Gabapentin: 7 things you should know - Drugs.com (2024)

Medically reviewed by Carmen Pope, BPharm. Last updated on June 18, 2024.

1. How it works

• Gabapentin is an anticonvulsant with pain-relieving effects that may be used to treat partial-onset seizures or relieve nerve pain.
• Research has shown gabapentin binds strongly to a specific site (called the alpha2-delta site) on voltage-gated calcium channels and this is thought to be the way gabapentin works to relieve nerve pain and lower the risk of seizures.
• Gabapentin enacarbil (brand name Horizant) is a prodrug of gabapentin that has been designed to overcome the limitations of gabapentin, such as poor absorption and a short duration of action. It requires hydrolyzation in the gastrointestinal tract to become active.
• Gabapentin belongs to the group of medicines known as anticonvulsants.

2. Upsides

• May be used in addition to other medication to reduce seizure frequency in adults and children aged three and older with partial-onset seizures.
• May be used in the management of postherpetic neuralgia (persistent nerve pain following Shingles infection) in adults.
• Gabapentin enacarbil (brand name Horizant) may be used to relieve restless legs syndrome (RLS) or nerve pain associated with postherpetic neuralgia. Horizant is a long-acting prodrug of gabapentin that only requires once-daily dosing. It is usually taken once daily around 5 pm.
• Gabapentin is available as a generic; however, not all generics are interchangeable with some branded versions of gabapentin.
• Gabapentin may be used off-label (this means for an indication that has not been approved by the FDA but may still have a place in therapy) for some other indications such as fibromyalgia, persistent hiccups, migraine prevention, and hot flashes.Different brand names and formulations of gabapentin are available, each with specific uses and dosing instructions.
• Neurontin: Treats pain from shingles (postherpetic neuralgia) and, when combined with other seizure medications, treats partial-onset seizures in adults and children over 3 years old.
• Gralise: Specifically for postherpetic neuralgia (pain after shingles) and should not be used for any other conditions.
• Horizant: An extended-release tablet for restless legs syndrome and postherpetic neuralgia.
• Generic gabapentin capsules: Postherpetic neuralgia and as an additional therapy for partial-onset seizures in adults and children over 3 years old.

3. Downsides

If you are between the ages of 18 and 60, take no other medication or have no other medical conditions, side effects you are more likely to experience include:

• Dizziness, drowsiness, tiredness, fever, and nystagmus (a rapid and uncontrollable movement of the eyes). Drowsiness caused by gabapentin may affect your ability to drive or operate machinery. Alcohol and other drugs with sedative properties enhance this effect.
• May cause behavioral problems, hostility or aggression, or thought disturbances when used to treat epilepsy in children aged three to twelve years.
• Other side effects may include blurred vision, amblyopia (lazy eye), dry mouth, peripheral edema (fluid retention in the feet and hands), tremor, sexual dysfunction, and gastrointestinal disturbances.
• Best titrated up slowly to reduce the risk of side effects; however, this may delay the onset of an effect.
• Similar to other anticonvulsant medicines, gabapentin may increase the risk of depression and suicidal thoughts, particularly in young adults under the age of 24.
• Gabapentin has been associated with a discontinuation syndrome when abruptly stopped. Symptoms include anxiety, insomnia, nausea, pain, and sweating. It should be tapered off slowly under a doctor's advice.
• The dosage of gabapentin needs to be reduced for kidney disease.
• Rarely do hypersensitivity reactions occur. Symptoms may include fever, rash, swollen lymph nodes, swollen facial features, or throat swelling.
• May interact with some other medications including antacids, hydrocodone, morphine, and other drugs that cause sedation or dizziness. May also cause false-positive results on some urinary protein tests.
• There have been some reports of gabapentin misuse and abuse, particularly in people with a history of drug abuse. Be alert for this possibility.
• Gabapentin requires three times daily administration because of its short duration of effect. Gabapentin enacarbil (brand name Horizant) only requires once-daily dosing.
• Only effective for partial-onset seizures, not other types of seizure disorders.
• Some branded and generic forms of gabapentin are not interchangeable.

Note: In general, seniors or children, people with certain medical conditions (such as liver or kidney problems, heart disease, diabetes, seizures) or people who take other medications are more at risk of developing a wider range of side effects. View complete list of side effects

4. Bottom Line

• Gabapentin is an anticonvulsant with pain-relieving effects that may be used to treat certain seizure disorders or relieve nerve pain. Common side effects include dizziness or drowsiness and it may cause a withdrawal syndrome on discontinuation so should not be stopped abruptly.

