Gabapentin’s Side Effect Risks

Pill bottle with gabapentin

For many people who take gabapentin, side effects such as sedation can be a challenge. Some effects, everything from severe swelling in extremities to mood swings, chronic exhaustion and hunger, have been described as “horrible” even though it was effective for neuropathy caused by cancer drugs.

David Cornblath, MD, professor of neurology at Johns Hopkins Hospital in Baltimore and a specialist in peripheral neuropathy, said the 3 main drugs approved for treating diabetic neuropathy — the most common type of neuropathy — “all have positives and negatives.”

He said the anti-seizure medication Neurontin (gabapentin) has the fewest side effects. Lyrica (pregabalin, another anti-seizure medication) comes next, and the antidepressant Cymbalta (duloxetine, a serotonin and norepinephrine reuptake inhibitor) has the most. (For more specifically on this topic, read: Treating Neuropathy)

Taking gabapentin (in any of its forms) as prescribed can depress the central nervous system, particularly if you have an underlying respiratory impairment or are a senior. In one medical trial it was shown that taking pregabalin alone increases pauses in breathing during sleep. Taking pregabalin alone or with an opioid pain reliever can depress breathing function dangerously.

Gabapentin is sometimes prescribed for back pain, but recent research has shown it to be ineffective.

A study published in 2014 in JAMA Internal Medicine found that adults with alcohol dependence that took gabapentin were more likely to be abstinent or refrain from heavy drinking compared to those on a placebo. Also, those on the active drug reported fewer cravings and less depression and insomnia.

Common side effects include drowsiness, tiredness or weakness, dizziness, headache, blurred vision, anxiety, memory problem, nausea, vomiting, heartburn, diarrhea and constipation. More serious side effects include rash, itching, swelling of the face, difficulty swallowing or breathing and seizures.

A new risk of suicidal behavior and overdose has been found among people who have prescriptions and are in their teens or early 20s. The study did not differentiate between those taking gabapentin as prescribed versus abuse, but all in the study had prescriptions for gabapentin. Head and body injuries and road traffic incidents were also higher among youths aged 15-24. Pregabalin (Lyraca, Lyrica CR and generics) was linked to the increase in harm, not all gabapentins.

Gabapentin is marketed as Neurontin (Pfizer) and Gralise (Assertio Therapeutics), as well as generics; gabapentin enacarbil, a prodrug of gabapentin marketed as Horizant (Arbor Pharmaceuticals); and pregabalin, marketed as Lyrica and Lyrica CR (Pfizer), as well as generics. (In this article, we are referring to any or all products listed as “gabapentin” unless otherwise indicated)

But an increasing number of opioid abusers use gabapentin for its side effect of sedation, reporting a calm feeling when combining gabapentin with opioids, muscle relaxants and anxiety medications. Some also experience an enhanced euphoria. But when overused or abused, it can cause significant organ or brain damage.

“Gabapentin was prescribed off-label for pain because it was thought to be a safer alternative to opioids,” said Steven Evans, MD, medical director of American Addiction Centers/Nevada. “But now people who don’t need it are starting to use it,” he said.

According to American Addiction Centers, rates of gabapentin misuse are 1.1% in the general population and 22% among those who abuse opioids. The most serious problems resulting from abuse are rash, itching, swelling of the face or mouth, hoarseness, difficulty swallowing or breathing and seizures.

At Solutions Recovery Treatment Center in Las Vegas, where gabapentin is used in addiction treatment, “In the last two years we’ve noticed a spike in clients losing medications and needing more refills,” said David Marlon, an addiction specialist and CEO of the center.

“It also happens in sober living communities and outpatient addiction treatment,” he said.

Gapantentin is approved in the US to treat epilepsy, fibromyalgia, neuropathic pain and post-herpetic nerualgia, but it is given off-label in addiction treatment and for migraine, hot flashes, restless leg syndrome, seizures, pain caused by shingles and more. It is the 7th-most prescribed drug in the United States. Pharmacy Times reported that 57 million prescriptions for gabapentin were written in the United States in 2015, a 42% increase since 2011.

“My radar was not on in terms of gabapentin being abused,” said Michele Matthews, associate professor of pharmacy practice at the Massachusetts College of Pharmacy and Health Sciences in Boston.

“With the shift from prescription opioids, there was an increase in non-opioid alternatives, and gabapentin was at the top of the list,” she said. “For the most part it wasn’t something we had to worry about. We’re seeing something different now.”

Matthews works with high-risk patients in the pain management clinic at Brigham and Women’s Hospital. She said that a typical dose for pain is between 1,800 and 3,600 mg a day.

“We’re starting to see requests for early refills,” Matthews said. “It’s similar to patients maybe misusing opioids. You can also tell if patients are difficult, [such as] yelling.”

“It reminds prescribers that medications need to be monitored closely,” she said.

Gabapentin is not scheduled as a controlled substance because when given alone it has not been considered addictive. When the drug is taken with other medications, gabapentin’s potential for abuse and addiction increases.

“Gabapentin has been linked with impaired driving and opioid use, highlighting the need to understand more fully its risk profile,” the authors of a 2017 study wrote in
the Journal of Addictive Behaviors

It doesn’t have the same risk of deadly overdose as opioids, but overdose can happen, and it carries the risk for significant organ or brain damage.

However, unlike opiates, there is no antidote for an overdose. Because of the drug’s long half-life — the amount of time in the body before it is half gone — immediate medical attention is necessary to manage the complications associated with a toxic amount of this drug,

The Charlestown Gazette-Mail reported that the number of fatal overdoses related to gabapentin in West Virginia jumped from 3 in 2010 to 109 in 2015. Between 2008 and 2011 the number of emergency room visits in metropolitan areas for misuse or abuse of gabapentin increased by nearly 5 times, according to the Drug Abuse Warning Network.

As with all medicines, gabapentin in its many forms can be helpful for some conditions. But it comes with side effects and risks that should be understood and considered before committing to using it.

Ronni Gordon

Ronni Gordon

Ronni Gordon is a Massachusetts-based freelance writer who got peripheral neuropathy 8 years ago after chemotherapy for leukemia. A former newspaper reporter, she has written for The New York Times, The Philadelphia Inquirer, Forbes and other publications.

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