Gabapentin is not classified as a high-risk controlled substance at the federal level, but it has drawn serious safety warnings from the FDA and increasing regulatory attention from individual states. The most significant alert came in December 2019, when the FDA warned that gabapentin and the related drug pregabalin can cause life-threatening breathing problems, especially when combined with opioids or other central nervous system depressants. That warning, combined with rising overdose deaths involving gabapentinoids and evidence of widespread misuse, has shifted how doctors, pharmacists, and regulators think about a drug once considered benign.
The 2019 FDA Breathing Warning
In December 2019, the FDA required new warnings on the labeling of gabapentin and pregabalin about the risk of serious breathing difficulties. The concern is respiratory depression, the same dangerous slowing of breathing that makes opioid overdoses fatal. The FDA issued this alert after reviewing cases of patients who experienced breathing problems while taking gabapentinoids, with the highest risk seen in people who were also using opioids, had lung disease such as COPD, or were elderly.1PubMed Central. Respiratory concerns of gabapentin and pregabalin: What does it mean to the pharmacovigilance systems in developing countries?
This was not a recall or a ban. The FDA’s action was a required labeling change, meaning that the drug’s prescribing information and patient medication guides had to be updated to reflect this risk. For someone taking gabapentin alone at a normal dose with no other risk factors, respiratory depression is rare. The danger escalates sharply when gabapentin is layered on top of other drugs that already suppress breathing.
Why Combining Gabapentin with Opioids Is Dangerous
The interaction between gabapentin and opioids is both pharmacological and mechanical, and understanding why it happens makes the FDA warning easier to appreciate. Opioids slow breathing on their own. Gabapentin, through mechanisms that are still being fully worked out, adds to that respiratory depression. But the danger goes beyond simply stacking two sedating drugs.
Gabapentin is absorbed through a specific transport system in the upper small intestine, and that system has a ceiling. At higher doses, the gut cannot absorb proportionally more drug, which is why doubling the dose does not double the blood level.2PubMed. A saturable transport mechanism in the intestinal absorption of gabapentin is the underlying cause of the lack of proportionality between increasing dose and drug levels in plasma Opioids, however, slow down the movement of food and drugs through the gut. When the intestines move more slowly, gabapentin spends more time in that narrow absorption window, and more of the drug gets into the bloodstream than would otherwise be expected.3PubMed Central. Gabapentin, opioids, and the risk of opioid-related death: A population-based nested case–control study So a person taking what seems like a normal gabapentin dose alongside an opioid may end up with much higher gabapentin levels than anticipated, on top of the additive respiratory suppression.
This pharmacokinetic wrinkle is one reason the combination is more dangerous than a simple “two sedatives together” story. The opioid essentially increases gabapentin’s own potency in ways that are hard to predict clinically.
Misuse, Abuse, and the “Gabapentin High”
For years, gabapentin was considered to have negligible abuse potential. It was not a controlled substance, it was not an opioid, and it was not a benzodiazepine. That perception has changed substantially. Systematic reviews now document that gabapentin misuse runs between roughly 15 and 22 percent in samples of people who already have opioid use problems, and that gabapentin abuse among those with a prescription ranges from 40 to 65 percent in those same high-risk groups.4PubMed Central. Gabapentin misuse, abuse, and diversion: A systematic review
People misusing gabapentin often report effects like euphoria, relaxation, and a sense of calm. The drug produces these effects on its own in some individuals, but is frequently taken alongside opioids or other substances to enhance or modify the high. Updated reviews confirm that opioid use disorder is the single greatest risk factor for gabapentinoid abuse, and that many people use gabapentin to self-medicate withdrawal symptoms, anxiety, or insomnia.5PubMed. Abuse and Misuse of Pregabalin and Gabapentin: A Systematic Review Update
An interesting pharmacological comparison helps explain the landscape. Pregabalin, gabapentin’s close relative, has faster onset, higher bioavailability, and nonsaturable absorption, which theoretically makes it easier to abuse. Yet gabapentin misuse rates in the United States are actually higher, largely because gabapentin has been far more widely prescribed and, until recently, far less regulated.6PubMed. Gabapentinoid Pharmacology in the Context of Emerging Misuse Liability Pregabalin has been a federal Schedule V controlled substance since 2005. Gabapentin still is not scheduled at the federal level.
