Gabapentin Prescribing Rises in Addiction Treatment Despite Weak Evidence

Doctors are prescribing the nerve pain medication gabapentin to a growing share of patients in addiction treatment, even though the evidence supporting that practice remains thin—and patients taking the drug without a prescription still outnumber those with one nearly two to one. The findings come from a large analysis of urine drug tests from 2,053 substance use treatment facilities across all 50 states, published in the journal Drug and Alcohol Dependence.

Gabapentin is approved by the Food and Drug Administration for partial seizures and certain types of nerve pain. In addiction treatment settings, clinicians frequently turn to it off-label to ease withdrawal symptoms and to manage co-occurring anxiety, insomnia, and chronic pain. Yet clinical trials have shown no benefit for cocaine or methamphetamine use disorders, and the broader literature on its effectiveness in substance use treatment remains sparse.

Prescribed and unprescribed use move in opposite directions

The research team, led by psychiatry researcher Matthew S. Ellis of Washington University in St. Louis with co-authors Penn Whitley and Steven D. Passik of the testing laboratory Millennium Health, found that 5.9 percent of adult patients in the sample had a documented gabapentin prescription. Prescribing increased across every category of substance use disorder over the study period, climbing highest among patients with sedative use disorders. Adults aged 55 and older, women, and patients with anxiety, mood disorders, insomnia, or pain were the most likely to receive the medication.

Unprescribed use told a different story. Researchers detected gabapentin in 11.3 percent of patients who had no prescription for it—nearly double the prescribed rate—though that figure appears to be slowly declining. People using gabapentin outside a prescription were more likely to test positive for every other drug class analyzed. Cannabis was the most frequently detected substance in both groups, but the fentanyl finding stood out: among patients using gabapentin without a prescription, fentanyl detection rose from 12 percent to 29 percent during the study period.

The authors caution that the data cannot show whether addiction specialists are writing the prescriptions or whether patients arrive with gabapentin from outside providers for unrelated conditions. Some nonmedical use may also be unintentional, since the drug can appear as an adulterant in the illicit supply.

What this means for treatment

The pattern places clinicians in a difficult position. Patients taking gabapentin without a prescription often report self-medicating for pain, sleep problems, or withdrawal—the same symptoms the drug is prescribed to address—yet unprescribed use clusters with riskier drug involvement, including rising fentanyl exposure. For people in opioid addiction treatment, that overlap complicates both screening and care planning.

The study adds to a growing body of research suggesting that prescription medications with modest abuse potential can become entangled in the overdose crisis when they circulate outside medical supervision. The researchers note that monitoring both prescribed and unprescribed gabapentin use may help treatment programs identify patients at elevated risk—particularly as fentanyl continues to appear alongside it in toxicology results.