Common, Major and Minor side effects of Gabapentin

Well, talking about the side effects of Gabapentin, in this article we are going to discuss about the common, major and minor side effects.

Let us start with the common side effects first

Common side effects

  • drowsiness
  • sedation
  • dizziness
  • fatigue
  • fever
  • nystagmus
  • ataxia
  • viral infection
  • tremor
  • blurred vision
  • xersotomia
  • irritability
  • peripheral edema
  • diplopia
  • amblyopia

Some Major side effects that need immediate medical attention are

More Common

  • unsteadiness or clumsiness
  • uncontrolled, rolling, continous eye movements

More common effects in children

  • crying
  • anxiety
  • depression
  • behavioural problems like aggressiveness etc
  • constant change in moods
  • increase or hyperactivity in body movements
  • restlessness
  • distrust or suspiciousness
  • overacting, reacting too emotional or too quickly
  • concentration problems or in change in performance at school

Less Common

  • chills
  • cough
  • chest pain
  • memory loss
  • fever
  • irritability, depression or other changes in moods
  • swelling or pain in legs or arms
  • unusual weakness or tiredness
  • difficult or painful urination
  • swollen glands
  • breathlessness
  • unusual bruising or bleeding
  • sore throat
  • tarry, black stools
  • ulcers, sores or white spots in the mouth or lips

Occurrence not known

  • coma
  • dark urine
  • confusion
  • diarrhoea
  • headache
  • increased thirst
  • convulsions
  • joint pain
  • dizziness
  • appetite loss
  • muscle pain or ache
  • nausea
  • irritated or red eyes
  • yellow skin or eyes
  • irregular or fast heartbeat
  • decreased volume of urine
  • hive like or large swelling on eyelids, throat, tongue, feet, sex organs, hands, lips or face

Minor Side effects

Some minor side effects of Gabapentin do not need medical attention. As the body adjusts to the medication the side effects vanish with time.  Your doctor can advise you on how to reduce or prevent such side effects. If the minor side effects turn bothersome or continue to last for a longer period, consult your doctor immediately

More common

  • dementia
  • delusions
  • blurred vision
  • flu or cold like symptoms
  • shaking or trembling
  • hoarseness
  • side or lower back pain
  • swelling of feet, lower legs and hands
  • loss or lack or strength

Less Common side effects

  • body pain or aches
  • full or bloated feeling
  • vision problems
  • congestion
  • constipation
  • earache
  • excessive tearing
  • eye discharge
  • impaired vision
  • increased hunger
  • in coordination
  • frequent urination
  • indigestion
  • ringing ears
  • increased sensitivity to touch and pain
  • sneezing
  • runny nose
  • chest tightness
  • trouble sleeping
  • passing gas
  • trouble thinking
  • twitching
  • weight gain
  • vomiting
  • loss of strength or weakness
  • unexpected weight loss
  • tingling in feet and hands
  • dry or flushed skin
  • excess gas or air in intestines or stomach
  • decreased sexual ability of desire
  • Itching, burning or dry eyes.

Gabapentin Side Effects Weight Gain

Gabapentin 800 mg Tab-IVAGabapentin is frequently used off-label due to the fact that it is considered to have a low potential for abuse and is regarded as non-addictive.  Due to the fact that the drug elicits both analgesic and anticonvulsant effects, it is sometimes preferred by those undergoing various types of surgery.  It reduces preoperative anxiety via its mechanism acting on GABA ergic neurotransmission, and provides postoperative pain relief.

Gabapentin is an effective treatment for neuropathic pain, seizures, and various off-label conditions – many people experience unwanted side effects.  One unwanted side effect that has been reported in a small percentage of users is weight gain.

It is estimated that approximately 3% of all users will experience some form of weight gain.  Most people won’t notice any significant fluctuations in body weight throughout their treatment.  For this reason, Gabapentin is often referred to as a “weight neutral” drug.

there are some studies highlighting the fact that weight gain can occur on Gabapentin, especially when taken at high doses.  In one study of 28 patients taking 3000 mg per day of Gabapentin, 10 patients gained approximately 10% of their bodyweight.  Despite this finding, the majority of patients remained weight neutral, and some even lost weight (3 patients).

The most common side-effects of Gabapentin  listed are these:

Back pain; changes in vision (double or blurred vision); clumsiness; constipation; diarrhea; dizziness; drowsiness; dry mouth; nausea; stomach upset; tiredness; vomiting; weight gain.