Rising Overdose Deaths Involving Gabapentinoids
Overdose deaths in which gabapentinoids were detected have climbed steeply. Between 1999 and 2020, the rate of overdose deaths involving gabapentinoids rose from 0.06 per 100,000 to 1.51 per 100,000, reflecting about 16 percent annual growth over two decades. The increases accelerated toward the end of that period, with a 22 percent jump from 2018 to 2019 and a 32 percent jump from 2019 to 2020.7PubMed Central. Trends in Overdose Deaths involving Gabapentinoids and Z-Drugs in the United States
The critical detail is that these deaths were overwhelmingly driven by overdoses that also involved opioids. Gabapentin showing up on a toxicology report does not necessarily mean it was the sole cause of death, but it does mean it was part of a polydrug combination that proved fatal. This pattern reinforces the FDA’s 2019 warning and explains why the regulatory response has focused so heavily on the opioid-gabapentin overlap rather than gabapentin in isolation.
Who Faces the Greatest Risk
Gabapentin is not equally risky for everyone. Several populations face elevated danger, and the reasons differ by group.
People with Kidney Disease
Gabapentin is not broken down by the liver. It passes through the body unchanged and is eliminated entirely by the kidneys. When kidney function declines, gabapentin accumulates in the blood. A study of patients across different stages of kidney disease found that toxicity occurred exclusively in those with moderate or severe kidney impairment, and it was far more common and more severe in the worst-functioning group. Elderly patients with multiple health conditions were overrepresented among those who became toxic.8PubMed. Gabapentin toxicity in patients with chronic kidney disease: a preventable cause of morbidity This means that a dose considered safe in someone with normal kidneys can produce dangerously high drug levels in someone whose kidneys are not clearing it efficiently. Dose adjustment based on kidney function is essential, and this step is missed more often than it should be.9PubMed Central. Gabapentinoids: a therapeutic review
Older Adults
Age compounds the kidney issue, since kidney function naturally declines with age even in healthy people. But the risks for older adults extend beyond drug accumulation. Gabapentin causes dizziness, drowsiness, and impaired coordination, all of which increase fall risk. A study of older adults with cognitive impairment found that starting gabapentin was associated with roughly two and a half times the odds of a new fall.10PubMed Central. The Association of Gabapentin Initiation with Cognitive and Behavioral Changes in Older Adults with Cognitive Impairment: A Retrospective Cohort Study In elderly patients living in nursing homes, gabapentin’s saturable absorption pattern has been confirmed, and clearance correlates directly with estimated kidney filtration rate.11PubMed Central. Pharmacokinetics and Saturable Absorption of Gabapentin in Nursing Home Elderly Patients Falls in elderly people can lead to fractures, hospitalizations, and cascading health decline, making the fall-risk side effect clinically meaningful even if the drug is otherwise well-tolerated.
Pregnancy
Evidence on gabapentin in pregnancy is still evolving, but a large cohort study using U.S. Medicaid data found signals worth paying attention to. The overall rate of major malformations was not significantly higher in gabapentin-exposed pregnancies, but women who filled two or more gabapentin prescriptions had a roughly 40 percent higher risk of cardiac defects in their babies. Gabapentin exposure was also associated with higher risk of preterm birth, smaller-than-expected birth weight, and admission to the neonatal intensive care unit, with the strongest associations seen in women exposed both early and late in pregnancy.12PubMed Central. Gabapentin in pregnancy and the risk of adverse neonatal and maternal outcomes: A population-based cohort study nested in the US Medicaid Analytic eXtract dataset These are observational findings and cannot prove gabapentin caused the outcomes, but they are enough to warrant serious caution and a conversation with a prescriber about whether the benefits outweigh the risks during pregnancy.
