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Gabapentin Uses, Dosage & Side Effects

Written by Puya Yazdi, MD | Last updated:
Evguenia Alechine
Jonathan Ritter
Medically reviewed by
Evguenia Alechine, PhD (Biochemistry), Jonathan Ritter, PharmD, PhD (Pharmacology) | Written by Puya Yazdi, MD | Last updated:

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Pills and drink

Gabapentin is a drug used to treat partial seizures, pain from nerve damage, and some movement disorders. However, many people misuse or abuse it, which can be extremely dangerous. Read this post to learn about the conventional uses of gabapentin and the risks associated with gabapentin abuse.

Disclaimer: Gabapentin is available only with a doctor’s prescription. By writing this post, we are not recommending this drug. Please discuss your medications with your doctor.

What is Gabapentin?

Gabapentin is an anticonvulsant/antiepileptic drug usually prescribed under the brand name Neurontin.This drug cannot cure epilepsy. It will help control seizures for as long as a person continues to take it.

It is used to treat partial seizures and postherpetic neuralgia (pain that occurs after shingles). Some doctors also prescribe it for neuropathic pain and essential tremors. It is not used to treat minor pain.

Therefore, gabapentin is approved and indicated for managing [1]:

  • Postherpetic neuralgia in adults
  • Partial onset seizures in adults and pediatric patients 3 years and older with epilepsy, as part of adjunctive therapy

However, it has several controversial “off-label” uses with mixed results.

Gabapentin is similar to GABA but is structurally and functionally different (structural analog). Importantly, gabapentin can cross the blood-brain barrier, while GABA cannot [2].

Mechanism of Action

The mechanisms are not fully understood, but it is known that gabapentin increases GABA in the brain in both rodent and human brains [3].

Gabapentin increases the activity of the enzyme glutamate decarboxylase (GAD), which converts the neurotransmitter glutamate into GABA [4].

Gabapentin is able to cross the blood-brain barrier and reach the brain through the amino acid transporter LAT1 (SLC7A5), which also carries neurotransmitters such as glutamate [5, 6].

Gabapentin binds to calcium ion channels in the brain and spine, which decreases neurotransmitters like glutamate, calcitonin gene-related peptide (CGRP), and substance P. This reduces abnormal brain activity that causes seizures, tremors, and pain [7, 8, 9].

Uses of Gabapentin

1) Seizures in Drug-Resistant Partial Epilepsy

Many epileptic patients suffer from drug-resistant epilepsy and require additional intervention to control their seizures [10].

Gabapentin is primarily used as an add-on medication for partial epilepsy, also known as focal epilepsy. In focal epilepsy, the seizures start on one side of the brain, while in generalized epilepsy seizures start on both sides [11, 2, 12].

Gabapentin can reduce the frequency of both drug-resistant secondarily generalized partial seizures and complex partial seizures [2].

A meta-analysis of 1,206 patients with drug-resistant partial epilepsy showed that gabapentin significantly reduces seizure frequency [11].

In animal studies, gabapentin protected rat brains from multiple seizure-causing toxins (for example kainic acid), in addition to those caused by electroshock or sounds [2, 13].

2) Pain

Neuropathic pain is any pain due to nerve damage. Gabapentin reduces neuropathic pain caused by shingles (postherpetic neuralgia) and diabetes (peripheral diabetic neuropathy) [14].

Gabapentin may also be effective for other pain-related diseases such as multiple sclerosis, fibromyalgia, and sciatica. However, this is considered off-label use [14, 15, 16].

Specifically, gabapentin reduces pain caused by increased sensitivity to already painful stimuli (hyperalgesia) and pain due to normally painless stimuli (allodynia), by binding to calcium channels [14].

A meta-analysis of 5914 patients with chronic neuropathic pain found that 30-40% of them (on a normal daily dose of gabapentin – 1800 – 3600 mg) experienced “worthwhile” pain reduction by at least 50%. “Worthwhile” pain reduction is associated with improved [15]:

  • Sleep disturbances
  • Fatigue
  • Depression
  • Quality of life
  • Quality of work
  • Quality of function

However, not everyone will experience this level of improvement and may find that the side effects (dizziness, sleepiness, swelling of limbs, and gait disturbance) outweigh the benefits [15].