Incidentally, these side-effect listings must, by law, include all effects noted by anyone during any of the trials on the way to becoming a drug. That’s why we see strange listings like the one above, where constipation and diarrhea are listed, side by side!

I don’t know the mechanism of the gain, but suspect it’s mostly water retention, since the weight usually fluctuates a lot. An interesting fact about Neurontin is that it is not metabolized by the body at all – nearly all of the unchanged drug is excreted in urine. This is good news for folks taking a lot of it, since if a drug isn’t metabolized, it won’t cause liver or kidney damage.

Drug action and drug metabolism are unrelated, unless metabolism converts a molecule to an active drug in the body (making that molecule a “prodrug”

The body’s job is to get rid of anything that’s not normally there – especially small molecules like drugs. Metabolism is designed to make things easier to excrete, but Neurontin is already easily excreted due to its structure, so the body need do nothing to assure its excretion.

Digestive Side Effects

It is unclear why a small percentage of people lose weight when taking Neurontin, but it may be related to the small percentage who experience unpleasant digestive effects. In the studies highlighted at DailyMed, up to 5.7 percent of adult and adolescent participants experienced diarrhea, up to 3.9 percent nausea, up to 3.3 percent vomiting and up to 2.2 percent heartburn. In children ages 3 to 12, 8.4 percent experienced nausea, some with vomiting.

Gabapentin side effects

The most common side effects of gabapentin in adult patients include dizziness, fatigue, drowsiness, weight gain, and peripheral edema (swelling of extremities). Gabapentin may also produce sexual dysfunction in some patients, symptoms of which may include loss of libido, inability to reach orgasm, and erectile dysfunction.

In children three to twelve years of age, researchers observed susceptibility to mild-to-moderate mood swings, hostility, concentration problems, and hyperactivity. Though rare, the literature reports several cases of hepatotoxicity. Gabapentin should be used carefully in patients with renal impairment due to possible accumulation and toxicity.

An increase in formation of adenocarcinomas was observed in rats during preclinical trials; however, the clinical significance of these results remains undetermined. Gabapentin is also known to induce pancreatic acinar cell carcinomas in rats through an unknown mechanism, perhaps by stimulation of DNA synthesis; these tumors did not affect the lifespan of the rats and did not metastasize.

Get emergency medical help if you have any of these signs of an allergic reaction to gabapentin: hives; fever; swollen glands; painful sores in or around your eyes or mouth; difficulty breathing; swelling of your face, lips, tongue, or throat.

Report any new or worsening symptoms to your doctor, such as: mood or behavior changes, anxiety, depression, or if you feel agitated, hostile, restless, hyperactive (mentally or physically), or have thoughts about suicide or hurting yourself.

Call your doctor at once if you have:

  • increased seizures;
  • fever, swollen glands, body aches, flu symptoms;
  • skin rash, easy bruising or bleeding, severe tingling, numbness, pain, muscle weakness;
  • upper stomach pain, loss of appetite, dark urine, jaundice (yellowing of the skin or eyes);
  • chest pain, irregular heart rhythm, feeling short of breath;
  • confusion, nausea and vomiting, swelling, rapid weight gain, urinating less than usual or not at all;
  • new or worsening cough, fever, trouble breathing;
  • rapid back and forth movement of your eyes; or
  • severe skin reaction — fever, sore throat, swelling in your face or tongue, burning in your eyes, skin pain, followed by a red or purple skin rash that spreads (especially in the face or upper body) and causes blistering and peeling.

Some side effects are more likely in children taking gabapentin. Contact your doctor if the child taking this medication has any of the following side effects:

  • changes in behavior;
  • memory problems;
  • trouble concentrating; or
  • acting restless, hostile, or aggressive.

Common gabapentin side effects may include:

  • dizziness, drowsiness;
  • dry mouth, blurred vision;
  • headache;
  • diarrhea; or
  • swelling in your hands or feet.

Some side effects may be serious. If you experience any of the following symptoms, call your doctor immediately:

  • rash
  • itching
  • swelling of the face, throat, tongue, lips, or eyes
  • hoarseness
  • difficulty swallowing or breathing
  • seizures

Get medical help right away if you have any serious side effects, including: unusual fever, swollen glands, yellowing skin/eyes, unusual tiredness, dark urine, change in the amount of urine, chest pain.

Gabapentin Side Effects

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.