Off-Label Prescribing and Weak Evidence for Common Uses
Part of the risk picture around gabapentin is not about the drug’s pharmacology but about how loosely it gets prescribed. Gabapentin is FDA-approved for epilepsy and postherpetic neuralgia (the nerve pain that lingers after shingles). But the majority of gabapentin prescriptions in the United States are written off-label, for conditions including chronic low back pain, generalized anxiety, insomnia, migraines, and fibromyalgia. Much of this prescribing surged as clinicians looked for alternatives to opioids for pain management.13PubMed Central. A Cohort Study of New Off-label Gabapentin Prescribing in Chronic Opioid Users
The problem is that the evidence for many of these off-label uses is thin. Chronic low back pain is one of the most common reasons gabapentin gets prescribed, yet the trial evidence is discouraging. A randomized controlled trial found that patients on gabapentin and those on placebo both reported about a 30 percent reduction in pain, with no significant difference between the groups. The researchers concluded gabapentin appeared ineffective for chronic low back pain with or without a radiating component.14PubMed Central. A randomized controlled trial of gabapentin for chronic low back pain with and without a radiating component A systematic review and meta-analysis of gabapentinoid trials for chronic low back pain found minimal pain improvement compared to placebo and rated the overall quality of evidence as very low.15PLOS Medicine. Benefits and safety of gabapentinoids in chronic low back pain: A systematic review and meta-analysis of randomized controlled trials
For psychiatric uses, the picture is mixed. A systematic review found that gabapentin may help with certain anxiety disorders and shows clearer efficacy for alcohol craving and withdrawal symptoms, but evidence was lacking for depression, PTSD prevention, OCD, and most other psychiatric conditions.16PubMed Central. Gabapentin Therapy in Psychiatric Disorders: A Systematic Review Single-site studies suggest potential benefit for alcohol use disorder, with reductions in drinking and improvements in alcohol-related sleep disturbance.17PubMed Central. Gabapentin for the treatment of alcohol use disorder But “single-site studies lend support” is a long way from robust, replicated evidence.
The irony of off-label prescribing in chronic opioid users is worth noting. In a cohort of over 172,000 patients already on opioids, a new gabapentin prescription was associated with a decrease in opioid dosage in about 39 percent of patients, no change in 14 percent, and an actual increase in opioid dosage in 47 percent.13PubMed Central. A Cohort Study of New Off-label Gabapentin Prescribing in Chronic Opioid Users The goal of adding gabapentin is often to reduce opioid use, but in nearly half of patients, that is not what happened. Meanwhile, combining the two drugs increases the respiratory risk discussed earlier.
Withdrawal and the Importance of Tapering
Gabapentin can produce physical dependence, and stopping abruptly after prolonged use can trigger withdrawal. Symptoms range from anxiety, insomnia, nausea, and sweating to more serious manifestations. A documented case report described a patient who, even with a gradual taper, developed respiratory symptoms within a day of stopping gabapentin, followed by worsening over the next ten days, culminating in severe mental status changes, chest pain, and high blood pressure.18PubMed. Gabapentin withdrawal syndrome in the presence of a taper
Withdrawal does not happen to everyone, and it tends to be more pronounced in people who have been on higher doses for longer periods. But the fact that it can occur even during a taper underscores that gabapentin should never be stopped cold turkey without medical guidance. If you are on gabapentin and want to stop, talk to your prescriber about a gradual dose reduction.
How States Are Responding
Because gabapentin is not a federally scheduled controlled substance, states have taken matters into their own hands. As of the mid-2020s, a growing number of states have either classified gabapentin as a Schedule V controlled substance (the lowest scheduling tier, shared by drugs like cough syrups with small amounts of codeine) or added it to their prescription drug monitoring programs (PDMPs), the databases that track controlled substance prescriptions to flag potential misuse.