A study of 351 patients focused on patients with at least two of the following [17]:

  • Pain due to normally painless stimuli (allodynia)
  • Burning pain
  • Shooting pain
  • Increased sensitivity to pain (hyperalgesia)

Overall, gabapentin significantly improved their neuropathic pain and quality of life [17].

Similarly, there is some evidence that gabapentin treats sciatica, which is pain that spreads from the back to below the knee. It has multiple causes (i.e. herniated disk, tumors, infections, pregnancy, etc.). Two case studies showed that gabapentin significantly improved pain, and one patient was pain-free [16].

Pain and Impaired Walking due to Multiple Sclerosis

Multiple sclerosis is a common autoimmune disease of the brain. Four out of five multiple sclerosis patients suffering from spasticity, which involves contraction of the muscles that can impair walking and cause pain [18].

Gabapentin reduced spasticity caused by multiple sclerosis in both doses of 300 mg/day and 900 mg/day in two studies [19, 20].

Cancer Pain

Gabapentin, in combination with opioids (morphine), improves neuropathic cancer pain, leading to more daily activity, better sleep, improved mood, and enhanced quality of life. Studies indicate that when gabapentin and morphine are used together, they can be prescribed at lower doses [21].

Fibromyalgia

Gabapentin may also be used off-label to treat pain due to fibromyalgia, which affects approximately 2% of the population [22].

Fibromyalgia is pain that lasts more than three months [23].

A study of 150 patients found that gabapentin significantly improved pain and sleep. Notably, half of the patients experienced at least a 30% reduction in their pain [24].

3) Essential Tremor and Restless Leg Syndrome

Essential Tremor

Essential tremor is a movement disorder that causes tremors when trying to continue a particular action [25].

Gabapentin significantly improved tremors in a study of 16 patients who were not taking other tremor medications. However, additional large-scale studies are needed to determine its efficacy in such cases [26].

Other studies showed that gabapentin as an add-on medication has little to no effect on essential tremor [27, 25].

Scientists believe gabapentin may improve tremor through binding and inhibiting calcium-ion channels (alpha-2 delta subunit) leading to a reduction in tremors. This has not been confirmed [8].

Restless Leg Syndrome

Restless leg syndrome is a brain disorder that also results in involuntary movements. A study of end-stage kidney failure patients found that gabapentin (usually 200 – 300 mg/3 times a week) reduced symptoms of this syndrome in combination with dialysis [28].

A small trial with 8 patients suggests that regular use of gabapentin may:

  • Decrease limb movement
  • Decrease pain
  • Decrease sensory and motor symptoms
  • Improve sleep quality [29]

However, no conclusions can be drawn from such a small, potentially-biased study. Large clinical trials are needed to determine the effectiveness of gabapentin in people with restless leg syndrome.

4) Anxiety

Several small studies indicate that gabapentin shows potential for improving anxiety. However, the current evidence does not support the use of gabapentin for anxiety due to the lack of proper clinical data.

A study of 50 female patients with moderate-to-high anxiety found that taking 1,200 mg of gabapentin before surgery significantly reduced anxiety and pain catastrophizing, which is when patients are severely fixated and worried about experiencing or anticipating pain [30].

Social anxiety causes people to fear and avoid social situations. A small study of 8 patients with social anxiety disorder found that gabapentin (1,800 mg/day) reduces anxiety similarly to other anxiety medications like selective serotonin reuptake inhibitors (SSRIs) and benzodiazepines [31].

Finally, gabapentin also reduced anxiety and improved sleep in patients with both an anxiety-related disorder (i.e., panic disorder, alcohol dependence, obsessive-compulsive disorder, generalized anxiety, or drug dependency) and schizophrenia, schizoaffective or bipolar disorder. However, these data come from an old, low-quality study and are unreliable [32].

5) Migraines

Gabapentin is also used off-label to treat chronic migraines. Existing evidence does not support this use.

A study of 143 patients found that gabapentin helps treat chronic migraines, and almost half of the patients taking 2,400 mg/day had their migraine frequency cut in half [33].

Another study of 63 patients showed similar results while taking 1200 mg/day [34].

Limited evidence suggests that gabapentin may be effective in treating chronic migraines and chronic or high-altitude headaches. Large-scale studies are needed [35].

