Surprising Gabapentin Side Effects

Gabapenin is one of the most commonly prescribed drugs by doctors. At last count over 50 million prescriptions were dispensed annually. It is used for an amazing array of off-label indications. That means physicians are giving it to patients for conditions that the Food and Drug Administration has never approved and for which there may be modest scientific support at best. The reader who asked the question below provides a classic example of just such prescribing. We would not get concerned if this drug was perfectly safe. But gabapentin side effects are not trivial as you will discover in our answer below.

Q. I would like to know your feelings on the regular use of gabapentin for chronic insomnia. As a long time suffer of insomnia, my doctor has prescribed a myriad of drugs. Most recently upwards of 3600 mg of gabapentin at bedtime.

After more than 6 months of use I have noticed that gabapentin is taking a toll on my quality of life. Your thoughts please!

A. Gabapentin (Neurontin) was originally developed as an anti-seizure drug. It was approved by the FDA as an “add-on” treatment for patients with epilepsy in 1993. Although researchers do not completely understand how gabapentin works to control seizures, they think it affects production of a neurochemical in the brain called GABA (gamma-aminobutyric acid).

The Off-Label Marketing Boondoggle:

Pfizer, the manufacturer of the brand name Neurontin, got into major trouble when it marketed this drug for off-label uses. A company has historically not been allowed to promote a medicine for things that the FDA has not approved. In Pfizer’s case, these unofficial uses for Neurontin included bipolar disorder, alcohol withdrawal, migraines and pain. The company eventually paid $430 million in penalties and admitted to fraudulent promotion.

We mention this because Neurontin is currently available generically as gabapentin. In addition to treating epilepsy, the drug now has official FDA approval for alleviating nerve pain caused by shingles (postherpetic neuralgia).

Off-Label Prescribing Continues:

Even though gabapentin does not have the FDA’s blessing for treating other kinds of nerve pain (neuropathy), many doctors are using it for this purpose. Some physicians prescribe it to patients with fibromyalgia and migraines as well as to control hot flashes brought on by menopause, even though there is no official blessing from the FDA. This is not illegal. Doctors can prescribe any drug for any reason they see fit. That said, we could find little evidence to suggest that gabapentin would be helpful for insomnia. This is definitely an “off-label” use if ever there was one.

If there were few, if any, side effects associated with gabapentin we would not worry too much about the prescribing of this drug for so many off-label uses. But gabapentin has some potentially worrisome adverse effects. The FDA has issued this warning:

“Antiepileptic drugs (AEDs), including Neurontin [gabapentin], increase the risk of suicidal thoughts or behavior in patients taking these drugs for any indication. Patients treated with any AED for any indication should be monitored for the emergence or worsening of depression, suicidal thoughts or behavior, and/or any unusual changes in mood or behavior.”

The FDA also mentions an “unexpectedly high incidence of pancreatic acinar adenocarcinomas” [cancer] in male rats that received gabapentin. The agency adds the unhelpful caveat that the, “clinical significance of this finding is unknown.” In other words, no one knows whether this animal research means that men will be at higher risk for pancreatic cancer. This is not the sort of thing that the FDA requires drug companies to follow up on because the long-term research needed to detect a cancer signal can be quite challenging and expensive.

Gabapentin Side Effects:

• Dizziness, vertigo
• Fatigue and or tiredness
• Unsteadiness or incoordination
• Abnormal thinking, anxiety, hostility, confusion, amnesia,
• Depression, suicidal thoughts, mood changes
• Fluid accumulation in feet, edema of face or extremities
• Digestive distress, indigestion, loss of appetite, gas, nausea, vomiting, diarrhea
• Dry mouth, dental problems, gingivitis
• Blurred vision, double vision, unusual eye movements (nystagmus)
• Headache
• Withdrawal seizures (never stop gabapentin suddenly!)
• Blood disorders
• Skin rash (alert your M.D. immediately if this occurs!)
• Upper respiratory tract infections, fever
• High blood pressure
• Palpitations
• Tremor, jerky movements
• Joint pain, joint stiffness, arthritis

Gabapentin Discontinuation Syndrome (aka Withdrawal):

No one should ever discontinue gabapentin abruptly. Like so many medications that affect the central nervous system, sudden withdrawal may lead to unexpected side effects. Some that have been reported include anxiety, insomnia, nausea, pain, sweating and even seizures. Sadly, though, the FDA gives very little guidance to prescribers about how to gradually taper patients off gabapentin.

Stories from Readers:

When you read a long list of gabapentin side effects, like those listed above, your eyes glaze over almost instantly. Drug companies have recognized this, which is why there is so much prescription drug advertising on TV and in magazines. There was a time when the pharmaceutical industry worried about telling patients about such serious side effects as irregular heart rhythms, hypertension or blood disorders. Not any more. They realize that even warnings about heart attacks, strokes or death do not scare people away.

