## Drugs Most Frequently Involved in Drug Overdose Deaths: United States, 2011–2016

The number of drug overdose deaths per year increased 54%, from 41,340 deaths in 2011 to 63,632 deaths in 2016 (Table A). From the literal text analysis, the percentage of drug overdose deaths mentioning at least one specific drug or substance increased from 73% of the deaths in 2011 to 85% of the deaths in 2016. The percentage of drug overdose deaths that mentioned only a drug class but not a specific drug or substance declined from 5.1% of deaths in 2011 to 2.5% in 2016. Review of the literal text for these deaths indicated that the deaths that mentioned only a drug class frequently involved either an opioid or an opiate (ranging from 54% in 2015 to 60% in 2016). The percentage of deaths that did not mention a specific drug or substance or a drug class declined from 22% of drug overdose deaths in 2011 to 13% in 2016.

#### Most frequently mentioned drugs

Table B shows the relative ranking of the top 15 drugs involved in drug overdose deaths for each year from 2011 through 2016 among deaths that mentioned at least one specific drug. The number of deaths for each drug should be interpreted in light of the improvements in reporting as described in Table A, and should be considered the minimum number for that drug because there could be additional deaths in which the drug was involved, but the drug was not reported in the literal text. The top 15 drugs were identified based on the number of drug overdose deaths per referent drug category. While the ranking changed from year to year, the top 10 drugs involved in overdose deaths remained consistent throughout the 6-year period. The top 10 drugs belonged to three drug classes:

• Opioids: fentanyl, heroin, hydrocodone, methadone, morphine, and oxycodone
• Benzodiazepines: alprazolam and diazepam
• Stimulants: cocaine and methamphetamine

The drugs that ranked 11–15 varied from year to year and included such drugs as diphenhydramine, citalopram, acetaminophen, carisoprodol, tramadol, oxymorphone, amitriptyline, clonazepam, gabapentin, and amphetamine.

For the top 15 drugs:

• Among drug overdose deaths that mentioned at least one specific drug, oxycodone ranked first in 2011, heroin from 2012 through 2015, and fentanyl in 2016.
• In 2011 and 2012, fentanyl was mentioned in approximately 1,600 drug overdose deaths each year, but mentions increased in 2013 (1,919 deaths), 2014 (4,223 deaths), 2015 (8,251 deaths), and 2016 (18,335 deaths). In 2016, 29% of all drug overdose deaths mentioned involvement of fentanyl.
• The number of drug overdose deaths involving heroin increased threefold, from 4,571 deaths or 11% of all drug overdose deaths in 2011 to 15,961 deaths or 25% of all drug overdose deaths in 2016.
• Throughout the study period, cocaine ranked second or third among the top 15 drugs. From 2014 through 2016, the number of drug overdose deaths involving cocaine nearly doubled from 5,892 to 11,316.
• The number of drug overdose deaths involving methamphetamine increased 3.6-fold, from 1,887 deaths in 2011 to 6,762 deaths in 2016.
• The number of drug overdose deaths involving methadone decreased from 4,545 deaths in 2011 to 3,493 deaths in 2016.

### Drug overdose deaths in 2016 involving multiple drugs

Table C shows the percentage of drug overdose deaths with concomitant involvement of other drugs for the top 10 drugs involved in drug overdose deaths in 2016. The percentage of deaths with concomitant involvement of other drugs varied by drug. For example, almost all drug overdose deaths involving alprazolam or diazepam (96%) mentioned involvement of other drugs. In contrast, 50% of the drug overdose deaths involving methamphetamine, and 69% of the drug overdose deaths involving fentanyl mentioned involvement of one or more other specific drugs.

## Discussion

### Findings for specific drugs

From 2011 through 2016, the number of drug overdose deaths increased by 54%, from 41,340 deaths in 2011 to 63,632 deaths in 2016. The most frequently mentioned drugs involved in these deaths were the opioids heroin, oxycodone, methadone, morphine, hydrocodone, and fentanyl; the benzodiazepines alprazolam and diazepam; and the stimulants cocaine and methamphetamine. Among drug overdose deaths that mentioned at least one specific drug, oxycodone ranked first in 2011, heroin ranked first from 2012 through 2015, and fentanyl ranked first in 2016. Cocaine ranked second or third throughout the study period. An analysis of trends among the most frequently mentioned drugs showed that, for several drugs, the age-adjusted rate of drug overdose deaths increased considerably within a relatively short period. From 2011 through 2016, the rate of drug overdose deaths involving heroin more than tripled, as did the rate of drug overdose deaths involving methamphetamine. The rate of drug overdose deaths involving fentanyl and fentanyl analogs doubled each year from 2013 through 2016, from 0.6 per 100,000 in 2013 to 1.3 in 2014, 2.6 in 2015, and 5.9 in 2016. Among the drugs discussed in this report, only methadone showed a decreasing drug overdose death rate, from 1.4 per 100,000 in 2011 to 1.1 in 2016

The 10 most frequently mentioned drugs were often found in combination with each other. Drug combinations often involved drugs of different drug classes. For example, the opioid fentanyl and the stimulant cocaine were mentioned concomitantly in nearly 4,600 deaths. The opioid oxycodone and the benzodiazepine alprazolam were mentioned concomitantly in more than 1,500 deaths. In some instances, the most frequently mentioned concomitant drug was in the same drug class as the referent drug. For example, the opioids fentanyl and heroin were both mentioned in approximately 5,900 deaths.

While the literal text can be used to identify the mention of the two drugs (fentanyl and heroin), the details to distinguish whether the heroin and fentanyl were taken as one (i.e., heroin laced with fentanyl) or as two separate drugs are often not available. The drugs most frequently mentioned in the literal text varied by the intent of the drug overdose death. In 2016, unintentional drug overdose deaths most frequently mentioned fentanyl, heroin, and cocaine, while suicides by drug overdose more frequently mentioned oxycodone, diphenhydramine, hydrocodone, and alprazolam.