As with any medicine,  side effects are possible with gabapentin (Neurontin®); however, not everyone who takes the  medication will experience side effects. In fact, most people tolerate it quite well. If side effects do occur, in most cases, they are minor and either require no treatment or are easily treated by you or your healthcare provider. 

Common Gabapentin Side Effects 

Gabapentin has been studied thoroughly in clinical trials. In these studies, the  side effects that occur in a group of people taking the drug  are documented and compared to side effects that occur in another group of people  not taking the drug. This way, it is possible to see what side effects occur, how often they appear, and how they compare to the group not taking the medicine.
  
In these studies, the most common side effects of gabapentin included: 

• Dizziness -- in up to 28 percent of people 
• Drowsiness -- up to 21.4 percent 
• Coordination problems -- up to 12.5 percent 
• Infections -- up to 10.9 percent 
• Fever -- up to 10.1 percent 
• Nausea  or vomiting -- up to 8.4 percent 
• Swelling or fluid retention in the legs, feet, arms, or hands -- up to 8.3 percent 
• Unusual eye movements -- up to 8.3 percent. 

Other common gabapentin side effects, occurring in 1 to 7 percent  of people, included: 

• Shakiness (tremor) 
• Double vision  or blurred vision
• Weakness or fatigue 
• Diarrhea or constipation 
• Dry mouth (see Neurontin and Dry Mouth) 
• Increased appetite  or weight gain (see Neurontin and Weight Gain) 
• Bronchitis  
• Accidental injury 
• Sore throat 
• Hyperactivity (in children) 
• Changes in thinking (such as difficulty concentrating) 
• Nervousness  
• Speech problems 
• Memory loss (amnesia) 
• Indigestion  or heartburn 
• Gas
• Back pain
• Problems walking 
• Twitching
• High blood sugar (hyperglycemia) 
• Conjunctivitis ("pink eye") 
• Ear infection 
• Flushing  or hot flashes. 

Serious Gabapentin Side Effects 

• Some side effects of gabapentin, while occurring infrequently, are potentially serious and should be reported immediately to  your healthcare provider. These include, but are not limited to: 
• Depression
• Hostility
• Severe dizziness, confusion, or coordination problems that do not improve with time 

Signs of an allergic reaction, including: 

• Unexplained rash 
• Hives  
• Itching  
• Unexplained  swelling

Suicidal thinking or behavior (see Seizure Medications and Suicide).
  
Rare Gabapentin Side Effects 

Rare side effects  of gabapentin occurred in less than 1 percent of people taking  the drug. Because these side effects are so uncommon, it can be difficult to tell whether they are actually caused by gabapentin  or by factors unrelated to the medication.
  
Some of these less common side effects include, but are not limited to: 

• Weight loss 
• "Hangover" effect 
• Migraines  
• High cholesterol 
• Hemorrhoids  
• Ulcers  
• Hiatal hernia 
• Irritable bowel syndrome (IBS) 
• Thyroid problems (including hyperthyroidism  or hypothyroidism)
• Arthritis
• Sexual problems (see Neurontin Sexual Side Effects) 
• Snoring  
• Sensitivity to the sun 
• Psoriasis  
• Kidney stones. 

Final Thoughts on  Gabapentin Side Effects 

You  may experience some or none of the gabapentin  side effects listed in this article. Unfortunately, there is no way for  your healthcare provider to know beforehand  if you will have side effects from a medicine that you have never tried. Therefore, make sure to let your healthcare provider know if you develop  any side effects while taking the drug. Also, let your healthcare provider know if  you develop something that "just does not seem right." While it may not be  a side effect of gabapentin, your healthcare provider will be able to diagnose and treat  the problem. 

Notes: Dr. Nelson Crumfield

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EditText of this page (last edited June 12, 2010)