The only way we can help you understand what such side effects are like in real life is to share stories from visitors to this website. Here are just a handful. You can read hundreds more in the comment section at the bottom of this article.

Sue in Corvallis, Oregon writes about her husband:

“My husband has been on gabapentin for anxiety and depression for over 3 years now. The doctors started him on this to get him off the benzodiazepines he had been on for 20 years.

“While it seemed to help in the beginning, they kept increasing the dose. He is currently on 2700 mg per day (900 mg x 3). That is way too much.

He has changed so much – cries hysterically, has mood swings, goes from insomnia to sleep deprivation. He has tremors, blurred vision and now talks about suicide all the time. He is so discouraged.

“If the FDA has not okayed gabapentin for anxiety and depression why do docs prescribe it? I am ready to complain to the drug company! He and I just want his life back. Lying in bed 85% of the time is not helpful.”

Susan in Milton, Florida shares a tragic story:

“My boyfriend was prescribed gabapentin for his diabetic neuropathy. I can see now that he became more withdrawn and one evening left the house without my knowledge and went to the hospital where they prescribed sertraline (Zoloft) and counseling the following Monday.

“He committed suicide Saturday morning. If I had been told by his doctor about the side effects of gabapentin I could have done something to prevent his death.”

Lynn in Mobile, Alabama warns about weight gain from gabapentin (she isn’t the only one):

“I have been on gabapentin (800 mg 3 x daily) for about 13 years. It was prescribed for spinal problems and pain problems in general. When I first started gabapentin it  worked great. But I experienced a tremendous amount of weight gain, like close to 100 pounds!

“As time has gone on I have noticed my life has changed so much. I have developed random weird thoughts. I never want to go anywhere or do anything except sit in my recliner and watch tv.

“I feel a nervous wreck if it’s been awhile since I have taken my gabapentin. I have an overwhelming feeling sometimes, like a flash in my mind of suicidal thoughts. My mind feels scrambled. It is very hard to explain.

“My pain is so unbearable sometimes that I am afraid to get off gabapentin. I am 44 years old and weighing around 250 pounds! I look horrible and don’t want anyone to see me period.”

Jonanne in England has had trouble getting off gabapentin:

“I had been on gabapentin for about two years for nerve damage from gallbladder surgery. I was on 300 mg 3 times a day. These tabs were a wonder drug and took my pain away almost immediately.

“Now two years later I returned to the doctor and told her I would like to come off this medication as I feel it’s time. For the last few weeks she weaned me off them with a withdrawal chart, which I followed till the last tablet. Just two days after being completely off gabapentin the side effects have hit me: dizziness, headaches, nausea, and I actually fainted, which I have never done before in my life.

“The doctor told me I had come off gabapentin too quickly and to start taking a lower dosage. I started weaning myself off gabapentin  gradually again, but still the same symptoms. I have not taken any pills for 5 days and the dizziness and headaches are back. I am not sleeping. I am also having hot sweats in the night and feeling very low in mood. I am not going back on gabapentin! I am going to persevere even with these symptoms and hope I can cope. I feel like I am going around the bend and will never get better.”

The People’s Pharmacy Bottom line:

Gabapentin is an effective treatment for epilepsy and the excruciating pain that sometimes lingers after an attack of shingles. Although it is quite frequently prescribed for off-label uses, the benefit/risk ratio is not clear. The drug has many potentially serious side effects. We are surprised that your doctor prescribed such a heavy-duty drug for insomnia, especially at such a high dose. The “normal” dose of gabapentin for treating epilepsy or shingles pain would be up to 1800 mg daily. Although 3600 mg is sometimes prescribed, it would have to be considered a high dose, especially for an unapproved use.

Since you report that gabapentin is affecting the quality of your life in a negative way, perhaps it is time to talk to your doctor about reconsidering this drug and discussing a VERY gradual withdrawal process. You may need to consult a sleep specialist to help you deal with your chronic insomnia in a more integrative manner.

You may find our recently revised Guide to Getting A Good Night’s Sleep worth consulting.

People with nerve pain may find our one-hour interview with David Casserett, MD, quite fascinating. In it he talks about medical marijuana for “neuropathic” pain. It is titled, “How One Doctor Changed His Mind About Medical Marijuana.”

Show 1027: How One Doctor Changed His Mind about Medical Marijuana (Archive)

If you are worried about the psychoactive properties of marijuana, you may find this article about canabidiol (CBD) oil of substantial interest. It may ease nerve pain without causing people to get “high.”

This article was revised: 12/8/2016