These approaches work differently and produce different results. States that classified gabapentin as Schedule V saw larger reductions in prescribing. One study of Medicare enrollees found that Schedule V classification reduced total days of gabapentin prescribed by about eight days per enrollee, while PDMP-only monitoring produced a reduction of about one day per enrollee.19PubMed Central. Association of State-Imposed Restrictions on Gabapentin with Changes in Prescribing in Medicare In Kentucky and West Virginia, which both adopted Schedule V classification, gabapentin prescription fills among Medicaid enrollees dropped significantly and sustainably compared to a control state without such regulation.20PubMed Central. Decreased Gabapentin Prescription Fills Among Medicaid Enrollees Following State-Level Schedule V Controlled Substance Classification in Kentucky and West Virginia
The United States and Puerto Rico have some of the highest gabapentinoid consumption rates in the world, and gabapentin accounts for the bulk of that use, in part because pregabalin’s federal scheduling since 2005 created barriers that did not exist for gabapentin. Countries with different regulatory approaches show different prescribing patterns: in Australia, pregabalin dominates, while in New Zealand, where pregabalin was not publicly funded until 2017, gabapentin grew instead. The UK reclassified all gabapentinoids as Schedule 3 controlled drugs in 2019.21Nature Communications. Gabapentinoid consumption in 65 countries and regions from 2008 to 2018: a longitudinal trend study These international comparisons suggest that scheduling decisions have a meaningful, if imperfect, effect on how widely the drugs are used.
Gabapentin Use in People Being Treated for Opioid Addiction
One of the more complicated prescribing situations involves gabapentin and buprenorphine, the medication widely used to treat opioid use disorder. Gabapentin is frequently co-prescribed with buprenorphine, often for legitimate reasons: many patients entering addiction treatment also have neuropathic pain, anxiety, or mood disorders for which gabapentin has at least some evidence of benefit. A study of patients starting buprenorphine found that gabapentin was more likely to be prescribed to women, people over 30, and those with co-occurring mood disorders, anxiety, or neuropathic pain.22JAMA Psychiatry. Gabapentin Use Among Individuals Initiating Buprenorphine Treatment for Opioid Use Disorder
The tension is clear. These patients have legitimate conditions that gabapentin might help, but they are also among the highest-risk group for gabapentin misuse. Having a sedative use disorder was one of the strongest predictors of receiving gabapentin in this population. Whether the prescribing in these cases reflects careful clinical judgment or a pattern that inadvertently enables misuse is an open question that the data alone cannot fully resolve. The finding that gabapentin was significantly less likely to be prescribed to Black or Hispanic patients adds another layer of complexity, suggesting that access and prescribing patterns are shaped by factors beyond clinical need alone.
How Gabapentin Actually Works in the Brain
Gabapentin’s mechanism is often described loosely as “calming nerve activity,” but its pharmacology is unusual compared to most drugs that affect the nervous system. It was designed to mimic the neurotransmitter GABA, and its name reflects that intention, but it does not actually bind to GABA receptors or directly affect GABA activity. Instead, gabapentin binds to a specific subunit of voltage-gated calcium channels in nerve cells. This binding does not immediately block calcium flow in any dramatic way. Rather, it appears to work by disrupting the trafficking of those calcium channel subunits to the cell surface over time, gradually reducing the release of excitatory neurotransmitters.23PubMed Central. Pharmacological disruption of calcium channel trafficking by the alpha2delta ligand gabapentin
This slow mechanism helps explain both gabapentin’s therapeutic delay (it often takes days to weeks to reach full effect) and why its abuse profile differs from faster-acting sedatives. It also explains something clinicians observe: gabapentin does not reliably produce the immediate euphoria that drives classic addiction cycles, yet it clearly produces rewarding effects in some people, especially at high doses or when combined with other substances. The gap between its relatively mild pharmacology in isolation and its real-world involvement in overdose deaths and misuse is one of the reasons the drug caught regulators off guard for so long.
Careful patient selection matters. A UK primary care study emphasized the need to educate prescribers about the risks of gabapentinoids, particularly when combined with other central nervous system depressants, and to weigh those risks more carefully before writing a prescription.24PubMed Central. Risk of adverse outcomes during gabapentinoid therapy and factors associated with increased risk in UK primary care using the clinical practice research datalink: a cohort study For many patients using gabapentin appropriately for an FDA-approved condition at a proper dose, the drug remains a useful tool. The risk profile changes substantially when the dose is high, kidney function is impaired, other sedating drugs are on board, or the condition being treated has weak evidence of responding to gabapentin in the first place.