In rats, gabapentin reduces the release of calcitonin gene-related peptide (CGRP) and substance P in the spinal cord, which is associated with inflammation and pain [35].

5) Sleep

Hot flashes are a common side effect in breast cancer survivors and women in menopause and can negatively impact sleep quality.

A study of 58 breast cancer survivors with chronic daily hot flashes found that a daily dose of gabapentin (900 mg) improves the duration and quality of their sleep [36].

In another small study, gabapentin improved hot flashes due to menopause [37].

However, the above studies had small sample sizes and were limited to one location. Large-scale, multi-center trials are needed to explore whether gabapentin improves sleep in breast cancer survivors and women experiencing symptoms of menopause.

6) Opioid Withdrawal and Addiction

For opioid addiction, a study of 27 patients suggested that taking high doses of gabapentin (1,600 mg) in combination with methadone may reduce some opioid withdrawal symptoms such as coldness, twisting (yawing), diarrhea, mood deterioration (dysphoria), and muscle tension [38].

A similar study of 60 patients showed similar opioid withdrawal symptom relief, but only at 300 mg. Gabapentin also lowered the amount of methadone that the patients used [39].

Recent studies suggest gabapentin may also play a role in the off-label treatment of alcohol and nicotine addiction, though the evidence is extremely limited and inconclusive [40].

Dosage

The typical adult dosage (> 12 years) is between 900 – 3,600 mg/day, depending on the indication and individual response [9, 1].

Doctors will typically gradually titrate the dosage, starting at lower doses and titrating up to a full dose.

The drug is normally taken 3 times per day due to its short half-life [14].

Epilepsy

Adults (over 12 years): The recommended maintenance dose is 900-1,800 mg/day (maximum 2,400 mg/day)

  • Titration: Should be started at 300 mg/day (1 x 300 mg), then titrated up to 600 mg/day (2 x 300 mg) and finally to 900 mg/day (3 x 300 mg); the dosage is increased as needed
  • Maximum dose: 2,400 mg (3 x 800 mg/day)

Children (3-4 years): 40 mg/kg/day (divided into three doses)

Children (5-12 years): 25 – 35 mg/kg/day (divided into three doses) [41]

Postherpetic Neuralgia

Adults (over 12 years): Effective dose is 900 – 1,800 mg/day [41]

  • Day 1: 300 mg (1 x 300 mg/day)
  • Day 2: 600 mg (2 x 300 mg/day)
  • Day 3: 900 mg (3 x 300 mg/day)
  • Increased as needed

Note: People with kidney problems are usually prescribed lower doses [41].

100 mg capsules are the lowest dose available. They may be prescribed for those who require lower doses (i.e., children and people with kidney problems) or in combination with other capsules and tablets.

300 mg capsules are used as the initial dose for the treatment of epilepsy and postherpetic neuralgia in adults. Patients are started at 1 x 300 mg/day and the dosage is increased by 300 mg increments until an effective dose is reached [41].

800 mg tablets are the highest dose available. In the treatment of epilepsy, the maximum recommended dose is 2,400 mg/day (3 x 800 mg/day) [41].

In India, over 80% of doctors only prescribe 100 mg – 300 mg of gabapentin per day for the treatment of neuropathic pain. Insufficient evidence supports this practice [42].

Side Effects and Safety

The following side effects have been reported:

  • Sleepiness [2, 33]
  • Dizziness [2, 33]
  • Poor coordination or unsteady gait (ataxia) [2]
  • Weakness/Fatigue [2, 33]
  • Nausea [43]
  • Weight gain [43]
  • Infections [33]
  • Swelling (edema) [15]
  • Memory loss [44]
  • Diarrhea [44]
  • Suicidal behavior and ideation [1]

Animal studies have shown that gabapentin may negatively affect pregnancy. Human data are lacking. Consult your doctor to discuss the medications you are taking if you are pregnant or trying to conceive [45, 46].

Gabapentin passes through the kidneys and is released from the body with the urine. Gabapentin poses a risk for patients with kidney problems. However, it can be used with guidance from a doctor and in conjunction with dialysis, which will remove the gabapentin from the body [47].

