other highly potent synthetic opioids, such as carfentanil (roughly 10,000 times more powerful than morphine), have also been found in some regions of the United States.

Heroin has long been thought of as a risky drug, serving as a barrier to wide-scale use. However, prescription opioids are seen as much less risky, which has lowered the bar for initiating opioid use. In recent years, fatalities have dramatically spiked, largely because of the increased availability of highly potent synthetic opioids (such as fentanyl and carfentanil) spreading through the drug supply (“Drug overdose deaths: Facts and figures,” 2024). These highly potent opioids may be substituted into illicit drugs sold as powder heroin and are also being “pressed” into illicitly sold pills that look similar to pills sold by a pharmacy (but are far stronger).

Prescription opioids, such as oxycodone, are sold in a variety of formulations (e.g., combined with aspirin or acetaminophen and in immediate or slow-release pills). These pills may be swallowed or crushed into a powder to be snorted or prepared for injection. Most people who misuse prescription opioids obtain them from friends or family members, although people may also obtain them from a doctor or buy them illegally (Richesson et al., 2024). Illegally manufactured opioid pills may be mixed with other substances, including fentanyl, even if they are indistinguishable from those purchased at a pharmacy. These pills are highly dangerous and can lead to overdose, particularly when the dose of opioid received far exceeds what is expected by the person consuming it.

Given the multiple formulations and illegal manufacturing of prescription opioids, unidentified pills can raise concerns. The internet provides a number of resources for identifying what a pill might be. For example, WebMD provides a tool called the Pill Identifieropens in new window that offers three features to help people identify a drug from the pill design: the numerical or letter imprint information, the color of the pill, and the shape of the pill. However, this will not help to identify “look-alike” pills that contain fentanyl. Only pills obtained directly from a pharmacy can be confidently identified.