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What is Gabapentin Side Effects ?

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Gabapentin capsules, tablets, and oral solution are used along with other medications to help control certain types of seizures in people who have epilepsy. Gabapentin capsules, tablets, and oral solution are also used to relieve the pain of postherpetic neuralgia (PHN; the burning, stabbing pain or aches that may last for months or years after an attack of shingles).

⚠️ Side Effects of Gabapentin

Gabapentin is an anticonvulsant and nerve pain medication commonly prescribed for:

  • Seizure disorders (as adjunct therapy)
  • Postherpetic neuralgia
  • Peripheral neuropathy
  • Fibromyalgia (off-label)
  • Generalized anxiety disorder (off-label)

While generally well tolerated, gabapentin can cause side effects that range from mild to severe.

🩺 Common Side Effects

These are usually mild and tend to improve over time:

Side Effect Explanation
Drowsiness / Fatigue CNS depressant effect
Dizziness / Lightheadedness Especially during dose titration
Swelling (edema) Particularly in hands, feet, or lower legs
Weight gain Possibly due to increased appetite or fluid retention
Tremor Mild shakiness in hands or arms
Blurred or double vision CNS effect on coordination
Difficulty concentrating Cognitive dulling or “brain fog”
Dry mouth Common with CNS agents
Nausea Typically transient during early use

🚨 Serious Side Effects

Seek immediate medical attention if any of these occur:

Serious Side Effect Concern
Suicidal thoughts or behavior Increased risk with many antiepileptic drugs
Severe allergic reactions (rash, swelling, breathing difficulty) Rare but serious (e.g., DRESS syndrome)
Mood changes (depression, anxiety, aggression) Especially in younger patients
Respiratory depression (shallow breathing) Risk increases when combined with opioids
Loss of coordination or falls More common in elderly patients
Vision changes or eye pain May indicate optic issues or toxicity
Seizure worsening (in epileptic patients) Paradoxical effect in some cases

⚠️ Withdrawal Symptoms

Gabapentin should be tapered off gradually under medical supervision to avoid withdrawal effects:

Withdrawal Symptoms
Anxiety
Insomnia
Sweating
Nausea
Pain flare-up
Seizures (in seizure patients)

👩‍⚕️ Special Precautions

  • Elderly: Increased risk of sedation, falls, and cognitive impairment.
  • Renal Impairment: Dosage adjustment is required.
  • Combining with CNS depressants (e.g., opioids, alcohol, benzodiazepines) increases the risk of serious side effects like respiratory depression.

Gabapentin Side Effects

Gabapentin extended-release tablets (Horizant) are used to treat restless legs syndrome (RLS; a condition that causes discomfort in the legs and a strong urge to move the legs, especially at night and when sitting or lying down). Gabapentin is in a class of medications called anticonvulsants. Gabapentin treats seizures by decreasing abnormal excitement in the brain. Gabapentin relieves the pain of PHN by changing the way the body senses pain. It is not known exactly how gabapentin works to treat restless legs syndrome.

Gabapentin Side Effects

Gabapentin Side Effects
Gabapentin Side Effects

Along with its needed effects, a medicine may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor immediately if any of the following side effects occur:

More common

      1. Clumsiness or unsteadiness
      2. continuous, uncontrolled, back-and-forth, or rolling eye movements

More common in children

      1. Aggressive behavior or other behavior problems
      2. anxiety
      3. concentration problems and change in school performance
      4. crying
      5. depression
      6. false sense of well-being
      7. hyperactivity or increase in body movements
      8. rapidly changing moods
      9. reacting too quickly, too emotional, or overreacting
      10. restlessness
      11. suspiciousness or distrust

Less common

      1. Black, tarry stools
      2. chest pain
      3. chills
      4. cough
      5. depression, irritability, or other mood or mental changes
      6. fever
      7. loss of memory
      8. pain or swelling in the arms or legs
      9. painful or difficult urination
      10. sore throat
      11. sores, ulcers, or white spots on the lips or in the mouth
      12. swollen glands
      13. unusual bleeding or bruising
      14. unusual tiredness or weakness

Incidence not known

      1. Abdominal or stomach pain
      2. blistering, peeling, or loosening of the skin
      3. clay-colored stools
      4. coma
      5. confusion
      6. convulsions
      7. dark urine
      8. decreased urine output
      9. diarrhea
      10. difficult or troubled breathing
      11. dizziness
      12. fast or irregular heartbeat
      13. headache
      14. increased thirst
      15. irregular, fast or slow, or shallow breathing
      16. itching or skin rash
      17. joint pain
      18. large, hive-like swelling on the face, eyelids, lips, tongue, throat, hands, legs, feet, or sex organs
      19. loss of appetite
      20. muscle ache or pain
      21. nausea
      22. pale or blue lips, fingernails, or skin
      23. red skin lesions, often with a purple center
      24. red, irritated eyes
      25. unpleasant breath odor
      26. vomiting of blood
      27. yellow eyes or skin

Some side effects may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects. Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

More common

      1. Blurred vision
      2. cold or flu-like symptoms
      3. delusions
      4. dementia
      5. hoarseness
      6. lack or loss of strength
      7. lower back or side pain
      8. swelling of the hands, feet, or lower legs
      9. trembling or shaking

Less common or rare

      1. Accidental injury
      2. appetite increased
      3. back pain
      4. bloated or full feeling
      5. body aches or pain
      6. burning, dry, or itching eyes
      7. change in vision
      8. change in walking and balance
      9. clumsiness or unsteadiness
      10. congestion
      11. constipation
      12. cough producing mucus
      13. decrease in sexual desire or ability
      14. dryness of the mouth or throat
      15. earache
      16. excess air or gas in the stomach or intestines
      17. excessive tearing
      18. eye discharge
      19. feeling faint, dizzy, or lightheadedness
      20. feeling of warmth or heat
      21. flushed, dry skin
      22. flushing or redness of the skin, especially on the face and neck
      23. frequent urination
      24. fruit-like breath odor
      25. impaired vision
      26. incoordination
      27. increased hunger
      28. increased sensitivity to pain
      29. increased sensitivity to touch
      30. increased thirst
      31. indigestion
      32. noise in the ears
      33. pain, redness, rash, swelling, or bleeding where the skin is rubbed off
      34. passing gas
      35. redness or swelling in the ear
      36. redness, pain, swelling of the eye, eyelid, or inner lining of the eyelid
      37. runny nose
      38. sneezing
      39. sweating
      40. tender, swollen glands in the neck
      41. tightness in the chest
      42. tingling in the hands and feet
      43. trouble sleeping
      44. trouble swallowing
      45. trouble thinking
      46. twitching
      47. unexplained weight loss
      48. voice changes
      49. vomiting
      50. weakness or loss of strength
      51. weight gain

Other side effects not listed may also occur in some patients. If you notice any other effects, check with your healthcare professional.

Call your doctor for medical advice about side effects. You may report side effects to the FDA at 1-800-FDA-1088.