Abuse

As the opioid crisis continues, there has been a notable increase in gabapentin prescription and abuse. A primary reason for gabapentin misuse is to “get high” [48, 49].

Gabapentin abuse is extremely dangerous. Most people who abuse gabapentin have a history of drug abuse. Never use gabapentin without a doctor’s prescription. Talk to your doctor about any past drug abuse problems you may have had [1, 49].

Some users report a “high” when taking gabapentin alone or in combination with other drugs. Self-described effects include:

  • Euphoria (like a weaker opioid high)
  • Marijuana-like high
  • Relaxation/Calm/Sedation
  • Effects similar to amphetamine

Gabapentin (1,500 mg – 12,000 mg) may cause euphoria alone or when combined with:

  • Alcohol
  • Baclofen
  • Buprenorphine/naloxone
  • Methadone
  • Quetiapine

Gabapentin (600 mg – 4,800 mg) may cause sedation alone or when combined with:

  • Quetiapine
  • Alcohol
  • Marijuana
  • Buprenorphine/naloxone [50]

Gabapentin abuse can lead to serious side effects, toxicity, and death [49].

Withdrawal

Do not stop using gabapentin without seeing your doctor. Stopping this medication suddenly may cause seizures. Your doctor may need to gradually reduce the amount you are taking before stopping it completely.

Abruptly stopping gabapentin can increase the risk of anxiety, insomnia, and nausea [51].

Withdrawal symptoms can appear in the window of 12 hours to a week after stopping the medication. Most occur within a 48-hour window [52].

Symptoms usually include agitation, confusion or disorientation. However, they may also consist of sweating, gastrointestinal problems, tremor, irregular heartbeat, high blood pressure, sleep problems, restlessness, immobility (catatonia), and seizures. Gabapentin uses during pregnancy may cause withdrawal in newborns [52].

Overdose

Gabapentin is hardly metabolized, so gabapentin overdose is rare. However, in people with kidney problems, toxicity is possible and symptoms may include: dizziness, confusion, lack of energy (lethargy), twitching (myoclonus), poor coordination or unsteady gait (ataxia), and shaking (tremulousness). Peritoneal dialysis effectively treats toxicity [53].

Importantly, gabapentin may increase the chance of drug overdose when used in combination with opioids [50, 54].

Effects on Depression and Suicide

An analysis of 131,178 psychiatric and nonpsychiatric patients found that gabapentin was associated with decreased suicides among psychiatric patients or it no association was found [55].

However, another analysis of 297,620 patients found that gabapentin was associated with an increased risk of suicide or suicide attempts [56].

Drug Interactions

  • Antacids – Antacids (magnesium oxide or aluminum) decrease the effect of gabapentin on the body [57, 58]. Take gabapentin at least two hours apart from antacids [14].
  • Opioids [50] – There is a risk of drug abuse among opioid addicts. Gabapentin may affect breathing, increasing the risk of opioid overdose and death [50, 54].

Gabapentin and Alcohol

  • In addition to the risk of abuse, gabapentin may increase the effects of alcohol, including impairing coordination dexterity function [50]. Combining gabapentin with alcohol is dangerous [50, 54].

Scientists are investigating whether gabapentin has potential for worsening dependence, though no conclusions can be drawn from the existing evidence. An animal study found that gabapentin (60 mg/kg) increased rats’ dependence on alcohol. There is an interest in determining whether Gabapentin poses the same risk to humans, i.e., social drinkers [59].

Gabapentin FAQ

Is Gabapentin a Narcotic?

In the US, gabapentin is not officially classified as a narcotic. The FDA defines a narcotic as any of the following:

  • Opium/Opiates and their derivatives (e.g. heroin and morphine)
  • Poppy straw
  • Coca leaves and extracts with their derivatives intact (cocaine and ecgonine)
  • Cocaine and its derivatives, salts, and/or isomers
  • Ecgonine and its derivatives, salts, and/or isomers
  • Any combination of the above [60]

Informally, however, the definition is broader and may refer to any addictive, controlled, or illegal painkiller that affects mood and behavior.

Medically, it has the same meaning as opioid medications but often gives a negative connotation [61].

In the US, gabapentin is a prescription medication that is not listed under the Controlled Substances Act. However, gabapentin is misused and illegally sold as a street drug [48, 49].