5. Tips

• Different brand names and formulations of gabapentin are available, each with specific uses and dosing instructions. Each time you collect your prescription, make sure you have the correct brand or dose.
• You can take Neurontin with or without food, whichever works best for you, it is usually taken three times daily. Try to space your doses evenly throughout the day, and no more than 12 hours apart. If your doctor prescribes 600 mg or 800 mg tablets and you need to break one in half for dosing, be sure to take the other half at your next scheduled dose or within 28 days of breaking it. Don't store a broken tablet for extended periods.
• Gralise is for once-daily use, taken with food in the evening. Swallow the tablets whole; don't break, crush, or chew them. Gralise has different dosing requirements than other gabapentin medications and cannot be substituted.
• Horizant is specifically for restless legs syndrome and is usually taken around 5 PM. Swallow the tablets whole with food. Don't break, crush, or chew them. Don't switch Horizant with other Gabapentin medications.
• If your doctor prescribes a liquid form, use the measuring cup provided by your manufacturer or pharmacist for accurate dosing. Don't use kitchen teaspoons or measuring cups.
• Gabapentin can cause drowsiness or dizziness. Avoid driving, operating machinery, or activities requiring alertness until you know how it affects you. It can also increase your risk of falling. Take steps to prevent falls at home, like removing loose rugs. Get immediate medical help if you experience a rash, fever, trouble breathing, or facial swelling while taking gabapentin.
• Don't abruptly stop taking gabapentin because you may experience withdrawal symptoms such as anxiety, agitation, confusion, insomnia, nausea, pain, and sweating which may be severe. It should be tapered off slowly under a doctor's advice. Talk to your doctor about the best way to taper off gabapentin.
• Watch for changes in mood, worsening depression, or suicidal thoughts. Report any concerns to your doctor.
• Don't take gabapentin with antacids like Maalox or Gaviscon. Take them at least two hours apart.
• Always follow your doctor's instructions for taking gabapentin. Don't adjust the dose without their advice.

6. Response and effectiveness

• Peak concentrations of gabapentin (immediate-release) occur within 2 to 3 hours. Although gabapentin may improve sleep problems due to nerve pain within a week, it may take up to two weeks for symptom relief from nerve pain to occur. A reduction in seizure frequency is usually apparent within a few weeks.
• Gabapentin enacarbil (brand name Horizant), a prodrug of gabapentin, is rapidly absorbed by nutrient transporters along the gastrointestinal tract and then quickly hydrolyzed to gabapentin. This means gabapentin enacarbil only needs to be given once a day. However, symptom relief from RLS or postherpetic neuralgia may take several days or weeks to develop.
• Immediate-release gabapentin capsules require three times daily dosing (except in kidney disease).

7. Interactions

Medicines that interact with gabapentin may either decrease its effect, affect how long it works, increase side effects, or have less of an effect when taken with gabapentin. An interaction between two medications does not always mean that you must stop taking one of the medications; however, sometimes it does. Speak to your doctor about how drug interactions should be managed.

Common medications that may interact with gabapentin include:

• antacids, such as those containing aluminum and magnesium
• anti-anxiety medications, such as diazepam, lorazepam, and flunitrazepam
• antidepressants, such as amitriptyline, citalopram, fluoxetine, paroxetine
• antihistamines, such as chlorpheniramine, promethazine
• antipsychotics, such as aripiprazole, chlorpromazine, haloperidol
• buprenorphine
• narcotic pain relievers, such as oxycodone and morphine
• propoxyphene
• sedatives or sleeping pills
• tramadol.

Alcohol may worsen the side effects of gabapentin such as drowsiness and dizziness.

Note that this list is not all-inclusive and includes only common medications that may interact with gabapentin. You should refer to the prescribing information for gabapentin for a complete list of interactions.

References

• Gabapentin. Revised 06/2024. Major Pharmaceuticals, LLC. https://www.drugs.com/pro/gabapentin.html
• Horizant (gabapentin enacarbil) [Package Insert]. Revised 08/2022. Azurity Pharmaceuticals, Inc. https://horizant.com/Horizant-Prescribing-Information.pdf
• Gralise (gabapentin). Revised 04/2023. Almatica Pharma LLC. https://www.gralise.com/static/documents/gralise-prescribing-information.pdf?rev=2
• Neurontin (gabapentin). Revised 10/2017. Parke-Davis https://www.accessdata.fda.gov/drugsatfda_docs/label/2017/020235s064_020882s047_021129s046lbl.pdf

Further information

Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use gabapentin only for the indication prescribed.

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circ*mstances.

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