Gabapentin is often abused in combination with, or instead of, opioids, which are narcotics. This can cause toxicity and death [48].

Is Gabapentin Addictive?

Gabapentin abuse is on the rise. It’s estimated that 1% of people misuse gabapentin, though some estimates indicate more widespread abuse [52, 50, 49].

People abuse gabapentin at 3 – 20 times the recommended dose, which is extremely concerning and increases the risk of serious side effects and even death [62].

According to one study, around 50% of the people misuse the prescribed medication as self-medication, recreational use, or self-harm. Some people combine it with opioids, benzodiazepines, alcohol, or heroin [50, 54].

Opioid addicts/abusers are most at risk. About 1 in 5 opioid abusers abuse gabapentin [50].

Combining gabapentin with opioids can increase the chances of overdose and death due to respiratory problems. This may be due to gabapentin reversing the person’s accumulated drug tolerance or due to its effect on breathing [54].

Although most cases of gabapentin addiction have been found in patients with histories of drug (opiate and cocaine) or alcohol abuse, people with no history may also be at risk [63].

Is Pregabalin a Good Alternative to Gabapentin?

Pregabalin is a drug in the same class as gabapentin (gabapentinoids), with a similar mechanism of binding to calcium channels [64].

Pregabalin is absorbed much more quickly than gabapentin.

Dosages for pregabalin are much lower than gabapentin, ranging from 75 – 600 mg/day.

Gabapentin and pregabalin are absorbed in the small intestine, but pregabalin is also absorbed by the colon [64].

Pregabalin is taken two or three times a day while gabapentin is usually taken three times a day. Additionally, pregabalin differs from gabapentin in that its absorption into the body is independent of the dose. However, gabapentin is dose-dependent, meaning that as the dose increases, the proportion of gabapentin absorbed by the body is reduced [9].

Neither drug is significantly broken down by the body (metabolized), so both are released through urine [64].

Pregabalin is considered more effective than gabapentin in treating partial epilepsy and neuropathic pain (postherpetic neuralgia and peripheral neuropathy) [64, 65].

Gabapentin has a similar risk for side effects, drug abuse and withdrawal as pregabalin [9].

Can Dogs Take Gabapentin?

Gabapentin is used in both dogs and cats to treat chronic pain, particularly neuropathic. However, the current evidence for its use in dogs is insufficient.

Several studies found that gabapentin was not better than placebo in relieving pain after surgical procedures in dogs. However, none of these studies used the previously suggested dosing (10 – 20 mg/kg every 8 hours) [66].

Gabapentin effectively reduced postoperative pain in dogs only in combination with morphine, reducing the amount of morphine required [67].

Gabapentin was effective in treating epilepsy in dogs, which was not responsive to other treatments, with few minor side effects [68].

Genetics

Proper kidney function is critical for removing gabapentin from the body. OCTN1 is responsible for transporting gabapentin in the intestine and kidney. The OCTN1-L503F polymorphism decreases the transport of gabapentin in the kidney [69].

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About the Author

Puya Yazdi

Puya Yazdi

MD
Dr. Puya Yazdi is a physician-scientist with 14+ years of experience in clinical medicine, life sciences, biotechnology, and nutraceuticals.
As a physician-scientist with expertise in genomics, biotechnology, and nutraceuticals, he has made it his mission to bring precision medicine to the bedside and help transform healthcare in the 21st century.He received his undergraduate education at the University of California at Irvine, a Medical Doctorate from the University of Southern California, and was a Resident Physician at Stanford University. He then proceeded to serve as a Clinical Fellow of The California Institute of Regenerative Medicine at The University of California at Irvine, where he conducted research of stem cells, epigenetics, and genomics. He was also a Medical Director for Cyvex Nutrition before serving as president of Systomic Health, a biotechnology consulting agency, where he served as an expert on genomics and other high-throughput technologies. His previous clients include Allergan, Caladrius Biosciences, and Omega Protein. He has a history of peer-reviewed publications, intellectual property discoveries (patents, etc.), clinical trial design, and a thorough knowledge of the regulatory landscape in biotechnology.He is leading our entire scientific and medical team in order to ensure accuracy and scientific validity of our content and products.

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